WO2001026036A2

WO2001026036A2 - Imaging module for optical reader

Info

Publication number: WO2001026036A2
Application number: PCT/US2000/027289
Authority: WO
Inventors: Charles P. Barber; Carl W. Gerst; Vivian L. Hunter; Melvin D. Mccall; Bruce L. Hahn
Original assignee: Welch Allyn Data Collection, Inc.
Priority date: 1999-10-04
Filing date: 2000-10-04
Publication date: 2001-04-12
Also published as: WO2001026036A3; JP2003532944A; US20040195328A1; AU7992000A; WO2001026036A9; US7500614B2; CN1391680A; EP1226541A2; US7296751B2; US20070152055A1

Abstract

The present invention is an imaging module (10) including a frame (12) supporting various optical components and a circuit board (14), which, in one embodiment, carries essentially an entirety of illumination (16) and aiming (18) LEDs of the module. The frame may include resilient fingers (48) which enable the frame to receive certain optical components in a snap-fit arrangement. Further, the module may be arranged so that the outer walls (31) and (31') of the module provide a containment for preventing structural damage to sensitive and fragile internal components of the module.

Description

IMAGING MODULE FOR OPTICAL READER

Field of the Invention

The present invention relates to optical reading devices

in general and in particular to an apparatus for packaging

illumination optical elements, receive optical elements, and

signal processing elements of an optical reader.

Background of the Invention Currently available optical readers include illumination

elements, electronic signal processing circuits, image capture

circuits and decoding circuits that are carried by more than

one circuit board. For example, shown in U.S. Patent No.

5,780,834 is an optical reader having numerous circuit boards,

including an LED board for carrying illumination LEDs, an

"imaging board" carrying an image sensor and circuitry for

processing signals generated from the image sensor, and a

"mother board" carrying image capture and decoding circuitry.

U.S. Patent No. 5,521,366 describes a modular housing having a

rear printed circuit board, a front printed circuit board and

a LED circuit board on which LEDs are mounted.

Assembly of a prior art reader requires mounting of

separate circuit boards to separate internal structures of a

reader, and providing electrical connection between the multiple circuit boards. In addition to being difficult to

assemble, the multiple circuit board design imposes size

requirements on the optical reader housing in which the

electrical components are to be integrated.

There is a need for an easier to manufacture and lower

cost packaging apparatus for packaging optical and electrical

components of an optical reader.

Summary of the Invention According to its major aspects and broadly stated the

present invention is a module for packaging optical

illumination, optical receive, and electrical signal

processing components of an optical reader.

The module includes a frame which carries a printed

circuit board, preferably a printed circuit board (PCB) and

various optical components. In one embodiment, the frame

includes a back plate having a retainer for receiving an

optical lens barrel, and a recess for receiving and aligning

an image sensor which is carried by the PCB. The frame may

also include resilient fingers which enable the frame to

receive certain optical components of the module in an

adhesiveless snap-fitting arrangement.

According to a preferred assembly method for assembling the module, the PCB is first mounted onto the frame's back

plate such that the image sensor of the PCB is received and

aligned by the recess of the back plate. Next, illumination

and aiming LEDs are soldered to the PCB to mount the LEDs . As

a space conserving measure, the LEDs may be mounted so that a

portion of rear surfaces of the illumination LEDs oppose a

portion of the top surface of the image sensor when mounted.

After the LEDs are mounted to the PCB, additional

components are incorporated in the module. In a preferred

embodiment, a lens barrel is incorporated in the retainer,

then an aperture plate having domed apertures for shaping

light rays emanating from the aiming LEDs is placed over the

LEDs. Finally, an optical plate having diffusers for

diffusing light rays emanating from the illumination LEDs is

snap-fit into the frame.

In addition to having diffusers for diffusing

illumination light, the optical plate may also include optical

elements for imaging light from the apertures onto a target

defined by a reader's field of view. In one embodiment of the

invention, the aiming LEDs and their associated optics project

a solitary horizontal aiming line onto a target in a field of

view.

The printed circuit board may be a full function printed circuit board which carries a solid state image sensor and

essentially the entirety of electronic circuitry required for

supporting essentially all of the processing and control

operations to be performed by the optical device in which the

module is to be incorporated. Circuitry incorporated in the

single PCB includes signal processing circuitry for processing

signals generated from the image sensor, image capture

circuitry for storing image data, and decoding and/or

recognizing circuitry for decoding and/or recognizing indicia

represented in image data that has been stored.

In order to accommodate the full function circuit board,

the rear surface of the frame's back plate should be made to

have a central recess for aligning and receiving the image

sensor, and peripheral recesses for accommodating circuit

elements such as electrical components and/or wiring which may

emanate from the front surface of the full function printed

circuit board.

These and other details, advantages and benefits of the

present invention will become apparent from the detailed

description of the preferred embodiment herein below.

Brief Description of the Drawings

For a fuller understanding of the nature and objects of the invention, reference should be made to the following

detailed description of a preferred mode of practicing the

invention, read in connection with the accompanying drawings,

in which:

Fig. 1A is a front perspective assembly diagram

illustrating assembly of an image capture module according to

the invention;

Fig. IB is a rear perspective assembly diagram

illustrating assembly of an image capture module according to

the invention;

Fig 1C is a front perspective view of an assembled image

capture module according to the invention;

Fig. ID is a rear perspective view of an assembled image

capture module according to the invention;

Fig. IE is a representation of a preferred illumination

and aiming pattern projected by a module in accordance with

the invention;

Fig. IF is a block diagram for illustration of functional

and control features of the invention;

Figs. 2A - 21 are perspective views of various optical

reader housings in which the invention may be incorporated;

Fig. 3 is a side view of a prior art reader illustrating

a prior art multiple circuit board arrangement. Detailed Description of the Invention

An embodiment of an imaging module 10 according to the

invention is shown in Figs. 1A through ID. Imaging module 10

is specifically designed for use in an indicia reader such as

a bar code reader, an optical character recognition (OCR)

reader or in a reader having both bar code and OCR reading

capabilities. However, it will be understood that features of

module 10 may also find use in other devices requiring image

capture including video cameras, digital cameras, and medical

viewing instruments.

Module 10 includes a mounting frame 12 which is adapted

to receive both electrical components and optical components

of an imaging system. Specifically, mounting frame 12

receives a circuit board, such as a printed circuit board

(PCB) 14, illumination LEDs 16, aiming LEDs 18, aperture plate

24 and optical plate 26.

More specifically, the frame 12 includes a back plate 30

and sidewalls including top and bottom sidewalls 31 and side

sidewalls 31. Back plate 30 includes a recess 34 for

receiving a solid state image sensor chip 32 and a plurality

of pin holes 36 for receiving leads 38 of illumination and/or

aiming light sources, provided by LEDs 16 and 18. Back plate

30 further includes a retainer 40 for receiving a receive optics lens assembly 41, e.g. a lens barrel, which may be

installed in retainer 40 prior to or after any step in the

assembly process as described in greater detail below.

In assembling the module 10, PCB 14 is first mounted to

back plate 30 using screws 56 and frame 12 is oriented so that

an opening 13 is exposed. When PCB 14 is mounted to back

plate 30 the image sensor 32 carried by PCB 14 is received and

aligned by center recess 34 which is shaped complimentary with

the shape of image sensor 32 as shown. After mounting PCB 14

to frame 12, an assembler mounts illumination LEDs 16 and

aiming LEDs 18 to PCB 14.

To mount LEDs 16 and 18 to PCB 14, the leads 38 of LEDs

16 and 18 are pushed through aligned pin holes 36 and 54 of

back plate 30 and PCB 14, then the LEDs 16 and 18 are soldered

to PCB 14. Preferably, all of the LEDs 16 and 18 are

positioned in their respective pin holes before soldering. In

soldering LEDs 16 and 18, the rear surface 15 of PCB 14 should

be oriented for easy access by an assembler. To the end that

LEDs 16 and 18 remain in a desired orientation which is

substantially normal to PCB 14 during soldering, a standardly

known fixture (not shown) shaped to receive LEDs 16 and 18 can

be temporarily applied over LEDs 16 and 18 through the

soldering process . An important feature of the imaging module is that leads

38 of the illumination LEDs 16 are installed in a nearly

abutting relation to sides 33 of image sensor 32 such that a

portion of rear surfaces 19 of LEDs 16 oppose a portion of a

front surface 33 of image sensor 32 when the LEDs 16 are

completely installed. This arrangement reduces the size of

the imaging module 12, enabling installation in smaller sized

optical readers.

After LEDs 16 and 18 are mounted onto PCB 14 in the

manner described above, the aperture plate 24 is mounted into

the frame 12, the frame having domes 42 which fit over the

aiming LEDs 18. The domes are preferably opaque to

substantially block all light emanating from aiming LEDs 18,

except light exiting the domes through slit apertures 43.

Slit apertures 43 should be formed so that a desired shaped

aiming pattern of illumination is projected onto a target, T.

Preferably, slit apertures 43 are shaped rectangularly so that

a horizontal line pattern is projected onto a target.

Aperture plate 24 further includes a number of cutaway

sections 46 providing clearance to allow the aperture plate to

be fitted over the illumination LEDs 16. The domes 42 and

cutaway sections 46 are formed so they do not contact LEDs 16.

In the embodiment shown, each LED is held in a desired orientation while being soldered, so that the flat surfaces of

LED bases 17 are biased against the flat surface of back plate

30 during the assembly process. In a further aspect, aperture

plate 24 includes a shroud 58 for preventing light transmitted

by the LEDs 16 and 18 from interfering with the receive

optical system of the module.

After aperture plate 24 is placed over LEDs 16 and 18 and

moved toward back plate 30, an optical plate 26 is snap-fitted

into the opening 13 of the frame 12. Optical plate 26

includes diffusers 27 for diffusing light emanating from the

illumination LEDs. In addition to having diffusers 27 formed

on a front surface thereof optical plate 26 may further have

wedges 28 formed on an inner surface thereof. Wedges 28

direct light from LEDs 16 toward corners of a target T so as

to improve the uniformity of a target's illumination.

Resilient fingers 48 having hook ends 49 are formed in

the top or side sidewalls 31 of frame 12 to enable snap-

fitting of the optical plate 26 onto frame 12. In the

embodiment shown, the optical plate 26 is snap-fitted onto the

frame 12 by pulling back the resilient fingers 48, pushing the

optical plate toward the back plate 30, then releasing the

fingers 48 to lock plate 26 in position inside module 10. The

aperture plate 24 includes spacers 52 which operate to bias aperture plate 24 toward back plate 30 when optical plate 26

is snap fitted onto frame 12. The spacers 52 further transfer

the force imparted by fingers 48 on optical plate 26 to the

aperture plate 24, securing both the aperture plate 24 and

optical plate 26 inside frame 12 without the use of adhesives

or outside mechanical securing means, such as screws or pins.

Representations of an illumination pattern and an aiming

pattern which may be projected by the emit optical system of

module 10 are shown in Fig. IE. In Fig. IE, area 72

represents the region about a target area T illuminated by

illumination LEDs 16 and their associated optics while area 74

represents the region about a target area highlighted by

aiming LEDs 18 and their associated optics. In the embodiment

of Fig. IE aiming LEDs 18 and their associated optics project

a solitary horizontal aiming line 74 onto a target area T.

The straight line aiming pattern of Fig. IE may be

generated by manufacturing plate 26 so that horizontally

oriented cylindrical lenses 25 are formed on the outer surface

of optical plate 26 as is shown in Fig. 1A. Horizontally

oriented cylindrical lenses 25 are formed so that when plate

26 is applied over LEDs 18 lenses 25 are aligned coextensively

and forwardly relative to slit apertures 43 in order to

collimate and thereby image light from slit apertures 43 onto a target T, defined by a module's field of view.

An important feature of the invention is that essentially

all the illumination elements of a reader in which module 10

is to be incorporated are included on a single circuit board

shown as being provided by PCB 14. This is in contrast to the

design of the prior art reader shown in Fig. 3 in which

illumination elements and image sensing elements are spread

out over several circuit boards. In the prior art device

shown in Fig. 3, an aiming illumination source 53 is mounted

to a first circuit board 54, illumination LEDs are mounted to

a second circuit board 56, while image sensor 32 is mounted to

a third circuit board 58. The assembly of a module of this

prior art design is difficult and requires material components

not required by the design of the present invention including

circuit boards 54, 56 and electrical connectors between the

circuit boards such as connector 57. Providing a single

circuit board that carries an image sensor, illumination LEDs,

and aiming LEDs significantly simplifies assembly, reduces

material consumption and thereby reduces the overall cost of

producing the module.

Another important aspect of the invention, in one

embodiment, is that essentially all electronic circuitry

supporting the data processing operations required of module 10 are located on single, full function PCB 14, including

circuitry for processing signals generated from image sensor

32, circuitry for capturing image data into a memory device,

circuitry for decoding and/or recognizing indicia represented

in captured image data. Circuitry for supporting serial

transfers of data to peripheral devices may also be carried by

PCB 14.

The all in one PCB arrangement of the present invention

is in contrast to the traditional design in the prior art

wherein circuitry for processing signals from an image sensor,

circuitry for capturing and decoding image data and circuitry

supporting serial interfacing with external devices are spread

out over more than one circuit board.

In the design of the prior art reader shown in Fig. 3, a

first vertically oriented circuit board 56 is provided for

carrying circuitry for processing signals generated by an

image sensor 32 and a second horizontally oriented circuit

board 60, known as a "mother board" is provided for carrying

circuitry for storing image data and for decoding symbologies .

The one PCB design of the present invention provides

numerous advantages over the two PCB design of the prior art.

The multiple circuit board arrangement of the prior art

requires a complex assembly procedure wherein the first circuit board 58 is mounted to a first internal structure of

the reader in which it is incorporated, the second circuit

board is mounted to a second internal structure of the reader,

and then the two circuit board are electrically connected.

The separate horizontal and vertical orientations of the two

circuit boards 58, 60 is inefficient in terms of space

consumption and imposes restrictions on the configurations of

housings in which the reader optical and electrical components

may be incorporated. The one full function PCB design of the

present invention does not exhibit these disadvantages.

To the end that essentially the entirety of the required

electronic circuitry of an optical reader can be packaged into

a single printed circuit board, the back surface of the

frame's back plate 30 should be configured to accommodate

electrical components that will extend forward from the front

surface 15 of PCB 14. Accordingly it is seen that the rear

surface of back plate 30 includes a central recess 34 for

aligning and receiving solid state image sensor 32 and

peripheral recesses 35 for accommodating electrical circuitry

such as components and/or conductors which may protrude from

the front surface of PCB 14.

In addition to the features that have been described

herein above, it will be seen that additional benefits are yielded by features relating to the overall shape and

configuration of module 10. As best seen in Figs. 1C and ID,

sidewalls 31 and 31' of frame 10, together with PCB 14 and

plate 26 define a module having a substantially cubic

rectangular overall form. The cubic rectangular form is

highly space efficient relative to the form of certain optical

reader imaging modules in the prior art. With reference again

to Fig. 3 it is seen that the form of prior art imaging module

52 is highly irregular in that it contains members such as

member 53 and member 56 that protrude extraneously from the

major body of module 52. The volume conserving cubic

rectangular configuration of the module of the present

invention facilities incorporation of the module into optical

reader housings of smaller interior volume than was possible

with the irregular imaging module designs of the prior art.

The volume conserving cubic rectangular form of module, in

addition to facilitating incorporation of the module into a

smaller volume optical reader housings, renders the module

easier to package in containers containing several of the

modules .

Another feature relating to the outer configuration of

module 10, is that the defined outer walls of module 10 serve

as a containment for protecting and preventing damage to relatively fragile and sensitive internal components of the

module. In the embodiment shown in Figs. 1A-1D, substantially

all fragile sensitive components, including all light sources

of module 10, and image sensor 32, are disposed inside a

substantially rigid containment structure defined by sidewalls

31, 31' and PCB 12 and the combination of sidewalls 31, 31'

and optical plate 26.

The substantially rigid containment of sensitive internal

components of the module provided by the combination of

sidewalls 31, 31' and PCB 14 and/or the combination of

sidewalls 31, 31' and optical plate 26 eliminate the need to

package the module with shock absorbing material such as

bubble paper or foam particles during transport and allows the

module to be safely transported from one location to another

without substantial risk of damage to sensitive internal

components .

Significantly, two of the rigid planar members defining

the containment structure, namely PCB 14 and optical plate 26,

provide functions important to the operation of module 10

other than the containment function. Arranging PCB 14 and

optical plate 26 so that they provide containment functions in

addition to the respective electrical signal processing and

optical functions reduces the cost of module 10 relative to the cost of a module in which separate rigid members are

arranged to provide the containment functions provided by PCB

14 and/or plate 26 in module 10.

A block diagram illustrating one type of optical reading

device in which the invention may be incorporated is described

with reference to Fig. IF.

Optical reader 110 includes an illumination assembly 120

for illuminating a target object T, such as a ID or 2D bar

code symbol, and an imaging assembly 130 for receiving an

image of object T and generating an electrical output signal

indicative of the data optically encoded therein.

Illumination assembly 120 may, for example, include an

illumination source assembly 122, such as one or more LEDs,

together with an illuminating optics assembly 124, such as one

or more lenses, reflectors or other optical elements such as

diffusers and wedges 27 and 28, for directing light from light

source 122 in the direction of target object T. The

illumination assembly in the embodiment of Figs. 1A-1D is

provided entirely by LEDs 16. Illumination assembly 120 may

be eliminated if ambient light levels are certain to be high

enough to allow high quality images of object T to be taken.

Imaging assembly 130 may include an image sensor 132, such as

a ID or 2D CCD, CMOS, NMOS, PMOS , CID OR CMD solid state image sensor, together with an imaging optics assembly 134 for

receiving and focusing an image of object T onto image sensor

132. The array-based imaging assembly shown in Fig. IF may be

replaced by a laser array based imaging assembly comprising

multiple laser sources, a scanning mechanism, emit and receive

optics, at least one photodetector and accompanying signal

processing circuitry.

Optical reader 110 of Fig. IF also includes programmable

control unit 140 which preferably comprises an integrated

circuit microprocessor 142 and an application specific

integrated circuit (ASIC 144) . The function of ASIC 144 could

also be provided by field programable gate array (FPGA) .

Processor 142 and ASIC 144 are both programmable control

devices which are able to receive, output and process data in

accordance with a stored program stored in memory unit 145

which may comprise such memory elements as a read/write random

access memory or RAM 146 and an erasable read only memory or

EROM 147. RAM 146 typically includes at least one volatile

memory device but may include one or more long term non-

volatile memory devices. Processor 142 and ASIC 144 are also

both connected to a common bus 148 through which program data

and working data, including address data, may be received and

transmitted in either direction to any circuitry that is also connected thereto. Processor 142 and ASIC 144 differ from one

another, however, in how they are made and how they are used.

More particularly, processor 142 is preferably a general

purpose, off-the-shelf VLSI integrated circuit microprocessor

which has overall control of the circuitry of Fig. 2, but

which devotes most of its time to decoding image data stored

in RAM 146 in accordance with program data stored in EROM 147.

Processor 144, on the other hand, is preferably a special

purpose VLSI integrated circuit, such as a programmable logic

or gate array, which is programmed to devote its time to

functions other than decoding image data, and thereby relieve

processor 142 from the burden of performing these functions.

The actual division of labor between processors 142 and

144 will naturally depend on the type of off-the-shelf

microprocessors that are available, the type of image sensor

which is used, the rate at which image data is output by

imaging assembly 130, etc. There is nothing in principle,

however, that requires that any particular division of labor

be made between processors 142 and 144, or even that such a

division be made at all. This is because special purpose

processor 144 may be eliminated entirely if general purpose

processor 142 is fast enough and powerful enough to perform

all of the functions contemplated by the present invention. It will, therefore, be understood that neither the number of

processors used, nor the division of labor therebetween, is of

any fundamental significance for purposes of the present

invention.

With processor architectures of the type shown in Fig.

IF, a typical division of labor between processors 142 and 144

will be as follows. Processor 142 is preferably devoted

primarily to such tasks as decoding image data, once such data

has been stored in RAM 146, recognizing characters represented

in stored image data according to an optical character

recognition (OCR) scheme, handling menuing options and

reprogramming functions, processing commands and data received

from control/data input unit 139 which may comprise such

elements as trigger 174 and keyboard 178 and providing overall

system level coordination. Processor 144 is preferably

devoted primarily to controlling the image acquisition

process, the A/D conversion process and the storage of image

data, including the ability to access memories 146 and 147 via

a DMA channel. Processor 144 may also perform many timing and

communication operations. Processor 144 may, for example,

control the illumination of LEDs 122, the timing of image

sensor 132 and an analog-to-digital (A/D) converter 136, the

transmission and reception of data to and from a processor external to reader 110, through an RS-232, a network such as

an ethernet, or a serial bus such as USB, (or other)

compatible I/O interface 137 and the outputting of user

perceptible data via an output device 138, such as a beeper, a

good read LED and/or a display monitor which may be provided

by a liquid crystal display such as display 182. Control of

output, display and I/O functions may also be shared between

processors 142 and 144, as suggested by bus driver I/O and

output/display devices 137' and 138' or may be duplicated, as

suggested by microprocessor serial I/O ports 142A and 142B and

I/O and display devices 137" and 138'. As explained earlier,

the specifics of this division of labor is of no significance

to the present invention.

In accordance with a feature of one embodiment of the

invention described with reference to Figs. 1A-1D, essentially

all of the electrical signal processing components described

with reference to Fig. IF may be carried by a single circuit

board, PCB 14, as is indicated by dashed- in border 14, of Fig.

IF. In order to incorporate essentially all of the electrical

signal processing components of Fig. IE onto a single PCB 14,

it is normally necessary to integrate several electrical

components into a reduced number of electrical components.

For example, using known integrated circuit fabrication techniques, components 142, 144, 146 and 147 and interfaces

137, 137' and 137" can be incorporated in a single integrated

circuit chip of reduced size. Further, as explained in an

article by Eric R. Fossum entitled Digi tal Camera System on a

Chip, IEEE Computer Society (IEEE Micro), Volume 18, Number 3,

May/June 1998, image sensor 132, signal processing components

135, 136, and components 142, 144, 146, 147, 137, 137' and

137" may be incorporated in a single integrated circuit of

reduced size.

Figs . 2A through 2H show examples of types of housings in

which the present invention may be incorporated. Figs. 2A and

2B show a ID optical reader 110-1, while Figs. 2C-2H show 2D

optical readers 110-2, 110-3 and 110-4. Housing 112 of each

of the optical readers 110-1 through 110-4 has incorporated

therein is adapted to be graspable by a human hand and at

least one trigger switch 174 for activating image capture and

decoding and/or image capture and character recognition

operations. Readers 110-1, 110-2 and 110-3 include hard-wired

communication links 178 for communication with external

devices such as other data collection devices or a host

processor, while reader 110-4 includes an antenna 180 for

providing wireless communication with an external device such as another data collection device or a host processor.

In addition to the above elements, readers 110-3 and 110-

4 each include a display 182 for displaying information to a

user and a keyboard 184 for enabling a user to input commands

and data into the reader.

Any one of the readers described with reference to Figs .

2A through 2H may be mounted in a stationary position as is

illustrated in Fig. 21 showing a generic optical reader 110

docked in a scan stand 190. Scan stand 190 adapts portable

optical reader 110 for presentation mode scanning. In a

presentation mode, reader 110 is held in a stationary position

and an indica bearing article is moved across the field of

view of reader 110.

While this invention has been described in detail with

reference to a preferred embodiment, it should be appreciated

that the present invention is not limited to that precise

embodiment. Rather, in view of the present disclosure which

describes the best mode for practicing the invention, many

modifications and variations would present themselves to those

skilled in the art without departing from the scope and spirit

of this invention, as defined in the following claims.

Claims

What is claimed:

1. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor carried by said circuit

board, and at least one illumination light source for

illuminating a target area, said module being characterized in

that both of said image sensor and said at least one

illumination light source are mounted on said circuit board.

2. The module of claim 1, further including a back plate

receiving and aligning of said image sensor carried by said

circuit board.

3. The module of claim 1, further including a back plate

receiving said image sensor, wherein said at least one

illumination light source includes a lead extending through

said back plate.

4. The module of claim 1, wherein at least one light

source comprises four vertically and horizontally spaced apart

LEDs mounted to said circuit board.

5. The module of claim 1, wherein top, bottom, and side

surfaces of said module are defined by sidewalls of said frame, and wherein a back surface of said module is defined by

said circuit board.

6. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, at least one

illumination light source, and at least one aiming light

source, said module being characterized in that each of said

image sensor, at least one illumination light source and said

at least one aiming light source are mounted on said circuit

board.

7. The module of claim 6, further including a back plate

receiving and aligning of said image sensor carried by said

circuit board.

8. The module of claim 6, further including a back plate

receiving said image sensor, wherein said at least one

illumination light source includes a lead extending through

said back plate.

9. The module of claim 6, wherein at least one light

source comprises four vertically and horizontally spaced apart

LEDs mounted to said circuit board.

10. The module of claim 6, wherein top, bottom, and side

surfaces of said module are defined by sidewalls of said

frame, and wherein a back surface of said module is defined by

said circuit board.

11. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, and at least one

illumination light source for illuminating a target area, said

module being characterized in that said module includes at

least one planar optical component, and wherein said frame

comprises sidewalls having resilient fingers formed therein

for receiving and securing said optical component in said

frame in a stationary position in said frame.

12. The module of claim 11, wherein said one planar

optical component carries a diffuser for diffusing light from

said at least one illumination light source.

13. The module of claim 11, wherein said at least one

illumination light source comprise four vertically and

horizontally spaced apart LEDs, and wherein said planar

optical component carries four diffusers, each diffuser

diffusing light from one of said LEDs.

14. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, and at least one

illumination light source for illuminating a target area, said

module being characterized in that said circuit board carries

said image sensor and essentially all image sensor signal

processing circuitry and decoding circuitry of an optical

reader in which said module is to be incorporated.

15. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, and at least one

illumination light source for illuminating a target area, said

module being characterized in that said frame includes

substantially rigid top, bottom, and side sidewalls, and

wherein said sidewalls and said circuit board define outer

walls of said module.

16. The module of claim 15, wherein said sidewalls, and

said plate define a substantially cubic rectangular

configuration.

17. The module of claim 15, wherein said sidewalls and

said circuit board define a partially enclosed contained area,

and wherein said image sensor and said at least one illumination source are contained in said contained area so

that said image sensor and said sidewalls are structurally

protected by said sidewalls and said circuit board.

18. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, and at least one

illumination light source for illuminating a target area, said

module being characterized in that said frame includes a back

plate having a center recess for receiving and aligning said

image sensor.

19. The imaging module of claim 18, wherein said back

plate further includes at least one side recess for

accommodating electrical components emanating forwardly from

said circuit board.

20. An imaging module having a frame, a circuit board

mounted to said frame, an image sensor, and at least one

illumination light source for illuminating a target area, said

module being characterized in that said module further

includes a pair of aiming light sources, and a pair of slit

apertures disposed forwardly of said aiming light sources.

21. The module of claim 20, wherein said module includes

an aperture plate defining said slit apertures, said aperture

plate being disposed over said aiming light sources.

22. The module of claim 20, wherein said module includes

an aperture plate having domes fitable on said aiming light

sources, wherein said slit apertures are defined in said

domes .

23. The module of claim 20, wherein said module includes

a pair of lens elements disposed forwardly of said pair of

slit apertures for imaging said slit apertures onto a target.

24. The module of claim 20, wherein said lens elements

are formed on an optical plate received by said frame.

25. An imaging module having circuit board, an image

sensor carried by said circuit board and a light source having

leads, characterized in that said leads are substantially

abutted against a side of said image sensor and mounted to

said circuit board so that a portion of said light source

opposes a top surface of said image sensor, whereby space

consumed by said module is conserved.

26. An optical reader comprising an imaging assembly

having a field of view defining a target, and an illumination

assembly characterized in that said an illumination assembly

includes:

at least two rows of LEDs, each row comprising at

least two LEDs;

an illumination optical assembly positioned forward

of said LEDs, wherein said illumination optical assembly

comprises diffusers for diffusing light from said LEDs, and

wedges for directing light form said LEDs toward corners of

said target.

27. The reader of claim 26, wherein said optical

assembly is provided on an optical plate having light entry

and light exit surfaces, wherein said diffusers are formed on

said light exit surface and wherein said wedges are formed on

said light exit surface.

28. The reader of claim 26, wherein there is a one to

one correspondence between diffusers and LEDs of said

illumination assembly.