JPH08307597A - Contact type image sensor - Google Patents

Abstract

PURPOSE: To provide a contact type image sensor facilitating the positioning of a rod lens array and improving an S/N ratio by eliminating stray light. CONSTITUTION: This sensor is provided with plural LED chips 29 irradiating an original 33, etc., a holding frame 20 placing the substrate 28 on which the LED chips 29 are mounted and being provided with an optical path part passing the irradiation light from the LED chips 29, a frame 15 in which a recessed part 17 storing the holding frame 20 and storing the rod lens array 19 converging the light beam reflected on the original 33, etc., is formed and a light receiving sensor 32 receiving the light beam converged through the rod lens array 19. In the holding frame 20, a positioning part 23 performing the positioning between the frame 15 and the holding frame 20 is formed. By the holding frame 20, the rod lens array 19 is held between the wall surface of the recessed part 17 and the wall surface of the holding frame 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type image sensor for irradiating a document or the like to read the document or the like.

[0002]

2. Description of the Related Art A conventional contact image sensor will be described below with reference to the drawings. FIG. 4 is a cross-sectional view of the contact image sensor of the first conventional example. In FIG. 4, 1 is a frame made of aluminum or the like, 2
Is an LED chip arranged on an inclined surface provided inside the frame 1 to irradiate a document 8 and the like described later, and 3 is a frame 1
A glass plate which is disposed on the lower surface of the glass plate and which receives the light emitted from the LED chip 2 and contacts the document 8 and the like, 4 is an opening provided in the frame 1, 5 is a document provided below the opening 4. A rod lens array 8 for converging reflected light rays, such as 8 is a circuit board disposed on the upper part of the frame 1 for processing a signal of a light receiving sensor 7 described later. The light receiving sensor 7 is arranged on the lower surface of the circuit board 6. The photodetector receives the focused light beam of the rod lens array 5. Reference numeral 8 is a document or the like which is brought into contact with the glass plate 3 and irradiated.

The operation of the conventional contact image sensor constructed as described above will be described below. The light beam 9 emitted from the LED chip 2 is incident on the upper surface of the glass plate 3 in an oblique light state. The light beam 9 incident on the glass 3 is refracted and reaches the lower surface of the glass plate 3. On the other hand, on the lower surface of the glass plate 3, there are documents 8 and the like to be conveyed.
The light beam 9 reaching the lower surface irradiates the original 8 or the like and reflects it toward the upper surface of the glass plate 3 according to the information of the original 8 or the like. The reflected light beam 9 is focused by the rod lens array 5 provided on the lower side of the glass plate 3. Then, the focused light beam 9 is received by the light detection unit of the light receiving sensor 7, and photocarriers are generated and accumulated according to the amount of received light.

When a pulse signal, which is an operation signal, is input to the start signal input terminal of the light receiving sensor 7, the shift register is sequentially turned on from the first bit of the photodetector and output signals are taken out in time series. This signal is further electrically amplified and output as the final sensor output signal.

Next, in the configuration of the conventional image sensor, the operation when the optical axis of the rod lens array 5 is displaced from the predetermined position will be described. FIG. 5: is a figure explaining the stray light of the conventional image sensor. As shown in FIG. 5, when the rod lens array 5 arranged in the opening 4 is displaced from a predetermined position to the LED chip 2 side (direction of arrow B), the rod lens array 5 is reflected by the reading line portion of the document 8. The light ray 9 reaches the light receiving sensor 7 as transmitted light 9 ′ through the rod lens array 5. Then, the reflected light from other than the reading line portion normally reaches the substrate 6 as a transmitted light 10 ′ through the rod lens array 5 without affecting the light receiving sensor 7 and is absorbed and diffused, as shown by the light ray 10. .

However, since the mounting position of the rod lens array 5 is displaced, the transmitted light 10 'of the reflected light 11 interferes with the side wall of the opening 4 and is diffusely reflected, and a part of the stray light 1 is generated.
It becomes 1 ′ and reaches the light receiving sensor 7. Stray light 1
When 1'is generated, the S / N ratio of the sensor output is lowered at that portion, and the reproduction performance of image reading is extremely deteriorated. In particular, as shown in FIG. 5, when the rod lens array 5 is displaced toward the LED chip 2 side, the light ray 9 in the portion indicated by A in FIG. 4 becomes reflected light 11 to generate stray light 11 ′. Since the portion is close to the LED chip 2, the illuminance is high, and the reflected light 11 is also strong, so that the amount of stray light 11 ′ is naturally large and the S / N ratio is significantly reduced.

Therefore, in order to improve the S / N ratio, a structure as shown in FIGS. 6 and 7 has been proposed. FIG. 6 is a sectional view of the contact image sensor of the second conventional example, and FIG. 7 is a sectional view of the contact image sensor of the third conventional example. 6 and 7, those having the same functions as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 6, 1 is a frame, 2 is an LED chip, 3 is a glass plate, 4'is a first opening, 5 is a rod lens array, 6
Is a circuit board, 7 is a light receiving sensor, 8 is a document, and 12 is L.
It is a second opening through which the light beam 9 of the ED chip 2 passes. Reference numeral 13 denotes an optical path for diffusing and reflecting the light ray 9 that has passed through the second opening 12 and making it a light of a substantially uniform light quantity.
The light beam 9 is incident on only a predetermined portion of the glass plate 3 from the opening of the glass plate 3 on the side of the glass plate 3. In the second conventional example shown in FIG. 6, the portion A of the glass plate 3 is covered with the frame 1 so that only the reading portion of the original 8 or the like is irradiated as much as possible.
1'can be reduced.

Next, in FIG. 7, 1 is a frame, 2 is an LED chip, 3 is a glass plate, 5 is a rod lens array, 6 is a circuit board, 7 is a light receiving sensor, 8 is a manuscript, and the like.
Reference numeral 4 denotes a support member that supports the rod lens array 5, supports two side surfaces of the rod lens array 5 between the wall surface of the support member 14 and the wall surface of the frame 1, and further supports the lower surface of the support member 14 and the glass plate 3. And the upper side surface of the support 14 is joined to the circuit board 6.

As shown in FIG. 7, in the third conventional example, since the opening 4 of the frame 1 shown in FIG. 4 is eliminated, irregular reflection on the side surface of the opening 4 is eliminated. Also, the rod lens array 5
One of the two side surfaces of the rod 1 is supported by the wall surface of the frame 1 and the other is supported by the wall surface of the support body 14, so that the side surface of the rod lens array 5 is covered by the wall surface of the support body 14.
The light of the LED chip 2 does not enter directly from the side surface of the rod lens array 5.

[0010]

However, in the structure of the conventional contact type image sensor, in the first conventional example, it is difficult to align the rod lens array 5 arranged in the opening 4 inside the frame 1, and variations occur. Prone to occur,
Stray light 11 'is generated to reduce the S / N ratio. Further, in the second conventional example, although the stray light 11 'itself can be improved, the structure itself of the frame 1 is complicated, and the processing cost of the frame 1 becomes high and the cost becomes expensive. Further, in the third conventional example, the rod lens array 5 is supported by the wall surface of the frame 1 and the wall surface of the support body 14, but positioning such as optical axis adjustment of the rod lens array 5 and the light receiving sensor 7 at the time of assembly is performed. Difficult, and the frame 1 has weak mechanical strength 2
Since it has a piece structure, it has a problem that the optical axis is easily displaced when incorporated in a facsimile or the like.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a contact-type image sensor which facilitates the positioning of the rod lens array, eliminates stray light, and improves the S / N ratio. .

[0012]

In order to achieve this object, a contact type image sensor of the present invention has a plurality of LED chips for irradiating an original or the like and a substrate on which the LED chips are mounted, mounted and irradiated from the LED chips. A holding frame having an optical path for passing the reflected light, a frame formed with a concave portion for housing the holding frame and a rod lens array for converging the light rays reflected by the original, and the converging with the rod lens array. The holding frame is provided with a light receiving sensor for receiving the generated light beam, and the holding frame is formed with a positioning portion for positioning the frame and the rod lens between the wall surface of the concave portion and the wall surface of the holding frame by the holding frame. It is characterized by sandwiching the array.

Further, the contact image sensor of the present invention is
It is characterized in that the optical path portion is provided with a slope portion that intersects with a surface of a document or the like at an acute angle.

The contact image sensor of the present invention is
It is characterized in that the positioning portion is provided at the tip of the comb teeth of the comb-shaped mounting portion on which the substrate is mounted.

Further, the contact type image sensor of the present invention is
It is characterized in that a slope is formed in the recess substantially parallel to the slope.

Further, the contact image sensor of the present invention is
The frame is characterized in that an opening is formed on the bottom surface of the recess.

[0017]

The contact type image sensor of the present invention has a positioning portion for positioning between the frame and the holding frame,
Since the rod lens array is sandwiched between the wall surface of the recess and the wall surface of the holding frame by the holding frame, the optical axis adjustment of the rod lens array and the positioning and fixing of the rod lens array are facilitated.

Further, the contact image sensor of the present invention is
Since the optical path has an inclined surface that intersects with the surface of the original at an acute angle, the emitted light rays are guided to the surface of the original while being diffusely reflected, and a substantially uniform light beam is emitted near the reading section of the original. You can

Further, the contact type image sensor of the present invention is
Since the positioning portion is provided at the tips of the comb teeth of the comb-shaped mounting portion on which the substrate is mounted, the optical path is formed and the mechanical strength is not reduced.

The contact image sensor of the present invention is
Since the inclined portion is formed in the concave portion of the frame as a substantially parallel inclined surface, the irradiated light beam is guided to the surface of the manuscript or the like while being irregularly reflected, and a substantially uniform light beam can be irradiated near the reading part of the manuscript or the like.

Further, the contact image sensor of the present invention is
Since the opening is formed at the bottom of the recess in the frame, stray light is not generated at the opening even if the rod lens array is displaced.

[0022]

An embodiment of the present invention will be described below with reference to the drawings. 1 is a partially cutaway perspective view of a contact image sensor according to an embodiment of the present invention, and FIG. 2 is a sectional view of a contact image sensor according to an embodiment of the present invention.
FIG. 3 is a perspective view of a holding frame of the contact image sensor according to the embodiment of the present invention. In FIGS. 1, 2 and 3, reference numeral 15 is a frame made of aluminum or the like, and an opening 16 is provided below the inside of the frame 15 and penetrates therethrough.
A recess 17 provided on the upper side of the opening 16 is provided, and an engaging portion 18 for performing positioning with a holding frame 20 described later is provided above the recess 17. The opening 16 is formed on the bottom surface of the recess 17.

Reference numeral 19 is a rod lens array that is housed in the recess 17 of the opening 16 and focuses the light rays reflected by the surface of the original 33 or the like through the glass plate 30 described later. Reference numeral 20 is a holding frame that is housed in the recess 17 and is made of polycarbonate or the like. is there. A holding wall surface 21 for holding the rod lens array 19 and a substrate 28 on which an LED chip 29, which will be described later, is mounted are mounted on the holding frame 20, and a mounting portion 22 is formed in a comb shape by the groove 25. A positioning part 23 for positioning between the frame 15 and the holding frame 20 provided at the tips of the comb teeth of the mounting part 22, a surface 24 for supporting the mounting part 22, and an inclined surface provided below the groove 25. The part 26 and the holding frame 20 to the frame 15
It has a support surface 27 that is placed on the bottom surface of the recess 17.
The groove 25 and the slope portion 26 form an optical path portion of the light beam emitted from the LED chip 29. The optical path is the LED chip 2
The light beam emitted from 9 passes through to the opening 16.

By the way, the rod lens array 19 is sandwiched between the wall surfaces of the recess 17 of the frame 15 and the sandwiching wall surface 21 of the holding frame 20 by the holding frame 20 on both sides thereof. That is, the holding frame 20 is positioned by bringing the locking portion 18 and the positioning portion 23 of the frame 15 into contact with each other. By this contact, the rod lens array 19 can obtain a pressing force from the holding frame 20. The rod lens array 19 is clamped and fixed in the recess 17 by the holding frame 20.

Reference numeral 28 denotes a substrate which is mounted on the mounting portion 22 of the holding frame 20 and the mounting surface of the frame 15 so as to partially extend over it. An LED chip, 30 is a glass plate disposed in a recess under the frame 15 on which the light beam emitted from the LED chip 29 is incident, and a document 33 or the like is brought into contact with the glass plate, 31 is the frame 1
5. A circuit board which is arranged in the upper recess and which converts a photocurrent generated corresponding to the original 33 into a voltage by a light receiving sensor 32, which will be described later, and 32 is provided on the lower surface of the circuit board 31 to focus the rod lens array 19. A light receiving sensor for receiving a light beam, and 33 is a document or the like which is brought into contact with the glass plate 30 and irradiated.

The operation of the contact type image sensor constructed as above will be described with reference to FIG. L
Light rays emitted from the ED chip 29 (indicated by a dotted arrow)
However, the light passes through the optical path portion of the holding frame 20 and is incident on the upper surface of the glass plate 30 in an oblique light state. At that time, the holding frame 20 is LE
The D chip 29 and the light receiving sensor 32 are optically separated from each other, and the light beam emitted by the LED chip 29 does not directly enter the light receiving sensor 32. Further, the light beam emitted from the LED chip 29 is diffusely reflected between the optical path portion of the holding frame 20 and the slope of the recess 17 of the frame 15, and enters the glass plate 30 with a uniform illuminance distribution. . The slope of the recess 17 is formed substantially parallel to the slope 26 of the optical path.

The light rays incident on the glass plate 30 are refracted and reach the lower surface. On the other hand, on the lower surface of the glass plate 30, there is a document 33 or the like that is conveyed so as to be in close contact with the glass plate 30. Reflects light rays toward the top surface.
The reflected light beam is focused by the rod lens array 19 provided above the glass plate 30. Then, the focused light beam is received by the light receiving sensor 32, and a current corresponding to the received light amount is output in time series, converted into a voltage by the circuit board 31, amplified and output.

As described above, in the structure shown in the embodiment of the present invention, the optical axis of the rod lens array 19 for focusing the light rays reflected on the lower surface of the glass plate 30 is positioned by the frame 15 on both side surfaces of the rod lens array 19. It is carried out by sandwiching it between the wall surface of the concave portion 17 and the holding wall surface 21 of the holding frame 20, and making the locking portion 18 of the frame 15 and the positioning portion 23 of the holding frame 20 face each other. The rod lens array 19 does not shift left and right and up and down, and the optical axis can be adjusted easily and surely. And the rod lens array 1
When the 9 and the holding frame 20 are housed in the recess 17, the dimensional relationship of the recess 17 is such that the rod lens array 19 and the holding frame 20 can obtain a pressing force from the recess 17. It is made slightly smaller than the width of 20. Therefore, the rod lens array 19 is held by the holding frame 20. Further, even with two pieces, the mechanical strength is increased because of the concave structure.

In this manner, the optical axis shift of the rod lens array 19 is eliminated, and the holding frame 20 is arranged so that the light beam emitted from the LED chip 29 does not directly enter the light receiving sensor 32.
In addition, since the aperture 16 is provided between the rod lens array 19 and the original 33, the generation of stray light is eliminated and the S / N ratio can be improved.

Further, the recess for disposing the glass plate 30 of the frame 15 is formed not by boring but by processing the outer surface, and the rod lens array 1 is formed on the upper side of the opening 16 based on this recess.
The concave portion 17 for accommodating the holding frame 20 and the holding frame 20 and the recess for arranging the circuit board 31 are formed by external surface processing at predetermined heights, and the holding frame 20 can be easily manufactured at low cost with good processing accuracy. Moreover, since each processing precision is good, the assembly precision of the contact image sensor is improved,
It can be easily assembled without the optical axis shifting.

[0031]

As described above, in the contact image sensor of the present invention, the positioning portion for positioning the frame and the holding frame is formed, and the holding frame is provided between the wall surface of the recess and the wall surface of the holding frame. Since I sandwiched the rod lens array,
The optical axes of the rod lens array and the light receiving sensor can be easily adjusted and the rod lens array can be easily positioned, and the rod lens array can be assembled easily and accurately.

Further, in the contact type image sensor of the present invention, since the optical path portion is provided with the slope portion which intersects the surface of the original document or the like at an acute angle, the irradiated light rays are guided to the surface of the original document or the like while being diffusely reflected. Since a uniform light beam is applied to the vicinity of the reading portion of a document or the like, stray light can be eliminated and the S / N ratio can be improved.

Further, the contact image sensor of the present invention is
Since the positioning portion is provided at the tips of the comb teeth of the comb-shaped mounting portion on which the substrate is mounted, even two pieces can be easily and accurately assembled and the mechanical strength is increased.

Further, the contact type image sensor of the present invention is
Since the inclined surface is formed in the concave portion of the frame as a substantially parallel inclined surface, the irradiated light is diffused and guided to the surface of the manuscript or the like, and a substantially uniform light is irradiated near the reading part of the manuscript or the like, so stray light is eliminated. The S / N ratio can be improved.

Further, the contact image sensor of the present invention is
Since the opening is formed in the bottom surface of the recess in the frame, stray light is not generated from the opening even if the rod lens array is displaced.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a contact image sensor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a contact image sensor according to an embodiment of the present invention.

FIG. 3 is a perspective view of a holding frame of the contact image sensor according to the embodiment of the present invention.

FIG. 4 is a sectional view of a contact type image sensor of a first conventional example.

FIG. 5 is a diagram illustrating stray light of a conventional image sensor.

FIG. 6 is a sectional view of a contact image sensor of a second conventional example.

FIG. 7 is a sectional view of a contact image sensor of a third conventional example.

[Explanation of symbols]

 15 frame 16 opening 17 recessed portion 18 locking portion 19 rod lens array 20 holding frame 21 sandwiching wall surface 22 mounting portion 23 positioning portion 24 surface 25 groove 26 slant surface portion 27 support surface 28 substrate 29 LED chip 30 glass plate 31 circuit board 32 Light receiving sensor 33 Original

Claims (5)

[Claims] 1. A plurality of LED chips for irradiating a document or the like,
A holding frame provided with a substrate on which the LED chip is mounted and having an optical path portion for passing the light emitted from the LED chip, and a rod lens for accommodating the holding frame and focusing light rays reflected by a document or the like. A positioning unit for positioning the frame and the holding frame in the holding frame, the frame having a recess for accommodating the array, and a light receiving sensor for receiving the light beam focused by the rod lens array. And the rod lens array is sandwiched between the wall surface of the recess and the wall surface of the holding frame by the holding frame. 2. The contact type image sensor according to claim 1, wherein the optical path portion has a slope portion which intersects a surface of a document or the like at an acute angle. 3. The contact type image sensor according to claim 1, wherein the positioning portion is provided at a tip of a comb tooth of a comb tooth-shaped mounting portion on which the substrate is mounted. 4. The contact type image sensor according to claim 2, wherein an inclined surface which is substantially parallel to the inclined surface portion is formed in the concave portion. 5. The contact image sensor according to claim 1, wherein an opening is formed in the bottom surface of the recess in the frame.