JP2007208402A - Image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor capable of reading a highly accurate image with uniformized image quality by positioning a relative position between each of light receiving elements and each of lenses configuring a lens array to thereby reduce dispersion in images among the respective compact image sensors (CIS) due to optical coupling between the lens array and the light receiving elements. <P>SOLUTION: The image sensor includes: a light source for emitting light to an original; the lens array where a plurality of the lenses are arranged in a main scanning direction of the original and which converges light reflected in or transmitted through the original; a sensor substrate on which the sensor elements (light receiving elements) for receiving the light converged by the lens array are arranged linearly and reference positional marks are provided on the extended line of the arrangement; a support member formed with a through-hole the surrounding of which is surrounded in accordance with the sensor elements and for supporting the lens array by mounting the lens array to the through-hole; and positioning members provided in the sensor substrate in matching with the reference positional marks and positioning the support members. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an image sensor (image reading device) used in a facsimile, an image scanner, a copying machine, a financial terminal device, and the like, and more particularly, to a contact image sensor as an input device for reading a document.

A contact image sensor (hereinafter sometimes referred to as CIS) is a light source such as an LED light source, a fluorescent lamp, or a xenon tube that emits light, and a rod lens array that converges light from a light source reflected or transmitted by a document. And a sensor unit including a photoelectric conversion element that converts light converged by a rod lens array into a voltage. The sensor elements of the sensor unit are arranged in a linear array over the width direction (main scanning direction) of the read image, and the CIS functions as a one-dimensional line sensor.

The principle of reading images by CIS will be described by taking a monochrome image as an example. Utilizing the characteristic that the amount of light reflected differs depending on the shade of the image, the light from the light source reflected or transmitted by the original (including black and white originals, banknotes, securities, etc.) is reflected on the sensor element by the rod lens array. The image is read as an electrical signal by converting the intensity of the light into a voltage at the sensor unit. Since the CIS is a one-dimensional line sensor, the document or the CIS is moved, and each time a one-dimensional image is read, a two-dimensional image is acquired and image processing is performed.

In the case of a color image, the same image is read for each of the three primary colors (RGB). Generally, the light source is provided for the three primary colors and the light source is switched sequentially, or the sensor unit is prepared for the three primary colors. In combination with a color filter, data is acquired for each color, and they are combined and converted into a color image.

Incidentally, FIG. 1 (see Patent Document 1) of Japanese Patent Application Laid-Open No. 2003-251858 describes a lens array unit that positions a light emitting surface, a lens array, and a light receiving surface and corrects the warpage of the lens array.

JP 2003-251858 A (FIG. 1)

However, the lens array unit 1 described in Patent Document 1 includes a lens holder that holds a lens array 2, a lens array 2, and a pair of positioning pins 4 having first and second reference surfaces 4a and 4b at both end surfaces. 3, the first reference surface 4 a is brought into contact with the reference surface on the light emitting surface side, and the second reference surface 4 b is brought into contact with the reference surface on the light receiving surface side, whereby the light emitting surface, the lens array 2 and the light receiving surface are received. Although the relative position of the surface is determined, there is no specific description regarding the positioning of the lens array and the light receiving element on the light receiving surface side.

  By positioning the relative positions of the individual lenses and the light receiving elements constituting the lens array, the present invention reduces image variations in individual CISs due to optical coupling between the lens array and the light receiving elements, and the image quality is uniform. An object of the present invention is to provide an image sensor capable of reading a high-precision image.

An image sensor according to a first aspect of the present invention includes a light source that irradiates light on a document, a plurality of lenses arranged in a main scanning direction of the document, and a lens array that converges light reflected or transmitted by the document, A plurality of sensor elements that receive light converged by the lens array are linearly arranged, and a sensor substrate provided with a reference position mark on the arranged extension line, and a through-hole surrounded by the sensor element A support member that forms a hole and supports the lens array by attaching the lens array to the through hole; and a positioning member that is provided on the sensor substrate in accordance with the reference position mark and positions the support member. is there.

The image sensor according to a second aspect is the image sensor according to the first aspect, wherein the positioning member is implanted perpendicularly to the sensor substrate and is brought into contact with the support member.

  The image sensor according to a third aspect is the one according to the first aspect, wherein the positioning member is a cylindrical or prismatic pin, and the pin is inserted into a hole formed in the support member.

  According to a fourth aspect of the present invention, there is provided a light source for irradiating light on a document, a plurality of lenses arranged in the main scanning direction of the document, and a lens array for converging light reflected or transmitted by the document, A plurality of sensor elements that receive light converged by the lens array are linearly arranged, and a sensor substrate provided with a reference position mark on the extended line, and grooves that are open at both ends corresponding to the sensor elements are provided. And a support member that is mounted and supported by mounting the lens array in the groove, and a positioning member that is provided on the sensor substrate in alignment with the reference position mark and positions the lens array.

  An image sensor according to a fifth aspect is the image sensor according to the fourth aspect, wherein the positioning member is implanted perpendicularly to the sensor substrate and is brought into contact with the lens array.

  The image sensor according to a sixth aspect is the one according to the first or fourth aspect, wherein the reference mark has a cross shape, and the positioning member is provided at an intersection thereof.

  The image sensor according to a seventh aspect is the one according to the fourth aspect, wherein concave portions are formed at both ends of the lens array, and the positioning member is inserted into the concave portions.

According to the present invention, by inserting the positioning pin into the reference hole provided in the sensor substrate and the housing, the relative position between the light receiving element and the lens becomes constant over the moving direction and the reading direction of the document. Variations in relative position during assembly of individual CISs are reduced, and an image sensor with stable image quality can be obtained.

Further, according to the present invention, the positioning pin is inserted into the concave portion of the lens array and the positioning pin is abutted against the abutting reference position, so that the optical dimensional accuracy in the optical axis direction can be improved, and high image quality without blurring can be achieved. It is possible to obtain an image sensor that performs reading.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of an image sensor according to Embodiment 1. In FIG. 1, 1 is a light source that emits light, 1a is a light emitting portion of the light source 1, and 2 is glass that transmits light from the light source 1. A transparent body composed of a plate, 3 is an object to be irradiated such as a document or banknote, and 4 is a lens array (rod lens array) for converging light from the document 3, and a large number of cylindrical plastic lenses are flexible. It is sealed with a plastic material and is integrally molded. Reference numeral 5 denotes a light receiving element (sensor element) constituted by a sensor IC or the like, which includes a photoelectric conversion unit and a driving circuit thereof. 6 is a sensor substrate on which a plurality of light receiving elements 5 are linearly arranged, 7 is a housing (supporting member) that houses or supports the light source 1, the lens array 4 and the sensor substrate 6, and 8 is a housing 7 for housing the sensor substrate 6. The pressure-sensitive adhesive tape 9 is a pressure-sensitive adhesive tape, 9 is a document transport roller for transporting the document 3, 10 is a document guide, and the document transport roller 9 and the document guide 10 are not normally incorporated in the CIS.

A path reaching the light receiving element 5 including the rod lens array 4 that converges the light from the document 3 is called an optical path or an optical axis. Further, the distance (Z) from the original 3 to the light receiving element 5 is called an optical conjugate length, the distance (L) between the original 3 and the original 3 side end of the rod lens array 4 and the opposite end of the rod lens array 4. The distance (L) between the light receiving element 5 and the light receiving element 5 is preferably optically the same distance (dimension).

FIG. 2 is a plan view of the contact image sensor according to the first embodiment. In FIG. 2, reference numeral 11 denotes a power source for driving the light source 1 and the light receiving element 5, and a connector for interface of input / output signals. Reference numeral 12 denotes SUS. It is the positioning pin (positioning member) comprised.

FIG. 3 is a plan configuration diagram of the sensor substrate 6 of the contact image sensor according to the first embodiment, 13 is an electronic component such as a capacitor, and 14 is a hole with a diameter of 1.0 mm provided at both ends of the sensor substrate 6. (First pair of holes), 15 is a target mark (reference position mark) formed by a pattern, and 16 is a conductor land connected to the connector 11.

  FIG. 4 is a plan view seen from the mounting surface of the sensor substrate 6 of the housing 7 of the contact image sensor according to the first embodiment, and the mounting position of the rod lens array 4 is also displayed for reference. 7a is a hole (second pair of holes) having a diameter of 1.0 mm provided at both ends of the housing 7, and 7b is provided in the central portion of the housing 7 to read light from the rod lens array 4. Wide hollow holes (through holes) opened along the (main scanning direction), 7c are provided in an installation area of the electronic component 13 and the like mounted on the sensor substrate 6 to prevent contact between the housing 7 and the electronic component 13. It is a wide hollow hole.

  FIG. 5 is an external perspective view of the end portion of the case 7 of the contact image sensor according to the first embodiment. FIG. 5A is an end view of the case 7 showing the rod lens array 4, the sensor substrate 6 and the positioning pins 12 as a reference. 7d is a detailed view of the part, and 7d is a CIS mounting hole. FIG. 5 b is an end schematic diagram of the housing 7 for explaining the positions of the positioning pins 12. The rod lens array 4 having a flexible outer skin is sandwiched between grooves of the casing 7 having substantially the same size as the rod lens array 4 provided on the upper portion (the document 3 side) of the wide through hole 7b of the casing 7. Accordingly, the rod lens array 4 can slide in the groove of the housing 7 in the main scanning direction. Further, the groove of the housing 7 is provided between the ends of the housing 7 in the main scanning direction. In FIG. 7 b, the position of the positioning pin 12 that passes through the sensor substrate 6 and the housing 7 is expressed. 1 to 5, the same reference numerals indicate the same or corresponding parts.

Next, the operation will be described. In FIG. 1 and FIG. 2, light emitted from a white light source 1 such as a fluorescent lamp passes through a transmissive body 2 and enters a document 3. Directly reflected light of the light incident on the document 3 is diffused at an angle corresponding to the angle incident on the document 3, but the scattered reflected light passes through the transmission body 2 and is converged by the rod lens array 4. The light converged at (1) enters the light receiving element 5 arranged on the sensor substrate 6. The light incident on the light receiving element 5 is photoelectrically converted and output from the connector 11 as a continuous analog serial signal via the drive circuit of the light receiving element 5.

Next, the assembly order of CIS will be described. In FIG. 3, the first pair of holes 14 provided in the sensor substrate 6 made of a printed wiring board is a reference hole having a diameter of 1.0 mm, and a pattern is formed around the reference hole in a cross shape. A mark 15 is installed. The sensor IC 5 is mounted by a die bonder device that recognizes the pattern of the target mark 15 and inputs numerically the installation position information of each sensor IC 5 from the target position. Therefore, the sensor ICs 5 installed in a straight line between the reference holes are mounted with an accuracy of ± 20 μm or less with respect to each of the surface directions of the sensor substrate 6.

Next, in FIG. 4, the second pair of holes 7 a provided in the casing 7 made of an aluminum drawn alloy has the same size as the first pair of holes 14 provided in the sensor substrate 6. It consists of. The sensor substrate 6 is mounted on the back surface of the housing 7 with the sensor IC 5 facing the document 3 side. The peripheral edge of the housing 7 is overlapped with the sensor substrate 6, and the positioning pins 12 shown in FIG. 2 are provided in the second pair of holes 7 a of the housing 7 and the first pair of holes 14 of the sensor substrate 6. insert. The positioning pin 12 has a diameter of 1.0 mm but is hollow inside, and has a notch reaching the inside along the extending direction of the pin, and is also called a spring pin. Therefore, it is inserted by being contracted by the elasticity of the pin, and the inserted positioning pin 12 is fitted into the hole by an elastic force.

Next, as shown in FIG. 5, the rod lens array 4 is sandwiched in the groove of the housing 7, the rod lens array 4 is slid in the groove of the housing 7, and the positioning pins 12 extending from the housing 7 are attached. Fix by contact (contact).

From the above, since the spring pin is used as the positioning pin 12, it is possible to easily insert the spring pin because the hole diameters of the housing 7 and the sensor substrate 6 are the same. Since the light receiving element 5 is mounted from the target mark 15 of the sensor substrate 6 as a reference, the mounting accuracy is high, and the hole 14 provided in the center of the target mark 15 of the sensor substrate 6 and the hole 7a of the housing 7 are provided. Are aligned by the spring pin 12, so that the positional accuracy of the groove of the casing 7, the surface of the original 3 and the light receiving surface sandwiching the rod lens array 4 is increased. And since the rod lens array 4 slides the groove | channel of the housing | casing 7 and contact | abuts to the spring pin 12, it becomes possible to attach the position of the light receiving element 5 and the rod lens array 4 except the optical axis direction with high precision. .

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a perspective view of the end of the rod array. In FIG. 6, reference numeral 41 denotes a rod lens array. A U-shaped groove (concave recess) is provided at the end of the rod lens array 41. In the first embodiment, the end portion of the rod lens array 4 is a flat surface, but in the second embodiment, a U-shaped groove having a width of 1.0 mm is formed at both end portions, and a positioning pin is inserted therein. . In FIG. 6, by positioning the positioning pin at the reference abutting position of the end of the rod lens array 41 on the side of the document 3, the dimension of the positioning pin in the height direction is set in advance, and the optical axis direction of the rod lens array 41 is set. By performing the adjustment, positioning in three directions can be performed.

That is, as shown in FIG. 7, in order to set the distance (L) between the light receiving surface side end of the rod lens array 41 and the light receiving surface of the light receiving element 5 to an optimum value, the total length of the positioning pins 121 of the rod lens array 41 is increased. By setting in advance and knowing the abutting portion of the end portion of the rod lens array 41 and the light receiving surface side size (A) of the rod lens array 41, the rod lens array 41 is light-transmitted in a groove sandwiched by the housing 7. Adjusted and fixed with respect to the axial direction. This fine adjustment is performed by operating the first pair of holes 14 exposed on the back surface of the sensor substrate 6.

Embodiment 3 FIG.
In the first and second embodiments, the spring pin is mainly described as the positioning pin, but in the third embodiment, a case where a prismatic pin is used will be described. FIG. 8 is an end perspective view of the rod lens array of the third embodiment. In FIG. 8, reference numeral 42 denotes a rod lens array, and a square groove (concave depression) is provided at the end of the rod lens array 42. In the third embodiment, a prismatic groove (concave portion) having a width of 1.0 mm is formed at both ends, and a positioning pin is inserted therein.

That is, as shown in FIG. 9, in order to set the distance (L) between the light receiving surface side end of the rod lens array 42 and the light receiving surface of the light receiving element 5 to an optimum value, the total length of the positioning pins 122 of the rod lens array 42 is increased. By setting in advance and knowing the reference abutting position of the end of the rod lens array 42 and the size (A) of the light receiving surface of the rod lens array 42, the rod lens array 42 is light-transmitted in a groove sandwiched between cases. Adjusted and fixed with respect to the axial direction. This fine adjustment is performed by operating the first pair of holes 14 exposed on the back surface of the sensor substrate 6, sealing the resin after adjustment, and fixing the prism 122 smaller than 1.0 mm. FIG. 10 is a plan view of the sensor substrate 61 according to the third embodiment. The sensor substrate 61 is provided with a pair of 1.0 mm square holes 141 at both ends. FIG. 11 is a plan view of the casing 71 in the third embodiment. The casing 71 is provided with a pair of holes 71a of 1.0 mm □ at both ends.

In Embodiments 2 and 3, U-shaped grooves and square grooves are provided at both ends of the rod lens array. However, as shown in FIG. 12, jaw-shaped protrusions are formed at the ends of the rod lens array 43. A reference abutting position may be provided, and as shown in FIG. 13, a reference abutting position is provided inside the rod lens array 44 outside the optical coupling region of the rod lens array 44, and the positioning pin 123 is abutted. Also good.

Embodiment 4 FIG.
In the first to third embodiments, the casings 7 and 71 are installed on the document 3 side and overlapped with the sensor substrates 6 and 61. In the fourth embodiment, a case where the sensor substrate is installed on the document 3 side will be described. . FIG. 14 is a plan view of an image sensor according to Embodiment 4, and 72 is a casing. FIG. 15 shows an AA cross section near the end. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In FIG. 15, the back surface of the sensor substrate 6 (on the side opposite to the light receiving element 5 mounting surface) is in contact with almost the entire surface of the housing 72, and the sensor substrate 6 is slid and inserted into the housing 72.

In the first to fourth embodiments, the light source 1 is a white light source. However, a single-spectrum monochromatic light source may be used, and an LED array light source or a light guide light source using a plurality of LEDs may be used for color reading. good.

In the first to fourth embodiments, the light emitted from the light source 1 is reflected on the document 3 and the scattered light is read. However, when a watermark such as a banknote is read, the transmission light source of the banknote 1 is used. It may be provided in the upper part and the transmitted light may be read by the light receiving element 5 through the lens array.

It is a cross-sectional block diagram of the image sensor by Embodiment 1 of this invention. It is a top view of the image sensor by Embodiment 1 of this invention. It is a top view of the sensor board | substrate of the image sensor by Embodiment 1 of this invention. It is a top view of the housing | casing of the image sensor by Embodiment 1 of this invention. It is a perspective view of the housing | casing edge part of the image sensor by Embodiment 1 of this invention. It is a perspective view of the lens array edge part of the image sensor by Embodiment 2 of this invention. It is a perspective view explaining the abutting method of the positioning pin of the image sensor by Embodiment 2 of this invention. It is a perspective view of the lens array edge part of the image sensor by Embodiment 3 of this invention. It is a perspective view explaining the butting method of the positioning pin of the image sensor by Embodiment 3 of this invention. It is a top view of the sensor board | substrate of the image sensor by Embodiment 3 of this invention. It is a top view of the housing | casing of the image sensor by Embodiment 3 of this invention. It is a perspective view of the lens array of the image sensor by other Embodiment of this invention. It is a side view of the lens array of the image sensor by other embodiment of this invention. It is a top view of the image sensor by Embodiment 4 of this invention. It is a cross-sectional block diagram of the image sensor by Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source, 1a Light emission part, 2 Transmitter, 3 Original (object to be irradiated), 4 Lens array (rod lens array), 5 Sensor element (light receiving element), 6 Sensor substrate, 7 Case (support member), 7a Hole (second pair of holes), 7b Through hole (hollow hole), 7c Hollow hole, 7d Mounting hole, 8 Tape, 9 Document transport roller, 10 Document guide, 11 Connector, 12 Positioning pin (positioning member), 13 Electronic component, 14 holes (pair of holes), 15 target mark (reference position mark), 16 connector land (conductor land), 41, 42, 43, 44 lens array, 71 housing (support member), 72 housing (support) Member), 121 positioning pin (positioning member), 122 prismatic pin (positioning member), 123 positioning pin (positioning member).

Claims (7)

A light source that irradiates light on the document, a plurality of lenses arranged in the main scanning direction of the document, a lens array that converges the light reflected or transmitted by the document, and the light converged by the lens array is received A plurality of sensor elements arranged in a straight line, and a sensor board provided with a reference position mark on the arranged extension line, and a through hole surrounded by the sensor element are formed, and the through hole is formed in the through hole. An image sensor comprising: a support member that mounts and supports the lens array; and a positioning member that is provided on the sensor substrate in accordance with the reference position mark and positions the support member. The image sensor according to claim 1, wherein the positioning member is implanted perpendicularly to the sensor substrate and is brought into contact with the support member. The image sensor according to claim 1, wherein the positioning member is a columnar or prismatic pin, and the pin is inserted into a hole formed in the support member. A light source that irradiates light on the document, a plurality of lenses arranged in the main scanning direction of the document, a lens array that converges the light reflected or transmitted by the document, and the light converged by the lens array is received A plurality of sensor elements arranged in a straight line, a sensor substrate provided with a reference position mark on the arranged extension line, and a groove open at both ends corresponding to the sensor element, and the lens array formed in the groove An image sensor comprising: a support member that is mounted and supported; and a positioning member that is provided on the sensor substrate in accordance with the reference position mark and positions the lens array. The image sensor according to claim 4, wherein the positioning member is implanted perpendicularly to the sensor substrate and is brought into contact with the lens array. 5. The image sensor according to claim 1, wherein the reference mark has a cross shape, and the positioning member is provided at an intersection thereof. 6. The image sensor according to claim 4, wherein concave portions are formed at both ends of the lens array, and the positioning member is inserted into the concave portions.

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