JP4396593B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus.

  2. Description of the Related Art Conventionally, a contact-type image reading apparatus including a spacer that keeps a distance between a document table and a contact-type image sensor module constant is known (see, for example, Patent Document 1). When the distance between the document table and the contact-type image sensor module is kept constant by the spacer, it is known that when the document is read, a so-called stick-slip is generated in which the spacer repeatedly slides on the board surface or gets caught by the board surface due to fluctuations in frictional force. ing. In the image reading apparatus described in Patent Document 1, stick slip is less likely to occur by setting the friction coefficient between the spacer and the transparent flat plate (original table) to a predetermined value or less.

  However, in the image reading apparatus described in Patent Document 1, the inner width w1 of the spacer formed in a gate shape, in other words, the width w1 between two legs is a contact type image sensor (contact type image sensor module). It is formed larger than the width w2 in the sub-scanning direction. For this reason, a gap is generated between the leg portion and the contact image sensor module. Even if the friction coefficient is set to a predetermined value or less, even if the spacer slides on the document table, vibration occurs even if it is slight, so there is a gap between the legs and the contact image sensor module. There is a problem that a slight vibration is transmitted to the legs and is amplified, whereby the legs touch or move away from the contact image sensor module, thereby increasing the vibration of the image sensor. When the image sensor vibrates, the reading position is shifted, so that a good image reading operation cannot be performed.

JP 2003-75936 A

  The present invention has been created in view of the above-described problems, and an object thereof is to provide an image reading apparatus capable of reducing the vibration of an image sensor and performing a good reading operation.

(1) An image reading apparatus for achieving the above object includes a transparent manuscript table on which a manuscript is placed and a first manuscript that is provided below the manuscript table and is placed on the manuscript table. A linear image sensor, a sensor case on which the first linear image sensor is mounted, a biasing unit that biases the sensor case toward the document table, and the sensor case as the first linear image. A transport unit that transports the sensor in the sub-scanning direction perpendicular to the longitudinal direction of the sensor, a spacer that maintains a constant distance between the document table and the sensor case, and a spacer having legs that clamp the sensor case in between. .
According to the present invention, since the spacer is clamped with the sensor case sandwiched between the legs, the legs and the sensor case are always in close contact with each other, and the image is obtained by the legs contacting or leaving the contact image sensor module. Amplifying the vibration of the sensor can be prevented. Therefore, according to the present invention, the vibration of the image sensor during reading can be reduced, and a good image reading operation can be performed.

(2) A second linear image sensor mounted on the sensor case for reading a transparent document placed on the document table, the first linear image sensor being spaced apart from the first linear image sensor in the sub-scanning direction. The linear image sensor further includes a second linear image sensor extending in parallel to the linear image sensor, wherein the spacers are attached to both ends of the sensor case in the longitudinal direction, and the two spacers attached to one end are sub-portions. They may be arranged and attached in the scanning direction.
According to the present invention, one of the two spacers attached to one end adjusts the distance between the document table and the first linear image sensor, and the other adjusts the distance between the document table and the second linear image sensor. By adjusting, the distance between the document table and the first linear image sensor and the distance between the document table and the second linear image sensor can be independently adjusted.

(3) The leg portion may be elastically deformable, and may have a convex portion that abuts on the sensor case and elastically deforms the leg portion toward the non-sensor case side.
(4) The leg portion may be elastically deformable, and the sensor case may have a convex portion that protrudes in a sub-scanning direction and abuts on the leg portion to elastically deform the leg portion toward the anti-sensor case side. .

Hereinafter, embodiments of the present invention will be described based on a plurality of examples. In each of the embodiments, the component having the same reference sign corresponds to the component of the other embodiment having the reference sign.
(First Example)
FIG. 2 is a schematic diagram of an image scanner 1 as an image reading apparatus according to an embodiment of the present invention.

  The document table 10 is formed of a transparent plate such as a generally rectangular glass plate, and closes the opening of the housing 8 from below. A reflective original such as a printed document or a photograph or a transparent original such as a photographic film is placed on the surface 10 a of the original table 10. However, the photographic film is not placed directly on the document table 10, but is placed in a state of being held by a holder that holds the photographic film. Here, a 35 mm film will be described as an example of a photographic film. The 35 mm film is held at a distance of 1 mm upward from the board surface 10 a in a posture extending in parallel with the longitudinal axis of the guide rod 20 by the holder.

The document cover 16 is connected to the housing 8 so as to be rotatable between a closed posture in which the hinge 9 covers the plate surface 10a of the document table 10 and an open posture in which the plate surface 10a is opened.
The transparent document illumination unit 18 is disposed on the document table 10 side of the document cover 16. The transmissive original illuminating unit 18 includes a fluorescent tube lamp, a reflector, a diffusion plate and the like (not shown). The fluorescent tube lamp is arranged such that its longitudinal axis extends parallel to the longitudinal axis of the guide rod 20. The light emitted from the fluorescent tube lamp is reflected by the reflector, diffused by the diffusion plate, and illuminates the transmission original placed on the original table 10 with uniform illuminance.

Although not shown in FIG. 2, a document mat is detachably supported on the document table 10 side of the document cover 16. The original mat is attached to the original cover 16 when reading a reflective original, and is removed when reading a transparent original.
In the housing 8, the contact image sensor module 2, a carriage 22 on which the contact image sensor module 2 is mounted, a guide rod 20 that is laid in the sub-scanning direction and supports the carriage 22 slidably, and the carriage 22 is the guide rod 20. A sub-scanning drive unit 52 that transports in the sub-scanning direction parallel to the head is accommodated. The contact image sensor module 2 is supported on a carriage 22 by a spring 77 as an urging unit, and is urged toward the document table 10 by the spring 77.

  FIG. 3 is a perspective view of the inside of the housing 8. The housing 8 is composed of a lower member 8a and an upper member (not shown), and FIG. 3 shows a state where the upper member is removed. The carriage 22 is slidably supported by the guide rod 20, and is further engaged with a drive belt 52c that is spanned between a pulley 52b (see FIG. 2) and the pulley 52a. The pulley 52b is driven by a stepping motor 52d. When the stepping motor 52d rotates, the carriage 22 moves along the guide rod 20 in the sub-scanning direction. The stepping motor 52d is an example of a drive source, and may be a DC motor or the like.

Next, details of the contact image sensor module 2 will be described.
4A and 4B are schematic views of a cross section of the contact image sensor module 2. The contact image sensor module 2 includes a reflective original illumination unit 24, a first Selfoc lens array (SLA) 26, a first linear image sensor 30, a substrate 40, a second SLA 28, a second linear image sensor 32, and a substrate. 42 and a long and thin box-shaped sensor case 70 for housing them.

  The reflective original illumination unit 24 includes a red LED, a green LED, a blue LED, and a light guide (not shown). The reflection document illumination unit 24 lights up red LED, green LED, and blue LED in a time-sharing manner, and the light emitted from the LED is guided to the document table 10 side by the light guide to illuminate the reflection document 4. The light guide is formed of a light transmissive member such as glass. The reflection original illumination unit 24 may be a fluorescent lamp.

The first SLA 26 has a plurality of cylindrical lenses (rod lenses) 36 arranged in a straight line in the main scanning direction perpendicular to the guide rod 20. The first SLA 26 forms an optical image on the scanning line by the light emitted from the reflection original illumination unit 24 and reflected by the reflection original 4 on the light receiving surface of the first linear image sensor 30 at an equal magnification.
The first linear image sensor 30 includes a plurality of light receiving elements 31 and MOS transistor switches arranged linearly in parallel with the first SLA 26. The first linear image sensor 30 scans the optical image of the reflective original 4 formed by the first SLA 26 in synchronization with the lighting of each color LED, and outputs an electrical signal correlated with the density of the optical image of that color. To do. The width in the longitudinal direction of the arrangement range of the light receiving elements 31 arranged in the first linear image sensor 30 is 218 mm so that an A4 size document and an A4 letter size document can be read. The resolution of the first linear image sensor 30 is 1200 dpi that can sufficiently reproduce the image information recorded on the reflective original 4.

Similarly, the second SLA 28 has a plurality of rod lenses 38 arranged linearly in the main scanning direction. The second SLA 28 forms an optical image on the scanning line by the light irradiated from the transmission original illumination unit 18 and transmitted through the 35 mm film 6 on the light receiving surface of the second linear image sensor 32 at the same magnification. As shown in FIG. 4B, the 35 mm film 6 is supported and placed on the holder 14.
The second linear image sensor 32 includes a plurality of light receiving elements 33, MOS transistor switches, and the like arranged in three rows in parallel with the second SLA 28, and color filters 44r, 44g, and 44b having different colors for each row. Is provided. Specifically, the color of the color filter 44 is, for example, three colors of red, green, and blue. As a result, the white light emitted from the transmissive original illumination unit 18 can be separated into red light, green light, and blue light. The second linear image sensor 32 scans the optical image of the 35 mm film 6 formed by the second SLA 28 and outputs an electrical signal correlated with the density of the optical image. The width in the longitudinal direction of the arrangement range of the light receiving elements 33 arranged in the second linear image sensor 32 is 27 mm that allows reading of a 35 mm film. The resolution of the second linear image sensor 32 is 2400 dpi that can sufficiently reproduce the image information recorded on the 35 mm film. The size (pixel size) of the light receiving element 33 of the second linear image sensor 32 is smaller than the light receiving element 31 of the first linear image sensor 30. In the second linear image sensor 32, the pitch of the light receiving elements 33 is reduced by the amount of the pixel size. Therefore, when the second linear image sensor 32 is used, the resolution is higher than that of the first linear image sensor 30. Image data can be created.

  The second SLA 28 and the second linear image sensor 32 are for reading a transparent original. Since the transparent original is placed 1 mm away from the original table 10 as described above, the second SLA 28 and The second linear image sensor 32 is arranged so as to be shifted by 1 mm above the first SLA 26 and the first linear image sensor 30.

FIG. 5 is a block diagram illustrating a hardware configuration of the image scanner 1.
The main scanning drive unit 50 outputs drive pulses necessary for driving the first linear image sensor 30 and the second linear image sensor 32 to the first linear image sensor 30 and the second linear image sensor 32. It is a drive circuit. The main scanning drive unit 50 includes, for example, a synchronization signal generator, a driving timing generator, and the like.

  The sub-scanning drive unit 52 as a transport unit includes a guide rod 20, a pulley 52a, a pulley 52b, a drive belt 52c, a stepping motor 52d, a plurality of gears that transmit the rotational driving force of the stepping motor 52d to the pulley, a drive circuit (not shown), and the like. Is provided. When the stepping motor 52d pulls the carriage 22 by the drive belt 52c, the first linear image sensor 30 and the second linear image sensor 32 and the reflection original or the 35 mm film are relatively moved. As a result, a two-dimensional image can be scanned.

  The AFE (analog front end) unit 54 includes an analog signal processing unit (not shown), an A / D converter, and the like. The analog signal processing unit subjects the electrical signals output from the first linear image sensor 30 and the second linear image sensor 32 to analog signal processing such as amplification and noise reduction processing, and outputs the result. The A / D converter quantizes the electrical signal output from the analog signal processing unit into an output signal in a digital representation having a predetermined bit length, and outputs the output signal.

The digital image processing unit 56 performs image processing such as gamma correction, interpolation of defective pixels by a pixel interpolation method, shading correction, image signal sharpening, color space conversion, and the like on the output signal output from the AFE unit 54.
The interface unit 58 is configured in accordance with a communication standard such as RS-232C, Bluetooth, or USB. The image scanner 1 can be communicably connected to a personal computer (PC) (not shown) through the interface unit 58.

  The control unit 60 includes a CPU 62, a ROM 64, and a RAM 66. The CPU 62 executes computer programs stored in the ROM 64 to control each unit of the image scanner 1. The ROM 64 is a memory that stores various programs and data, and the RAM 66 is a memory that temporarily stores various programs and data.

Next, a spacer that keeps the distance between the contact image sensor module 2 and the document table 10 constant will be described.
FIG. 6 is a perspective view of the contact image sensor module 2. As shown in the figure, the sensor case 70 has attachment portions 72 for attaching spacers 71 to both ends in the longitudinal direction. The attachment portion 72 is formed in a rectangular plate shape, and is provided in the sensor case 70 in a posture in which the long side is parallel to the sub-scanning direction. A recess 73 is formed in the approximate center of the upper side of the attachment portion 72. The attachment portion 72 is partitioned into a first attachment portion 72a on the left side and a second attachment portion 72b on the right side with the recess 73 interposed therebetween, and a spacer 71 is attached to each of them. Since two spacers 71 are arranged and attached to one end in the sub-scanning direction, the distance between the document table 10 and the first linear image sensor 30 is adjusted on one side of the two spacers 71, and the document table 10 is adjusted on the other side. By adjusting the distance from the second linear image sensor 32, the distance between the document table 10 and the first linear image sensor 30 and the distance between the document table 10 and the second linear image sensor 32 are made independent. Can be adjusted.

  FIG. 7 is a front view of the spacer 71 before being attached to the attachment portion 72. The spacer 71 is formed of resin or the like so as to be elastically deformable, and includes a base portion 71a that extends linearly, a first leg portion 71b that extends perpendicularly from one end of the base portion 71a, and a first leg from the other end of the base portion 71a. It has the 2nd leg part 71c extended perpendicularly | vertically in the same direction as the leg part 71b. A substantially trapezoidal protruding portion 71d is formed in the base portion 71a as shown in the figure. The second leg 71c extends longer than the first leg 71b, and a claw 71e is formed at the tip. The second leg portion 71c is formed with a convex portion 71f that protrudes toward the first leg portion 71b.

  FIG. 1 is a front view showing the spacer 71 attached to the attachment portion 72. In the spacer 71, the first leg 71 b is accommodated in the recess 73 of the attachment portion 72, and the claw portion 71 e of the second leg portion 71 c is engaged with the attachment portion 72 in a state of being caught on the lower surface of the attachment portion 72. It is attached. In the spacer 71, the base 71a and the claw 71e are in contact with the attachment 72, respectively, so that the vertical movement is restricted, and the first leg 71b and the second leg 71c are respectively in contact with the attachment 72. The movement in the lateral direction is restricted by the contact.

  The interval between the first leg portion 71b and the convex portion 71f is formed narrower than the interval between the side surface 72c of the attachment portion 72 and the side surface 72d on the concave portion 73 side. When the spacer 71 is attached to the attachment portion 72, the second leg portion 71c is elastically deformed to the side away from the attachment portion 72 as shown in the figure by the convex portion 71f contacting the side surface 72c. Since the elastically deformed second leg portion 71c attempts to return to the original posture, the attachment portion 72 is clamped between the first leg portion 71b and the second leg portion 71c.

Next, the operation of the spacer 71 will be described.
FIG. 8 is a sectional view of the image scanner 1 and shows a section perpendicular to the sub-scanning direction. As described above, the contact image sensor module 2 is biased toward the document table 10 by the spring 77. When the contact image sensor module 2 is urged toward the document table 10, the protruding portions 71 d of the spacers 71 attached to both ends abut against the platen surface 10 b of the document table 10 as illustrated. As a result, the distance between the sensor case 70 and the document table 10 is held constant by the spacer 71. For example, when the distance between the first SLA 26 and the document table 10 is shifted due to a manufacturing error, and the document is not in focus, the distance is adjusted by exchanging with another spacer 71 having a different protruding portion 71d height. Therefore, it is possible to easily focus on the document.

  When the user instructs reading, the control unit 60 controls the stepping motor 52d to read the document while outputting the image data while moving the carriage 22 in the sub-scanning direction perpendicular to the paper surface. At this time, the overhanging portion 71 d slides in contact with the lower surface of the document table 10. Since the projecting portion 71d slides relative to the document table 10, it slightly vibrates. However, since the spacer 71 is fastened by the first leg 71b and the second leg 71c sandwiching the attachment part 72, the first leg 71b and the second leg 71c are always in close contact with the attachment part 72. Thus, even if the overhanging portion 71d vibrates, the vibration is not amplified by the first leg portion 71b and the second leg portion 71c.

  According to the image scanner 1 according to the first embodiment of the present invention described above, the first leg 71b and the second leg 71c are clamped with the mounting part 72 interposed therebetween, so that the first leg 71b and the first scanner 71 are attached. The part 72, the second leg 71c, and the mounting part 72 are always in close contact with each other, and the first leg 71b and the second leg 71c are in contact with or away from the contact image sensor module 2. As a result, it is possible to prevent the vibration of the image sensor from being amplified. Therefore, according to the present invention, the vibration of the first linear image sensor 30 or the second linear image sensor 32 during reading can be reduced, and a good image reading operation can be performed.

  In the first embodiment, as described above, the two spacers 71 are arranged and attached to one end of the contact image sensor module 2 in the sub-scanning direction. When two spacers 71 are arranged at one end in the sub-scanning direction, the width in the sub-scanning direction per spacer 71 must be shortened due to space restrictions. When the width of the spacer 71 in the sub-scanning direction is shortened, the spacer 71 becomes unstable with respect to stick slip, and vibration is likely to occur. However, since the spacer 71 of the first embodiment prevents vibration by the convex portion 71f, vibration can be prevented even if the width in the sub-scanning direction is shortened.

(Second embodiment)
FIG. 9 is a schematic view of the mounting portion 72 according to the second embodiment of the present invention. In the first embodiment described above, the case where the convex portion 71f is provided on the second leg portion 71c has been described as an example. However, as shown in FIG. 9, the convex portion 71f is attached to the attachment portion 72 instead of the second leg portion 71c. May be. Even if the convex portion 71f is provided on the attachment portion 72, substantially the same effect as that obtained when the convex portion 71f is provided on the second leg portion 71c can be obtained. The second embodiment is substantially the same as the first embodiment in other points.

(Third embodiment)
FIG. 10 is a schematic view of a spacer 80 according to the third embodiment of the present invention. The spacer 80 has a shape in which two spacers 71 of the first embodiment are combined. Only one spacer 80 is attached to each end of the contact image sensor module 2. The third embodiment is substantially the same as the first embodiment in other points.

(Fourth embodiment)
FIG. 11 is a schematic view of a spacer 90 according to the fourth embodiment of the present invention. The fourth embodiment is a modification of the first embodiment. The spacer 90 does not include the convex portion 71f, and when the spacer 90 is not attached to the attachment portion 72, the second leg portion 71c is inclined in a direction approaching the first leg portion 71b as illustrated. The spacer 90 is attached in a state where the second leg 71c is elastically deformed on the side away from the first leg 71b. Therefore, the spacer 90 is in a state where the attaching portion 72a or 72b is clamped between the first leg portion 71b and the second leg portion 71c. The fourth embodiment is substantially the same as the first embodiment in other points.

The front view of the spacer which concerns on the 1st Example of this invention. 1 is a schematic diagram of an image reading apparatus according to a first embodiment of the present invention. 1 is a perspective view of the inside of an image reading apparatus according to a first embodiment of the present invention. (A) And (B) is a schematic diagram of the cross section of the contact | adherence image sensor module which concerns on 1st Example of this invention. 1 is a block diagram of an image reading apparatus according to a first embodiment of the present invention. 1 is a perspective view of a contact image sensor module according to a first embodiment of the present invention. The front view of the spacer which concerns on the 1st Example of this invention. 1 is a schematic cross-sectional view of an image reading apparatus according to a first embodiment of the present invention. The schematic diagram of the spacer which concerns on the 2nd Example of this invention. The schematic diagram of the spacer which concerns on the 3rd Example of this invention. The schematic diagram of the spacer which concerns on 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image scanner (image reading apparatus), 10 Document stand, 22 Carriage (biasing unit), 30 1st linear image sensor, 32 2nd linear image sensor, 52 Subscanning drive part (conveyance unit), 70 Sensor case , 72 Mounting part (sensor case), 71 spacer, 71b, 71 leg part, 71f convex part, 77 spring (biasing unit), 80 spacer, 90 spacer

Claims (1)

A transparent platen on which the document is placed;
A first linear image sensor that is provided below the document table and reads a reflection document placed on the document table;
A sensor case on which the first linear image sensor is mounted;
An urging unit for urging the sensor case toward the original platen;
A transport unit that transports the sensor case in a sub-scanning direction perpendicular to the longitudinal direction of the first linear image sensor;
A spacer for maintaining a constant distance between the document table and the sensor case, and a spacer having a leg portion to be clamped with the sensor case interposed therebetween;
A second linear image sensor mounted on the sensor case for reading a transparent original placed on the original table, the first linear image being separated from the first linear image sensor in a sub-scanning direction. A second linear image sensor extending parallel to the sensor,
Two spacers are attached to both ends in the longitudinal direction of the sensor case, and the two spacers attached to one end are arranged and attached in the sub-scanning direction;
An image reading apparatus, wherein the two spacers can be independently replaced.

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