WO2008041469A1

WO2008041469A1 - Imaging device

Info

Publication number: WO2008041469A1
Application number: PCT/JP2007/067921
Authority: WO
Inventors: Hiroshi Nishizawa
Original assignee: Panasonic Corporation
Priority date: 2006-10-03
Filing date: 2007-09-14
Publication date: 2008-04-10

Abstract

An imaging device having an optical system for collecting light from an object, a semiconductor imaging element (4) for receiving the light collected by the optical system and creating an imaging signal, and a transparent member (5) provided between the optical system and the semiconductor imaging element (4) and having a refraction index continuously varying according to an applied electric field. When an electric field is applied to the transparent member (5), its refraction index varies continuously to continuously change the length of the light path. This realizes auto-focusing without movement of a lens, which is effective to downsize the imaging device and reduces degradation in image quality.

Description

Specification

Imaging device

Related applications

[0001] This application claims 禾 IJ benefits of patent application number 2006-271 441 and patent application number 2006-271443 filed in Japan on October 3, 2006, and the contents of this application are incorporated It is hereby incorporated by reference.

Technical field

The present invention relates to an image pickup apparatus using a semiconductor image pickup device, and more particularly to an image pickup apparatus that switches autofocus or shooting mode.

Background art

Conventionally, an imaging apparatus with an autofocus function has been known, as can be seen in Japanese Unexamined Patent Application Publication Nos. 2005-121950 and 2006-119247.

FIG. 6 is a diagram showing an outline of a conventional imaging apparatus with an autofocus function. Image pickup devices that integrate a lens and an image sensor as shown in Fig. 6 are often used for mobile terminals with cameras. The lens 42 is composed of two aspheric lenses. The lens 42 is held by a resin lens barrel 43. A part of the lens barrel 43 is configured to engage with an actuator 41 using a piezoelectric element. A lens 42 and a semiconductor imaging device 44 are disposed on the optical axis, and an IR filter 45 is inserted therebetween.

Next, the operation of the imaging device shown in FIG. 6 will be described. Light from the subject is collected by the lens 42. The condensed light is incident on the semiconductor imaging device 44 after the infrared light is limited by the IR filter 45. The semiconductor imaging device 44 converts light from the subject into an electric signal, and then performs focusing processing based on the high-frequency component signal by a signal processing circuit (not shown). In this process, the imaging apparatus determines that the in-focus state is achieved when the high frequency component becomes higher than a predetermined threshold value. A method such as mountain climbing is used for the sequence up to this focusing. Focusing is performed while pressing the shutter button (halfway). After the in-focus determination is made, the imaging operation is completed by further depressing the shutter button. At this time, the actuator 41 determines whether the lens is based on an external signal. By moving the entire lens barrel 43 in the optical axis direction with respect to 42, the distance between the lens 42 and the semiconductor imaging device 44 is changed, and the back focus is adjusted to perform the focusing operation.

[0006] Furthermore, for mobile phones with cameras, thin and small imaging devices in which a lens and an imaging element are integrated are often used. As disclosed in Japanese Patent Application Laid-Open No. 2006-99072, these image pickup apparatuses are switched between a normal shooting mode and a macro shooting mode by a lever. For example, the entire lens is moved in the optical axis direction by the rotation of the lever, and the shooting mode is switched by changing the physical distance between the image sensor and the entire lens. ! /

[0007] In addition, Japanese Patent Laid-Open No. 2005-300671 discloses that in a foldable mobile phone with a camera, when taking a QR code, the mobile phone can be opened at a substantially right angle so that macro photography can be performed. It is disclosed that the shooting mode is switched.

[0008] Also, Japanese Patent Application Laid-Open No. 2005-276743 discloses an invention that changes the in-focus distance by operating a focus switching lever arranged on the side of a mobile phone in a mobile phone with a camera. ing.

As described above, in the conventional imaging apparatus, the entire lens is moved in the optical axis direction by a lever or the like, and switching between the normal imaging mode and the macro imaging mode is performed. Disclosure of the invention

Problems to be solved by the invention

[0010] However, in the conventional imaging apparatus, during autofocus, the actuator moves the lens in the optical axis direction. In this case, the lens is moved by the actuator. As a result, there is a problem that the image is shifted in a direction perpendicular to the optical axis direction or the image is inclined with respect to the imaging surface. In addition, since an actuator must be provided, the overall size of the imaging device is larger than that of an equivalent fixed-focus imaging device, which hinders downsizing of the imaging device. Further, since the lens moves, the guide component (guide component) and the lens component slide. This sliding generates wear powder, which causes the captured image to deteriorate.

[0011] In the conventional imaging device, when switching between the normal shooting mode and the macro shooting mode

By rotating the lever, etc., the entire lens moves in the optical axis direction. The entire lens moves to the subject side during macro photography. As a result, the size of the entire imaging device in the optical axis direction becomes larger during macro shooting, so the imaging device with macro switching is downsized compared to a fixed-focus imaging device that does not have the same macro switching function. Was inhibited.

[0012] In addition, in the conventional imaging device, the size of the imaging device is the maximum length during macro shooting. Therefore, when the imaging device is mounted on a portable terminal device such as a mobile phone, the imaging device The space that can store the maximum length must be secured! /, So the movement of the lens hindered the thinning of the mobile terminal device.

[0013] In addition, with the switching to the macro shooting mode, the entire lens moves by rotating a lever or the like. At this time, the parts slide between the lever and the contact portion of the lens (lens barrel) or between the lens barrel and the guide portion. This sliding may cause wear powder and dust adhering to the parts to move or scatter, and there is a problem that these wear powder causes deterioration of the captured image.

[0014] The present invention has been made to solve the above-mentioned problems, and the object thereof is to realize autofocus without moving the lens, thereby being effective for downsizing of the imaging device. An object of the present invention is to realize an imaging apparatus with little image degradation.

[0015] In addition, an object of the present invention is to realize switching of the shooting mode without moving the lens when changing the shooting mode, thereby realizing a reduction in the size of the imaging device or a reduction in the thickness of the portable terminal device. Rukodomi.

[0016] Further, an object of the present invention is to realize an imaging apparatus that can prevent generation of wear powder due to sliding and eliminate image degradation by eliminating a mechanical sliding portion that moves a lens. .

[0017] Furthermore, an object of the present invention is to constitute a mobile terminal device such as a camera-equipped mobile phone using this imaging device, thereby reducing the size and thickness of the mobile terminal device and reducing image degradation. This is to realize a small number of portable terminal devices with cameras.

Means for solving the problem

[0018] The imaging apparatus of the present invention includes an optical system that collects light from a subject, an imaging element that receives the light collected by the optical system and generates an imaging signal, the optical system, and the imaging Between the elements And a transparent member whose refractive index changes according to the applied electric field.

[0019] As described below, there are other aspects of the present invention. Accordingly, the disclosure of the present invention is intended to provide part of the present invention and is not intended to limit the scope of the invention described and claimed herein.

Brief Description of Drawings

FIG. 1 is a perspective view showing an imaging apparatus according to a first embodiment of the present invention.

[Fig. 2] Fig. 2 is a cross-sectional view showing an imaging apparatus which exerts a force on the first embodiment of the present invention.

[Fig. 3] Fig. 3 is a cross-sectional view showing a transparent member which exerts a force on the first embodiment of the present invention.

[FIG. 4] FIG. 4 is a graph showing the electric field and refractive index characteristics of the transparent member according to the first embodiment of the present invention.

FIG. 5 is a plan view showing a mobile terminal device according to a second embodiment of the present invention.

[FIG. 6] FIG. 6 is a diagram showing an outline of a conventional imaging apparatus with an autofocus function.

BEST MODE FOR CARRYING OUT THE INVENTION

[0021] Hereinafter, a detailed description of the present invention will be described. It will be understood that the embodiments described below are merely examples of the present invention, and the present invention can be modified in various ways. Accordingly, the specific configurations and functions disclosed below do not limit the scope of the claims.

[0022] The imaging apparatus of the present embodiment includes an optical system that collects light from a subject, an imaging device that receives the light collected by the optical system and generates an imaging signal, and an optical system and an imaging device. And a transparent member having a refractive index that changes in accordance with the applied electric field.

[0023] According to this configuration, by applying an electric field to the transparent member, the refractive index of the transparent member changes, and the optical distance (optical path length) between the optical system and the imaging device is changed. Thereby, the imaging position of the light from the subject can be changed without mechanically and physically moving the lens barrel by the actuator. As a result, it is not necessary to provide an actuator, and the imaging apparatus can be downsized. In addition, the imaging position of light from the subject can be changed without a mechanical operation such as lever rotation. As a result, it is not necessary to provide a lens moving lever or the like, and the imaging apparatus can be downsized. In addition, since it is controlled by changing the refractive index of the transparent member, the mechanical movement of the lens It is possible to eliminate the sliding portion, to prevent the generation of wear powder due to sliding, and to realize an imaging device that does not deteriorate the image.

[0024] In the imaging device of the present embodiment, the refractive index of the transparent member continuously changes according to the applied electric field.

With this configuration, the imaging position of light from the subject can be continuously changed.

The imaging apparatus according to the present embodiment includes a control unit that performs autofocus adjustment by controlling the electric field to be applied and continuously changing the refractive index of the transparent member.

[0027] According to this configuration, autofocus can be performed by continuously changing the refractive index of the transparent member. As a result, there is no need to provide an autofocusing actuator, the imaging apparatus can be miniaturized, and the generation of abrasion powder associated with the operation of the actuator can be prevented.

The imaging apparatus according to the present embodiment includes a switching unit that switches the refractive index of the transparent member by controlling the applied electric field according to the imaging mode.

According to this configuration, it is possible to switch from the normal shooting mode force to the macro shooting mode by changing the refractive index of the transparent member. This makes it possible to switch to the macro shooting mode without mechanical operation such as lever rotation, so that the imaging device can be miniaturized and wear powder from the sliding portion can be prevented. be able to.

[0030] In the imaging device of the present embodiment, the transparent member includes transparent electrodes for applying an electric field on both the optical system side surface and the imaging element side surface.

[0031] According to this configuration, since the electric field can be directly applied to the transparent member by the transparent electrode, the structure can be simplified. In addition, since a transparent electrode is used, deterioration of the picked-up image, particularly color reproducibility, can be reduced.

[0032] In the imaging apparatus according to the present embodiment, the transparent member includes an infrared light limiting unit that limits transmission of infrared light on either the optical system side or the imaging element side.

[0033] According to this configuration, the transparent member has a filter function of cutting infrared light, so that it is not necessary to use a separate filter, and the number of parts can be reduced. As a result, the degree of freedom in designing the imaging device is increased, and the imaging device can be easily reduced in thickness.

[0034] In the imaging apparatus of the present embodiment, the transparent member is provided on the optical system side and the imaging element side. That is, an antireflection part for preventing light reflection is provided on the side opposite to the infrared light limiting part.

[0035] According to this configuration, it is possible to realize an imaging device in which ghost is hardly generated by preventing reflection of light.

[0036] In the imaging device of the present embodiment, a member whose refractive index increases when an electric field is applied is used as the transparent member.

[0037] According to this configuration, by applying an electric field to the transparent member, the refractive index of the transparent member is increased, and the optical path length can be substantially increased. As a result, for example, when auto force is not performed, when switching to macro shooting mode is not performed, and in normal shooting mode, it is not necessary to energize the transparent member, and power saving of the imaging device Can be realized.

A cellular phone device according to the present embodiment includes the above-described imaging device.

[0039] According to this configuration, by providing the imaging element that is focused by continuously changing the refractive index of the transparent member, an actuator that mechanically moves the lens barrel is not necessary, and the size can be reduced. An excellent portable terminal device with little image quality deterioration can be realized. Also, since there is no actuator, it is possible to improve the impact resistance of mobile terminal devices that do not generate noise. Further, since there is no movement of the lens, the movement of the optical axis accompanying the movement of the lens is eliminated. As a result, a portable terminal device with a camera with high convenience and reliability can be realized. In addition, by providing an image sensor that focuses by changing the refractive index of the transparent member, it is possible to switch to the macro shooting mode without mechanical operation such as lever rotation. It is possible to reduce the size of the device and to prevent generation of wear powder by the sliding portion. Also, instead of switching the lever, the shooting mode can be switched by a simple operation such as pressing a button, which eliminates the complication of mode switching and forgetting to switch. A portable terminal device can be realized.

Hereinafter, an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)

FIG. 1 is a perspective view showing an imaging apparatus according to the first embodiment of the present invention. The imaging device 8 includes a three-dimensional substrate 1, a lens 2, an aperture 3, a semiconductor imaging device 4, a transparent member 5, an FPC (flexible printed circuit) 15, a joint 16, a lens holder 20, and an adjustment ring 21. [0041] The three-dimensional substrate 1 includes a pedestal portion 7 and a lens barrel portion 17. The lens barrel portion 17 is provided on the upper portion of the pedestal portion 7 whose planar shape is a rectangle. Glass-reinforced PPA (polyphthalamide resin) or the like is used as the material of the three-dimensional substrate 1, and a black material is used to prevent light from being transmitted from the outside.

[0042] The pedestal portion 7 includes a terminal portion 7a provided for connection to the outside. Below the pedestal 7, an FPC 15 is provided for exchanging signals with external devices. The terminal portion 7 a is connected to a connection land 15 a formed on the FPC 15 by a joint portion 16. For example, the joint 16 is solder.

[0043] Inside the lens barrel portion 17, a resin lens 2 fitted in the lens holder 20 is disposed. The lens holder 20 is fixed to the outside of the lens barrel portion 17 through an adjustment ring 21 disposed on the outside thereof. The lens holder 20 is provided with a diaphragm 3. Inside the pedestal part 7 and the lens barrel part 17, the semiconductor image sensor 4 and the transparent member 5 are arranged.

[0044] The structure of the imaging device will be described in more detail with reference to FIG. FIG. 2 is a cross-sectional view of the imaging device 8 of FIG. 1 cut along a spring XX.

A partition wall 11 is formed on the inner side of the three-dimensional substrate 1 constituting the pedestal portion 7 and the lens barrel portion 17. An opening 10 is formed at the center of the partition wall 11. The upper and lower surfaces of the partition wall 11 surrounding the opening 10 form a plane parallel to each other. A transparent member 5 is disposed above the partition wall 11, and a semiconductor imaging element 4 is disposed below the partition wall 11. The transparent member 5 is fixed at a predetermined position on the upper surface of the partition wall 11 with an adhesive or the like. The opening 10 is formed in a rectangular shape corresponding to the imaging area of the semiconductor imaging device 4. All these components are structured to be assembled to the three-dimensional board 1!

Although not shown, a wiring pattern is formed on the back side of the pedestal 7 by electroless plating or the like. Further, a connection land for bare mounting the semiconductor image pickup device 4 is provided inside the three-dimensional substrate 1. The connection land and the terminal portion 7a are connected by a wiring pattern.

[0047] The semiconductor image pickup device 4 is, for example, a CCD or CMOS called a 1/4 inch UXGA type having about 2 million pixels. The semiconductor image pickup device 4 is face-down mounted on the three-dimensional substrate 1 and is electrically connected. Has been. This is because the mounting is performed without using a package in order to reduce the thickness of the imaging device. Face-down mounting uses, for example, SBB (Stud Bump Bond) or BGA (Ball Grid Array) using a bump formed of gold and a conductive adhesive (conductive material such as Ag paste) applied to the tip of the bump. ) Etc. are used. The semiconductor image sensor 4 is sealed with a sealant 9 after face-down mounting.

[0048] Video signals obtained by the semiconductor imaging device 4 and chip components (not shown) are output to the outside through electrical wiring. In addition, control signals are input from the outside by electric wiring, and power is supplied. These electric wirings are formed so as to pass through the wiring pattern and the connection land 15a of the FPC 15 shown in FIG. As shown in FIG. 2, a metal foil 14 is pasted on the back surface of the FPC 15 in order to prevent intrusion of visible light / infrared light from the back surface into the semiconductor image sensor 4.

The lens 2 built in the lens barrel portion 17 includes two aspheric lenses (hereinafter abbreviated as “lenses”) 2a and 2b having different optical characteristics. The lenses 2a and 2b are fitted in the lens holder 20 so that a certain positional relationship can be maintained. Screws 20a and 21a that are screwed to each other are formed on the outer periphery of the lens holder 20 and the inner periphery of the adjustment ring 21 arranged on the outer side thereof, so that the optical axis position of the lens holder 20 can be adjusted. ing.

Next, the configuration of the transparent member 5 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the transparent member 5. The transparent member 5 includes a base part 53, an electrode 51a, an electrode 51b, an IR (Infra Red) film 50 that is an infrared light limiting part, and an AR film 52 that is an antireflection part.

[0051] The base part 53 is made of a material whose refractive index changes when an electric field is applied. For example, lithium niobate can be used. For example, an optical crystal (KTN crystal) made of potassium, tantalum, niobium, or oxygen can be used.

The electrodes 51 a and 51 b are provided on both surfaces of the base material portion 53, respectively, and apply an electric field to the base material portion 53. The electrodes 51a and 51b are configured by a transparent electrode such as an indium tin oxide (ITO) film. Electrodes 51a and 51b are connected to an external DSP (Digital Signal) via FPC15.

And the like, and an electric field is applied to the base member 53 by applying a voltage to the electrodes 51a and 51b. In this case, the DSP It functions as a control unit that performs single-point control, and controls the voltages of the electrodes 51a and 51b to continuously change the refractive index of the base member 53.

The IR film 50 is provided below the electrode 51a and includes a multilayer film for limiting the transmission of infrared light. The IR film 50 has a transmittance of about 93% or more with respect to a visible light region having a wavelength of about 400 nm to 800 nm, and has a sufficiently low transmittance for other bands. The IR film 50 includes, for example, a multilayer film such as silicon dioxide and titanium oxide (TiO 2).

The AR film 52 is provided on the surface of the IR film 50 on the opposite side of the base material portion 53. AR membrane

52 prevents light reflection. The AR film 52 includes a multilayer film such as magnesium fluoride (MgF 3), titanium oxide (TiO 2), and zirconium oxide (ZrO 2).

[0055] The configuration and the number of laminated layers of the IR film 50 and the AR film 52 can be appropriately selected depending on the visible light region and the characteristics relating to transmission or reflection outside the region. Further, in the present embodiment, the IR film 50 is disposed on the imaging element side of the transparent member 5, but may be disposed on the optical system side opposite to the imaging element side. In the present embodiment, the AR film 52 may be disposed on the force S disposed on the optical system side of the transparent member 5 and on the image sensor side. In the present embodiment, the transparent member 5 is provided with the IR film 50 and the AR film 52 together with the electrode 51a and the electrode 51b. However, the IR film 50 and the AR film 52 are provided on the other base material. Is also possible.

[0056] Next, an optical system of the image pickup apparatus, which is effective in the present embodiment having the above-described configuration, will be described. Light from the subject passes through a diaphragm 3 provided in the center of the lens holder 20 shown in FIG. 2, is condensed by the lens 2, enters the semiconductor image sensor 4 through the transparent member 5, and forms an image. Aperture 3 is designed so that the opening becomes wider toward the subject side. This is to prevent light incident on the lens 2 from striking the wall surface of the diaphragm 3 in the optical axis direction and being scattered, thereby preventing unnecessary light from entering the lens.

[0057] For the lens 2, a resin satisfying required optical characteristics such as transmittance and refractive index is used. In the present embodiment, the lens 2 is formed by injection molding, for example. The lens 2 is composed of two lenses 2a and 2b, and can form a subject farther than a predetermined distance without performing autofocus. In the present embodiment, for example, a lens in a focus (pan focus) mode is provided for a subject farther than about 30 cm from the imaging device. And the subject is imaging If it is closer than about 30cm from the device, it will be focused by performing an autofocus operation, as described in detail later. The configuration and characteristics of the lens can be selected as appropriate.

The light from the subject passes through the lens 2 and reaches the transparent member 5. Then, the IR film 50 provided on the transmissive member 5 shown in FIG. 3 restricts the transmission of infrared light / ultraviolet light in the light from the subject, and the visible light is incident on the semiconductor imaging device 4. Although not shown, the incident light passes through a micro lens or a lens called an on-chip lens provided on the surface of the light receiving surface of the semiconductor image sensor 4 and passes through a dye-based color filter therebelow to be a photodiode. Is converted into a required electrical signal. As a result, the semiconductor image sensor 4 outputs, for example, an image signal having a screen aspect ratio of 4: 3 and a frame rate of 30 per second.

[0059] As described above, the lens 2 is configured to focus on a subject whose distance from the subject is more than about 30 cm. It is necessary to increase the distance between the lens 2 and the light receiving surface of the semiconductor image sensor 4. These relationships are known as Newton's equations. In other words, if the distance between the subject and the lens is a, the distance between the lens and the imaging position is b, and the focal length of the lens is f, equation (1) holds.

(l / a) + (l / b) = (l / f) ...... (1)

[0060] According to equation (1), when the focal length f of the lens 2 is constant, the distance b between the lens and the imaging position increases as the distance a to the subject decreases. Therefore, when the distance between the subject and the lens is short, it is necessary to increase the distance between the lens 2 and the light receiving surface of the semiconductor image sensor 4 in order to form an image of the subject on the light receiving surface of the semiconductor image sensor 4. The power of auto-focusing this distance adjustment automatically.

Conventionally, auto focus has been performed by moving the entire lens so that the physical distance from the semiconductor imaging device is increased by an actuator. On the other hand, in the present embodiment, the optical adjustment from the lens 2 to the semiconductor image sensor 4 is performed using the refractive index adjustment function of the transparent member 5 as described below without physically moving the lens. The long length (optical path length) is made substantially longer, and thus autofocus is performed.

[0062] The optical path length L is expressed as follows, where nd is the refractive index of the transmitting medium and t is the length of the transmitting medium. It is expressed by (2).

L = nd * t (2)

According to equation (2), in order to increase the optical path length L, the refractive index may be increased. In the present embodiment, the refractive index of the transparent member 5 arranged between the lens 2 and the semiconductor image sensor 4 is changed in order to increase the optical path length from the lens 2 to the semiconductor image sensor 4 during autofocus. . As a result, by adjusting the optical path length without moving the lens 2, autofocus is achieved.

FIG. 4 is a characteristic diagram showing the relationship between the electric field applied to the transparent member 5 and the refractive index in the present embodiment. When no electric field is applied (E = 0), the refractive index is nd.

The refractive index when 1 field E is applied is nd. Here, the linear change in applied electric field and refractive index is called the first-order electro-optic effect (Pockels effect), which has the effect that the refractive index change is proportional to the square of the applied electric field. This is called the second-order electro-optic effect (Kerr effect). In the present embodiment, the Kerr effect that allows a large change in refractive index is used. However, the present invention is not limited to this. For example, it is possible to use a transparent member in which the relationship between the applied voltage and the refractive index is not continuous.

As described with reference to FIG. 2, a voltage is also applied to the transparent member 5 disposed between the lens 2 and the semiconductor imaging device 4 through the FPC 15 as an external circuit force, and the electrodes 51a, An electric field is applied to the base material portion 53 through 51 b. Then, as shown in FIG. 4, when the electric field E is applied to the base part 53 of the transparent member 5, the refractive index of the base part 53 becomes the nd force,

Change to 2 1. In this case, the refractive index is nd <nd.

The optical path length between 2 and the semiconductor image sensor 4 becomes longer. As a result, the optical path length is changed without mechanically moving the lens 2. Thus, by changing the applied voltage, the refractive index is continuously changed, and a required optical path length is set. As a result, even if the lens 2 does not actually move in the optical axis direction, the same result as that in which the lens 2 continuously moves in the optical axis direction is produced. Accordingly, it is not necessary to perform the focusing operation by driving the actuator 41 shown in FIG. 6 and moving the lens barrel 43 together with the lens 42 in the direction of the optical axis as in the prior art. In the present embodiment, various methods such as a so-called hill climbing method can be applied to the focusing sequence. [0066] As described above, according to the present embodiment, by applying an electric field to the transparent member 5, the refractive index of the transparent member 5 changes, and the optical system and the semiconductor image pickup device 4 are changed. The optical distance (optical path length) is changed substantially continuously. As a result, the image forming position can be continuously changed without mechanically and physically moving the lens barrel by the actuator. As a result, it is not necessary to provide an actuator, and the imaging device 8 can be downsized. In addition, since the lens 2 does not move, the mechanical sliding portion can be eliminated, the generation of wear powder due to sliding can be prevented, and an image pickup apparatus free from image deterioration can be realized.

[0067] Further, according to the present embodiment, since the lens 2 does not move mechanically and physically in the optical axis direction, the lens 2 moves in a direction perpendicular to the optical axis of the image, or the image is inclined with respect to the imaging surface. (Flip) does not occur and autofocus performance is improved.

[0068] (Second Embodiment)

FIG. 5 is a plan view of a portable terminal device according to the second embodiment of the present invention. The portable terminal device 30 is equipped with an imaging device with an autofocus function that is effective in the first embodiment of the present invention.

As shown in FIG. 5, the mobile terminal device 30 according to the present embodiment is a foldable mobile terminal device including an upper housing 31 and a lower housing 32, and the upper housing 31 is in use. The lower casing 32 is opened, and the upper casing 31 and the lower casing 32 are folded when not in use. By connecting the upper housing 31 and the lower housing 32 via the hinge 35, the portable terminal device 30 is configured to be foldable. The upper housing 31 includes a speaker 33, a liquid crystal display screen 34, a transmission / reception antenna 36, and an imaging device 38. The lower housing 32 includes an input key 37 and a microphone 39. The input key 37 has an autofocus input key 37a.

The imaging device 38 includes the imaging device with an autofocus function according to the first embodiment. In this case, the imaging direction of the imaging device 38 is perpendicular to the paper surface of FIG.

Yes

[0071] When the autofocus input key 37a is pressed halfway, the imaging device 38 performs focusing by autofocus. Then, the blinking display displayed on the liquid crystal display screen 34 changes to a lighting display, and the user is notified of the in-focus state. In this state, enter key 37a When is further pressed, an imaging operation is performed, and the captured image is displayed on the liquid crystal display screen 34. Further, the imaging device 38 is set so as to be able to take an image with pan focus at the time of activation. Therefore, when autofocus is not required, the image pickup device 38 takes an image of the subject by pan focus by pressing the input key 37a without pressing it halfway.

As described above, in the present embodiment, since the subject is imaged with pan focus in the normal shooting mode (pan focus mode) that is generally used frequently, an electric field is applied to the transparent member 5 shown in FIG. Not applied. As a result, the power consumption of the mobile terminal device 30 can be kept low.

In the present embodiment, as already described in the first embodiment, there is no need to provide an actuator as in the prior art, and thus the mobile terminal device 30 is reduced in size and thickness. In addition, since autofocus is performed by applying a voltage to the transparent member 5, the mobile terminal device 30 that requires a mechanism for mechanically and physically moving the lens 2 is reduced in weight, and the mobile terminal device 30 is dropped. Improves the impact resistance against. In addition, since the lens 2 does not move mechanically and physically, the problem of image quality degradation due to dust generation accompanying the movement of the lens can be solved.

[0074] (Third embodiment)

Next, an imaging device according to a third embodiment will be described. The basic configuration of the imaging device of the third embodiment is the same as that of the imaging device of the first embodiment (see Figs. 1 to 4), but it is based on a DSP connected via the FPC15. The control details are different. In the imaging apparatus according to the third embodiment, the DSP functions as a switching unit that switches the shooting mode, and is applied to the base unit 53 by controlling the voltage applied to the electrodes 51a and 51b. Control the electric field of the electric field! /, And switch the refractive index of the base 53 according to the shooting mode.

[0075] Similar to the first embodiment described above, the lens 2 is configured to focus on a subject whose distance to the subject is more than about 30 cm. In order to adjust the focal point, it is necessary to increase the distance between the lens 2 and the light receiving surface of the semiconductor image sensor 4. These relationships are known as Newton's equation (1) above.

[0076] According to equation (1), when the focal length f of the lens 2 is constant, the distance a to the subject is short. If so, the distance b between the lens and the imaging position becomes longer. Therefore, when the distance between the subject and the lens is short, it is necessary to increase the distance between the lens 2 and the light receiving surface of the semiconductor image sensor 4 in order to form an image of the subject on the light receiving surface of the semiconductor image sensor 4. This distance adjustment is necessary in the macro shooting mode in which shooting is performed at a position close to the subject.

Conventionally, in the macro photography mode, the entire lens is moved by a switching lever or the like so that the physical distance from the semiconductor image sensor increases. On the other hand, in the present embodiment, the optical length from the lens 2 to the semiconductor image sensor 4 is utilized by using the refractive index adjustment function of the transparent member 5 as described below without physically moving the lens. The length (optical path length) is substantially lengthened, and the mode is switched to the macro photography mode.

As shown in the above equation (2), in order to increase the optical path length L, the refractive index may be increased. In the present embodiment, when switching to the macro photography mode, in order to increase the optical path length from the lens 2 to the semiconductor image sensor 4, the transparent member 5 disposed between the lens 2 and the semiconductor image sensor 4 Change the refractive index. As a result, the macro shooting mode can be switched by adjusting the optical path length without moving the lens 2.

As described with reference to FIG. 2, a voltage is applied to the transparent member 5 disposed between the lens 2 and the semiconductor image pickup device 4 through an FPC 15 from an external circuit (not shown). An electric field is applied to the base member 53 through the electrodes 51a and 51b shown in FIG. Then, as shown in FIG. 4, when the electric field E is applied to the base material portion 53 of the transparent member 5, the refractive index of the base material portion 53 changes to nd force, nd. In this case, the refractive index is nd <nd.

1 2 1 2

The optical path length between the semiconductor 2 and the semiconductor image sensor 4 becomes longer. As a result, the optical path length is changed without mechanically moving the lens 2.

As described above, according to the imaging apparatus which is effective in the present embodiment, the refractive index of the transparent member 5 is changed by changing the voltage to be applied, and the required optical path length is set. As a result, the optical path length can be changed without rotating the lens moving lever and mechanically moving the lens, and the force S for switching between the normal shooting mode and the macro shooting mode can be obtained depending on whether or not an electric field is applied. As a result, there is no need to provide a conventional lever or the like, and the imaging device 8 can be downsized. In addition, since it is not necessary to mechanically move the entire lens 2 in the direction of the optical axis, the problem of image quality degradation due to dust generation can be solved. Become.

In this embodiment, the case of switching between the normal shooting mode and the macro shooting mode has been described, but the shooting mode may be switched between three or more shooting modes. In this case, it is possible to switch between three or more photographing modes by applying different voltages to the transparent member 5 to generate three or more refractive indexes.

[0082] (Fourth embodiment)

Next, a mobile phone device according to a fourth embodiment of the present invention will be described. The basic configuration of the imaging device of the fourth embodiment is the same as that of the mobile phone device of the second embodiment (see FIG. 5), but the mobile phone device of the fourth embodiment is The difference is that it has the macro shooting switching function described in the third embodiment. Note that the shooting direction in the macro shooting mode is also a direction perpendicular to the paper surface.

The imaging device 38 changes the shooting mode from the normal shooting mode to the macro shooting mode and from the macro shooting mode to the normal shooting mode in response to the repeated pressing of the shooting mode switching input key 37a. It is comprised so that it may switch. In addition, the imaging device 38 is set to be in the normal shooting mode when it is activated.

As described above, in the present embodiment, an electric field is not applied to the transparent member 5 shown in FIG. 3 in the normal photographing mode that is generally used frequently. As a result, the power consumption of the mobile terminal device 30 can be kept low.

[0085] Also, in this embodiment, as already described in the first embodiment, it is necessary to provide a conventional switching lever or the like! /, So it is necessary to consider the movement range of the lever. As a result, the mobile terminal device 30 such as a mobile phone is reduced in size and thickness, and the design of the mobile terminal device 30 can be simplified. Furthermore, since the shooting mode can be easily displayed on the liquid crystal display screen 34, the shooting mode can be confirmed on the liquid crystal display screen 34, and forgetting to switch the shooting mode can be prevented, improving the convenience of the mobile terminal device 30. The In addition, since the photographing mode is switched by applying a voltage to the transparent member 5 from the circuit of the mobile terminal device 30, it is necessary to provide a mechanism for mechanically moving the lens 2. It is possible to improve the impact resistance against dropping of the material. In addition, the lens 2 is not moved mechanically by rotating the lever. It is possible to solve the problem of image quality degradation due to the above.

In the present embodiment, the mobile phone has been described as the mobile terminal device. However, the mobile phone of the present embodiment is not limited to this configuration. The imaging device according to the present invention can be applied to various types of portable information devices. For example, the imaging apparatus according to the present invention can also be applied to PDAs (personal 'digital' assistants), personal computers, and portable information devices such as personal computer external devices.

Note that the present invention is not limited to the above-described embodiment, and can be implemented in various other modes.

[0088] The power of explaining the preferred embodiment of the present invention considered at the present time. It will be understood that various modifications can be made to the present embodiment, and the true spirit and scope of the present invention can be understood. It is intended that the appended claims cover all such variations that are within the scope Industrial Applicability

[0089] The image pickup apparatus that is effective in the present invention has autofocus without mechanically and physically moving a lens mechanism, and can switch the shooting mode, so that the image pickup apparatus can be downsized. It is. Also, by displaying the shooting mode on the liquid crystal display screen, forgetting to switch the shooting mode can be prevented. In addition, since the image pickup apparatus that is effective in the present invention can eliminate the mechanical sliding portion for moving the lens, dust generation can be prevented and the image quality of the image pickup apparatus can be prevented from deteriorating. In addition, since there is no moving part of the lens, it is possible to improve the impact resistance S and to improve the reliability of the imaging device. The imaging device according to the present invention has the effects as described above, and is useful as a camera or the like mounted on a portable terminal device or the like.

Claims

The scope of the claims

[1] an optical system that collects light from the subject;

An imaging element that receives light collected by the optical system and generates an imaging signal; and a transparent member that is provided between the optical system and the imaging element and has a refractive index that changes in accordance with an applied electric field; ,

An imaging apparatus comprising:

[2] The imaging device according to [1], wherein the refractive index of the transparent member continuously changes in accordance with an applied electric field.

[3] The imaging apparatus according to [2], further comprising a control unit that performs autofocus adjustment by controlling an electric field to be applied and continuously changing a refractive index of the transparent member.

[4] The imaging device according to [1] or [2], further comprising a switching unit that controls an electric field to be applied and switches a refractive index of the transparent member according to a photographing mode.

[5] The imaging device according to any one of [1] to [4], wherein the transparent member includes transparent electrodes for applying an electric field on both the optical system side surface and the imaging element side surface.

[6] The imaging device according to any one of [1] to [5], wherein the transparent member includes an infrared light limiting unit that limits transmission of infrared light on either the optical system side or the imaging element side. .

7. The imaging according to claim 6, wherein the transparent member includes an antireflection portion for preventing light reflection on the optical system side and the imaging element side on the side opposite to the infrared light limiting portion. apparatus

Yes

8. The imaging device according to claim 1, wherein the transparent member has a refractive index that is increased when an electric field is applied.

[9] A portable terminal device comprising the imaging device according to any one of claims 8 to 8.