JPS6364471A - Image sensor - Google Patents

Abstract

PURPOSE:To attain the read adjustment of an accurate picture with a simple method by setting a lighting device, an image forming lens and a photodetector to an optically optimum position and integrating them. CONSTITUTION:An original 1 is carried from the arrow B to the B' by driving a roller 2 in the direction of arrow C. Picture information of the side A of the original 1 is to be read in a way that a radiated light from an LED chip 10e is converged and radiated by a rod lens 10a, the reflected light is made incident on the light receiving section of a sensor 14 via an unmagnification lens 13, where the light is subjected to photoelectric conversion. Then the plane of the lens 13 intersected orthogonally with an optical axis is used as a split face as the structure. Then the position of the light receiving line of the sensor 14 is adjustable at the plane intersected orthogonally with the optical axis, and the lighting device 10, the lens 13 and the sensor 14 are coupled to integrated them at an optically optimum position.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a document reading device that reads image information of a document.
In particular, the present invention relates to a so-called contact type image sensor, which is a 1-magnification type image sensor that does not have a reduction optical system and is used near an original.

[Prior Art 1 A conventional device of this type was composed of the following elements. The first is a light source for illuminating the document, the second is a 1-magnification I-nons that images the reflected light from the document onto the sensor light receiving surface, and the third is a light source for illuminating the document.
It is a sensor that converts photoelectrically into

FIG. 6 shows a conceptual diagram of a conventional contact type image sensor (hereinafter simply referred to as C5). In the figure, a document 41 is conveyed in the direction of arrow A. 42 is an LED array having an illumination length equivalent to the width of the paper in a direction perpendicular to the drawing. 43
is the I-nons array. 44 is an image sensor that reads image information.

FIG. 7 is a sectional view of an example of a conventional example.

In the figure, 51 is a document to be read, and 52a is aluminum.

This is an LED chip bonded onto a substrate 52b made of glass or epoxy. 52cij: This is a rod-shaped lens that focuses the amount of light. 52d is lens 52c
53 is a lens array, 54 is a sensor, 558:105 The entire structure is usually made of aluminum extrusion, which has a high heat dissipation effect.

Reference numeral 56 denotes a document kite for holding the document 51 between it and the platen roller 58 and transporting the document in the direction of arrow (A);
7 is a plate that moves the lens array in the directions of arrows C and D (=J), and 58 is a platen roller that rotates in the direction of arrow B. TC is an i7E Ill between the document and the sensor.

FIG. 8 is a perspective view of the conventional example shown in FIG. 7.

5! La, 5! lb is fixed to the frame 55 from both sides by a side plate on the side of C8. Reference numeral 60a denotes an adjustment screw for finely adjusting the position of the lens array in the E direction by pushing the I/lens array 53 in the direction of the arrow E and using the suppressing force of the plate spring 57. There is also a similar gap on the side plate 59b, which is shown only on the front side in the figure.

In the configuration described above, the operation of the CS will be explained.

The image information surface of the original 51 is illuminated at the reading position by condensing the light emitted from the LED chip with a rod-shaped lens. The reflected light from the illuminated original is focused on the sensor light receiving area using a lens array,
The sensor performs photoelectric conversion and reads image information. Here-I
The IQ-based component attachment will be explained in relation to the CS output performance. C5 output is uniform and ht
In order to obtain a high TF, the following are required: 1) uniform illumination of the reading position (line); 2) imaging of document image information with a high MTF.

Usually, because the above conditions were not met, each component had to be highly accurate, resulting in a high-cost C5.

The parts with high accuracy will be explained below.

In FIG. 7, the LED is screwed onto the F side. Tofu, as a fitting stopper using screws for the hen board 52b,
It achieves high accuracy in parts removal.

Here, the light amount distribution of illumination by the LED array will be explained. FIG. 9(A) is a perspective view of the LED array.

Figure 9(B) shows the light intensity distribution at a distance corresponding to the document surface from the LED and 1, and on a plane parallel to the ED ρ board.
This is a dimensional representation. This is X! Ii [ll is the longitudinal direction of the LED (reading line position), YφIll [
j: Axis perpendicular to the x-axis and parallel to the j2 substrate; I indicates the amount of light at each point on the XY plane. 91 is an illuminance distribution curve on a plane orthogonal to the X axis.

As can be seen from FIG. 9(B), the amount of light is maximum at Y-O. Further, 1. The E0 chips 52a are usually arranged at a pitch of several mm in the X direction, and the amount of light has a wave-like ripple.

FIGS. 10(8) and 10(B) are cross-sectional views taken along a plane perpendicular to the X-axis in FIG. 9. Here i;t: 1.
, Removal of parts that cause unevenness in the amount of light in the lighting
Let's talk about accuracy. 10(8) shows a state in which the center of the lens 52c is deviated from the ideal position by Δ. At this time, the light condensing position shifts from 53a to 531].

FIG. 10(B) shows that when the position of the LED deep 52a deviates from the ideal position by Δ3 i-1, the light condensing position shifts by Δ4.

FIG. 11 is a diagram showing how much the illuminance at the reading position changes when the condensing position shifts by Δ2 or 4-1.

In Figure 11, Ql, ! 12 is the illuminance D on a plane perpendicular to the X-axis as shown in FIG. 92 is the first
As shown in Figure 0 (8), the illuminance distribution is shown when there is a deviation of Δ2. By the way, the illuminance of one LED lamp is usually 6J or about 1000 fLx. If the reading position is as shown in Figure 10 (A), the illuminance at the reading position will deteriorate to +27 I, Therefore, the illuminance increases rapidly near the optical axis of the illumination system as shown in Figure 11.Is it possible to obtain a width of 1 mm in the Y direction with 90% of the output of 11? be.

Therefore, in order to ensure uniformity of illuminance on the document surface, it is necessary to improve the accuracy of the following items.

l) Lens position (Figure 10 (A)), 2) LE
D chip position (Figure 10 (B)), 3) Distance between lens and chip 1! tll HI, 4) Distance H2 between the chip and the document, 5) Mounting position of the LED i board (relative position to the reading position), 11.2) of which are described above. Here, a case will be described in which the above-mentioned positional relationship is shifted at both ends of the LED, but the intermediate portion is linearly stable.

Regarding 2), since the chip is usually bonded by a robot, the accuracy is about 50 μm, and the precision of the chip in FIG. 1O (B) is also about 0.1 to 0.2 mm.

Regarding 1), △1 in Figure 10 (8) is generally ±0.3
It is about mm, and Δ2 is approximately ±1 to ±2 mm.

Regarding 3) and 4), the accuracy is at the limit of about ±0.2 mm, respectively, and causes a variation in the amount of light of about ±15%.

5) is the mounting accuracy of the 11 board 52b to the F side in FIG. 7, which is about ±0.2 mm or a limit.

For the above reasons, the two-dot chain line or 3 in Figure 17 was later
As shown by the dashed dotted line, the illuminance on the document surface reading position line is uneven. In this way, if the illuminance at the reading position is not uniform, the output from the sensor will be uneven, resulting in smudges on the read image and poor resolution of halftone originals. .

Until now, the following methods have been used to eliminate these drawbacks.

1) Rotate the 1/lens or adjust the fixed position of the lens.

2) 1. , ED Aρ substrate is finely adjusted and positioned.

3) Increase the accuracy of each part and publish a uniform publication by combining each part without having to worry about selection.

In both cases, the equipment was complex, the number of man-hours was high, and the cost was high. Especially 1. The method of adjusting the position of the entire ED must be done by looking at the illuminance distribution on a two-dimensional plane, which requires an excessive number of man-hours.

FIGS. 12 to 15 are diagrams explaining a lens array (hereinafter referred to as S, 8).

FIG. 12 shows the structure of SL83, and shows 17 rod-shaped lenses 61 arranged in two rows in a staggered manner. 62 is a resin, and 63 is a side plate.

FIG. 13 is a diagram showing the imaging state of the SLA, and shows that an erect image of equal magnification can be obtained by overlapping the imaging of each rod-shaped lens 61. 64 is a document surface, 65 is an image surface, and 66 is an illuminance distribution.

FIG. 14 is a diagram showing the illuminance distribution on the image plane when uniformly diffused light is incident on the SLA, and each rod-shaped lens 61 shows a mountain-like distribution 66 with its peak at the central axis of the l-nons. On the image plane, multiple mountain-like overlapping illuminance distributions 67
I can see that it shows.

FIG. 15 is a three-dimensional diagram showing the phenomenon described above.

FIG. 16 shows the illuminance distribution on the X-direction line when the imaging side is Δy from the optical axis. As can be seen from the figure, it can be seen that a ripple of J: is generated in each rod lens.

゛ Also, a line with uniform illuminance on the document surface and SLA
If the line , the line of the light receiving part of the sensor, and the line SI are misaligned, the illuminance on the sensor surface may become uneven as shown by the two-dot chain line or the three-dot chain line in Fig. 17. There is. Below S1. Deterioration of resolution depending on the position of A will be described below.

FIGS. 18(A), 18(B), and 18(C) show the relationship between the position of the SLA and the MTF with respect to the subject plane and the image plane, respectively. Each of the four tree lines in the graph on the right is t
l, 2.

M of L Temple who advertised 4.6 and 8LP/mm diat.
This shows TF. In the figure, TCi:l represents the distance between the original and the sensor. (a), (b), (C
), assuming that the upper surface of the TC is the original position and the lower surface is the sensor position, the MTF is highest when Sl, A are placed in the middle of the TC.

FIG. 18(A) shows the change in MTF when the sensor and SLA are fixed and the position of the document varies. In the same figure (B), when the document and sensor are uncut or constant, Sl,
It shows the MTF that changes depending on where A is.

Figure (C) shows the case where Sl and A are fixed and the distance between the document and the sensor changes. In particular, SLA is always in the middle of the document sensor (that is, T (:/2) is always protected. ) indicates the case.

Generally, the SLA and sensor are held together as a sensor unit, so the TC/2 is often fixed.

TC has a sensor unit on the document backup roller]
Dimensions are determined mechanically by pressing.

If you want to, you can say the following.

FIG. 18 (8) shows the allowable amount of variation in the transported documents. Figure (B) shows the required positional accuracy for Sl within the sensor unit. Figure (C) shows the sensor installation of the sensor unit 1- and the distance tolerance of the backup roller.

As can be seen from FIG. 18 (8), when the SLA position is shifted from the center (1/2 TC position) with respect to the total optical path length TC, the MTF deteriorates significantly.

- In order to solve the problem mentioned above, conventionally, in Fig. 7, the structure is such that St and 8 are brought into contact with the 6th surface, and the sensor is fixed to the frame 55 with precision, so that it is parallel to the reading line. It was common practice to increase the accuracy of parts to improve performance. However, because of this, parts become expensive! :l: cs The overall cost increased, and it was not possible to provide an inexpensive C8.

[Problems to be Solved by the Invention] It is an object of the present invention to eliminate the above-mentioned conventional drawbacks, and to provide an inexpensive image sensor that is capable of accurate adjustment using a simple method.

[Means for Solving Problem 1] In order to achieve the above object, the image sensor of the present invention includes an illumination means for illuminating the image information surface of the document, and a method for converting the reflected light on the document surface by the illumination means at the same magnification. an image forming means for imaging, a light receiving element located on an image plane ahead of Q1 and photoelectrically converting the [n] light and reading image information, a structure that integrally holds the illumination means and the image forming means, and the light receiving element. The device has a structure in which the illumination means, the imaging means, and the light receiving element are separated, and the part orthogonal to the optical axis of the imaging means is divided as a dividing plane. The position of the light-receiving line of the light-receiving element can be adjusted in a plane perpendicular to the optical axis, and the illumination means and imaging means and the light-receiving element can be combined into an integrated structure at an optically optimum position. It is characterized by

[Function] According to the present invention, it is possible to read a document at an optimal position while eliminating the influence of ripples on Sl. In addition, the adjustment of the entire CS unit can be done by adjusting the sensor position or adjusting the SLA position. Therefore, the unit assembly and adjustment process can be shortened and a very inexpensive unit can be provided.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention.

In particular, a type of document reading device in which a document is conveyed in a U-turn from the bottom to the top, and a sensor of equal size as a light receiving element will be described.

In FIG. 1, numeral 1 is a document, and image information to be read is located on the arrow A side. Reference numeral 2 denotes a drive roller for conveying the original in the direction of arrow B, which is rotated in the direction of arrow C by a drive source (not shown) and then reads the image information of the original 1. 3 is the structural frame of the device, 3a and 3b are the guides for the roller 2, 3a is the upper kite, and 3b is the lower guy. 4 is an ejection guide for guiding the document 1 out of the device, 5 is an upper cover of the device, and 5a is a cover that also serves as a guide for the ejection section, which can be rotated in the direction of arrow C7j, and can be repaired in the event of a jam. It is structured like this.

6 is the bottom cover of the device. Reference numeral 7 designates a pressing kite which exerts a conveying force on the original 1 by holding the original 1 between the roller 2 and a pressing means to be described later. Reference numeral 8 denotes a structure of a reading unit to which an illumination means 9, a same-magnification lens means, a sensor, etc., which will be described later, are fixed to the main body. The structure 8 is made of aluminum drawn material, aluminum die-cast material, or old rice grains such as resin. Reference numeral 9 denotes a hole for the center of rotation which is fixedly fixed in the structure (hereinafter referred to as holder) 8, and the boulder 8 has a hole for the center of rotation between the main body and the center of rotation 9.
It is pivoted so that it can rotate from both sides. 10 is a lighting means. 1] 1: I document reading position, 12 is the light receiving line of the second light receiving element. Reference numeral 13 denotes a 1-magnification lens for guiding the reflected light from the document reading position to the light receiving position 12, and 14 a sensor having a photoelectric light receiving section at the light receiving position 12. 20 is an actuator that rotates when the original 1 is inserted; 21 is a detector that detects the rotation of the original 1; a mounting plate that fixes the light receiving element 14 ; 1 - A board on which one drive circuit is mounted is connected to a system controller (not shown), and the light receiving element is driven by a manual signal from the system controller, and the optical output signal of the light receiving element 14 is transmitted to the system controller. It is output by the signal processor Jjp, l, as shown in Figure 32.
15; l This is a pressing means for pressing the reading unit 1 to the roller 2 side. 34 is a connector that electrically connects the light receiving element 14 and the drive circuit of the board 310.

In the document reading apparatus of the embodiment having the configuration described above, the document 1 is conveyed from the direction of the arrow B to the direction of the arrow B' by rotating the roller 2 in the direction of the arrow C. Manuscript 177
) The image information on the A side is generated by the light emitted from the LT:D depth 10e being collected by the rod-shaped lens LOA, and the reflected light is reflected by the light receiving part of the sensor 14 through the lens 13, and the sensor 14 generates a photoelectric signal. It becomes possible to read the converted image information.

FIG. 2 is a perspective view showing more specifically the structure of the unit 1- of the reading section shown in FIG. 1, and FIG. 3 is a partial perspective view of the CS unit.

At this point fg, the document 1 is inserted from the direction of the arrow B and is then U-turned in the direction of B' and taken out 141. The configuration not explained in FIG. 1 will be explained below. The symbols used are those in Figure 1 and Unified Zap 1.

2a is a pulley on one side of the roller 2, and 2b is a heald that transmits driving force from a drive system (not shown). 7a and 7b are set screws for fixing the pressing guide 7 to the holder 8;
8a to 8c are set screws for fixing the lens to the halter 8 from a direction perpendicular to the optical axis of the imaging lens 13; 8d;
8e is a hole made in the porter 8 so that the side surface of the lens 13 can be touched from the side shown in FIG.

Using the holes 8d and 8e, it is possible to adjust the position of the lens 13 in the optical axis direction using a needle-like protrusion of a jig (not shown) or the like. 8f and 8f' are shaft supporting holes provided on the side surface of the holder 8, 8f is a circular hole and 8f' is an elongated hole. 8g and 8h are taps provided at both ends of the holder 8, and are connected to the light receiving element mounting plate 3 explained in FIG.
This is to fix 0.

9a, 9bij From both sides of the device, pass through the taps provided on the frame 3 and insert the above-mentioned Holter into the bottle at the tip.
The halter 8 is pivotally supported so as to be rotatable in the direction of the arrow M about this pin as a center of rotation.

10 is the illumination means as mentioned above, and lOe is the substrate 1.
A small rectangular light-emitting LED depth is bonded on 0b, and l[la is the light emitting flux of the chip, which is focused on the reading position 1.
A rod-shaped lens for illuminating the original in 1, IOd is L
At both ends of the ED array, the rod-shaped lenses 10a are used as LEDs.
Lens house for fixing to substrate 10b, IOc is L
This is an external resistor installed to limit and adjust the ED current value, and is soldered to the ED board.

30 is a light receiving element mounting plate, 30a and 30b are porter 8
The mounting plate 30 can be fixed by adjusting the position of the mounting plate 30 with respect to the halter 8 by making a hole through which a stop hiss 33 for fixing is passed. 30c and 30d are light receiving elements 1
Cut-and-raised portion for positioning by abutting the crow end surface of 4, 3[1e, 30f, 30g, 30
h is also Enhos for hitting the end face, 3Q
i, 3 (lj is the drive circuit board 31 (hereinafter referred to as PεB)
A fixed surface is provided with a tap or tap to fix it. 30k.

30u, 30m, and 30n are claws for catching the PCB to prevent it from floating; 30o and 30p are claws for catching springs as pressing means; 31a and 31b are for holding the PCB (=fixing it to the J board 30). This is a set screw for 32a.

Reference numeral 32b denotes pressing means, and the same ones located at two locations on the left and right sides are not shown.

34a and 34b are press-contact type connectors, which in this case connect the sensor and the PCB at two locations on the left and right.

In FIG. 3, +4a is a glass plate of Heas, and a pattern is formed on the upper surface of the figure by vapor deposition.

14b is a sensor chip cut out from a wafer, a part of the sensor is formed on the top surface, and the color space 14a is
is fixed with transparent adhesive. Reference numeral 14c denotes a mold frame made of silicone rubber or the like, which is adhesively fixed to the glass base 14a and serves to position the connectors 34a and 34b and to prevent the molding F material (silicon rubber) from flowing out. Eyes d and 14e are the gold plating pattern of the glass base 14aJ1, and the upper part of this is the molding I.
-The frame is hollowed out. The connector fits into this part and is positioned. +4f is a bonding wire that connects the sensor chip eye and the pattern of the color space +4a, and 14g is an elastic member such as silicone rubber that is filled over the sensor depth and protects the bonding.

31c and 31d are fitted with round holes and slotted holes 31a and 31b drilled in the PCII 31, respectively, and the PCB is positioned by tying the screws together. In Fig. 3, the screws and screw holes are used to fit together, but it is also possible to position the screws and the screw holes with the other external parts and the claws on the plate, so that the screw holes and the screw holes are in a similar relationship. 31e and 31f are mounting plates 3, respectively.
This is a notch that catches on the catching part of 0e and 30 and prevents the PCB from floating toward the -1- side.

31g, 3]hLj Soil, 3On, 30m It catches on the nail and prevents it from floating in the same way.

For each connector, the screw stopper and two hooks prevent the connector from floating in the negative direction in three directions,
Ensures the connection of the connector.

31i, 3]j is a pattern on the back side of the PCB and is located at position i7, same as sensor patterns 14e and 14d.
The CB and the sensor are electrically coupled.

The present invention incorporates SLA into the sensor unit to
When fixing A, the structure is such that it can be fixed by adjusting the SLA position to TC/2 so that MTF is at its maximum. Further, in the present invention, the guide plate 7 is
Since the kite board 7 is fixed by positioning (threaded fit) at the holder 8, when adjusting this, the kite board 7 must be finely adjusted relative to the holder 8 to ensure a good fixation.

As explained above, CS (contact image sensor)
) to hold the illumination means and image forming means together, and also to hold the light receiving element and its drive circuit, etc., together, and when the two are connected, By having a structure that allows fine adjustment of the coupling position in the ① direction and fine adjustment of the coupling position in the 0 rotation direction, it has become possible to obtain the following effects.

(1) If the illumination light source is not adjusted as described in the description of the conventional example, the illuminance on the document surface will be as indicated by the two-dot chain line or the three-dot chain line in FIG. Assuming that the sensor is reading the reading position line, the output waveform of the sensor will be similar to that in FIG. 17. Therefore, if the light receiving section side is rotated in the direction of the arrow @ in FIG. 2, the sensor output waveform can be flattened as shown in FIG. 4.

(2) As mentioned above in the explanation of St□A, the scene distribution transmitted and imaged through Sl,8 is as shown in FIG. In particular, if the illuminance distribution on the original surface is uniform and diffuse, the sensor output equivalent to the transmitted light amount distribution will be as shown in FIG.

Here, the output with high output and ripple (curve A) is Sl
, on the optical axis line of A.

By the way, by relatively moving the position of the light-receiving element in the direction of the arrow ``J'' shown in Figure 2 at 51 and 8, the sensor output can be maximized as shown by curve B in Figure 5. Although it will be a little lower than the output, it is possible to create a flat shape with no ripple to the SL.

(3) In (1) and (7), the results were described separately for the illumination means and the imaging means, but in the present invention, the illumination means and the imaging means are held integrally, and the beams are integrated. In order to adjust the sensor line with respect to the held structure, in order to select and measure the positional relationship that has the highest output and flatness with respect to the imaged scene distribution on the sensor surface, which is a combination of illumination means and imaging means, The effects described in (1) and (2) can be obtained simultaneously with a single adjustment.

(4) Also, by moving the sensor in the direction of the dashed arrow 0B in Figure 2, the reading start position of the sensor, which is the document width direction (+scanning direction) Pronation is about accurately adjusting the positional relationship of the sloping reading width.

[Effect of the invention] According to the present invention, l'1. i:1' SL, except for the influence of ripples of A, read with the optimal device 1st t7, SL
It is also possible to arrange the 8-to-8 pieces without using two rows of FP4-shaped quibs. , - Cosplay using inexpensive single-row linear disks! - is cheap 3, J, ta f: Adjustment of the whole knit to s- is 1 unit → Y-'s 1 position and 1 round is SL
A's A8 1 U" put out (bottle 1 - put out) GJ te -
4-M. Therefore, it is possible to shorten the length of the I-knit adjustment balls fl and l, and to provide a very inexpensive I-knit.

[Brief explanation of the drawing]

Fig. 1 Cr1 An example of an integrated reading device according to the present invention h1ζ
tJi side view, Fig. 2 (perspective view of the reading setup incorporating the J wood I and 4 light embodiments, Fig. 3 includes the embodiment of the present invention), : of the reading device (:
Partial sound 1 view of the S unit, Figures 4 and 5 are diagrams showing the output of the old sensor, Figure 6 is a conceptual diagram of the conventional CS and T-T, and Figure 7 is a diagram showing the output of the old sensor. Cross-sectional view of conventional CSS Units]・Figure 8 C1j Conventional CS
A perspective view of the unit 1-, FIG. 9 (Δ) is a perspective view of 11・D, FIG.
), (B) is a cross-sectional view of Lu1l, and Figure 11 is 1F+
Fig. 12 is a perspective view showing the configuration of 5l-A, Fig. 13 is an explanatory diagram of the state of imaging, Fig. 14 is an SLA
An explanatory diagram of the optical velocity of the imaging plane, Figure 7jfJ15 is 51. FIG. 16 is a perspective view of the direction of light quantity Vji of the 8 and its imaging plane. A 11 explanatory diagram and FIG. 17 are for A light amount. , FD light h1) 1 according to the old (2 sensor - output diagram, Figure 18 (8), (II), (C) is 4
1soJ'1. FIG. 3 is an explanatory diagram showing the relationship between the Q correction to the SL and the resolution. 1... Manuscript, 8... Polter, lO... Illumination means, 10a... Rod-shaped lens, 10e=41:, D chip, 13... Equivalent 1 nons, 14...) Funcer , 4 30...Number of light receiving elements - 1 plate. Figure 15

Claims (1)

[Claims] An illumination means for illuminating the image information surface of the document; an imaging means for forming an image of the reflected light from the document surface by the illumination means at the same magnification; It has a light receiving element for reading information, a structure for integrally holding the illuminating means and the imaging means, and a means for integrally coupling the light receiving element and a drive circuit for the element, The imaging means and the light-receiving element are separated from each other, and a plane perpendicular to the optical axis of the imaging means is used as a dividing plane, and the position of the light-receiving line of the light-receiving element is adjusted on the plane orthogonal to the optical axis. An image sensor characterized in that the illuminating means, the imaging means, and the light receiving element can be combined into an integral structure at an optically optimum position.