JPH0743738U - Document reader - Google Patents

Abstract

(57) [Abstract] [Purpose] Includes a reading unit that reads an original image displayed on the original while feeding the original in one direction, and an original placement table that supports the original by a document support surface and guides it to the reading unit. In the document reading device, the contamination of the document due to the adhesion of dust or dust is avoided as much as possible. A large number of ribs 89 extending in the document feeding direction are provided in a portion of the recording paper cover 20 that functions as the document placing table 26, and the document supporting surface is formed by the top surfaces of the ribs 89. The contact area between the original and the original placing table 26 is reduced, and even if dust or dust is present on the original placing table 26, the possibility that these will adhere to the original is reduced, and the original can be satisfactorily avoided. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device such as a copying machine or a facsimile device, and more particularly, to preventing stains on a document.

[0002]

[Prior art]

 Copiers, facsimile machines, etc. are provided with a document reading device for reading an image displayed on the surface of a document. This document reading device includes a reading unit that feeds a document in one direction and reads the original image displayed on the document, and also includes a document supporting member that supports the document by a document supporting surface and guides the document to the reading unit. Is composed of. In the past, the document supporting member was supposed to support the document on a flat document supporting surface.

[0003]

[Problems to be solved by the device]

 However, when the document supporting surface is flat, dust or dust (hereinafter referred to as dust) adheres to the document and the document is easily soiled. If the document supporting surface is flat, the document and the document supporting surface come into contact with each other over a wide area. On the other hand, since the document supporting surface is formed upward for that purpose, dust and the like are likely to accumulate. Therefore, the fact that the original comes into contact with the original supporting surface over a large area means that the original is likely to come into contact with dust and the like, and that the original is easily soiled. If the original is dirty, it is read and the quality of the recorded image deteriorates. Not only that, but dust or the like may adhere to the original document and be carried to the reading unit, which may stain the reading unit. If the original is dusty, the quality of the recorded image corresponding to the original will only deteriorate, but if the reading section is dirty, the quality of all recorded images will decrease. Therefore, the problem is particularly serious.

When the document is placed face down on the document support member, dust or the like is attached to the surface of the document on which the image is displayed, and the reading unit is arranged on the front side of the document. Therefore, the dust, etc. carried in by the original will directly pollute the reading unit. However, even if the document is placed face-up on the document support member and dust or the like adheres to the back surface of the document, the dust or the like will still be carried around the reading unit, and this dust or the like will eventually disappear. It may stain the scanning unit. Therefore, the present invention has an object to obtain an original reading device capable of satisfactorily avoiding contamination of an original due to adhesion of dust or the like.

[0005]

[Means for Solving the Problems]

 The gist of the present invention is to provide a plurality of ribs parallel to the document feeding direction on the document supporting member in the document reading device including the above-mentioned reading unit and the document supporting member, and the top surfaces of the ribs. The document supporting surface is formed by.

[0006]

[Action]

 If the document is supported by the ribs, the contact area between the document and the document supporting member can be reduced, and the possibility that the document is contaminated can be reduced accordingly. Even if dust or the like is present on the original document support member, most of them are on the surface that does not come into contact with the original document, so that they do not adhere to the original document. In that sense, it is desirable to make the area of the rib top surfaces as small as possible, and to make the total area of the rib top surfaces smaller than 1/2 of the area of the region where the ribs are formed. desirable. Further, although it is better that the rib is not formed only on a part of the document supporting member in the document feeding direction, it is preferable to form the rib over the entire length in the document feeding direction. If the reading unit reads the original image displayed on the side of the document that contacts the document supporting surface, the dust and the like adhering to the document will be read by the reading unit and the quality of the recorded image will deteriorate. Further, since the reading unit is directly contaminated by dust or the like attached to the document, the significance of applying the present invention is particularly great.

[0007]

EFFECTS OF THE INVENTION According to the present invention, it is possible to favorably prevent dust or the like from adhering to a document, so that the quality of a recorded image can be improved. In addition, since the dirt of the reading unit can be reduced, the number of times of cleaning the reading unit and its surroundings can be reduced. Moreover, since the ribs are formed parallel to the document feeding direction, the ribs do not hinder the document feeding, and when the document is positioned at a predetermined position on the document supporting member, the document is not supported on the document supporting member. However, forming the ribs in parallel with the feed direction facilitates slippage of the document in this case, because the component in the feed direction when reading the document is usually the largest. It is also desirable from the viewpoint of

[0008]

【Example】

 Hereinafter, the case where the present invention is applied to a document reading device of a facsimile machine will be described as an example with reference to the drawings. FIG. 3 is a view showing the outer appearance of the facsimile apparatus. As shown in FIGS. 1 and 4, the main body 12 of this apparatus includes a container-shaped lower cover 14 and an upper cover 16 that covers the lower cover 14. An opening 17 is provided in the upper cover 16, and the opening 17 is covered with an operation panel 18 and a recording paper cover 20 in order from the rear part. A receiver 21 is attached to the upper surface of the portion of the upper cover 16 surrounding the opening 17. The operation panel 18 and the recording paper cover 20 are both rotatably attached to the lower cover 14 about axes parallel to each other, and can be opened and closed independently without interfering with each other. The operation panel 18 is inclined downward toward the recording paper cover 20. On the upper surface thereof, numeric buttons 22 and the like for operating the telephone and operation buttons 24 and the like for manuscript transmission / reception operation are separated on the left and right sides of the operation panel 18. It is set up. Therefore, at the time of operation, it is possible to perform concentrated button operations on the left side and the right side of the operation panel 18 according to the purpose of use, and it is easy to operate, and each of these buttons 22 and 24 has one function. Since it is provided, the operation is easy and there is little risk of erroneous operation. Also, the tilted operation panel 18 makes it easy to see the buttons 22 and 24 and is easy to operate. There is.

The recording paper cover 20 covers a portion of the opening 17 that constitutes the recording paper inlet / outlet port 25 (see FIG. 1), and a front portion thereof is inclined downward to form an operation panel. The portion on the 18 side is a document placing table 26 parallel to the bottom wall of the lower cover 14. As shown in FIG. 4, in the space 27 in the main body 12, the power source 28 is accommodated in the portion covered by the upper cover 16, and the reading unit 30 is provided in the portion covered by the operation panel 18. The recording unit 32 is provided in a portion covered by the cover 20. The reading unit 30 and the recording unit 32 will be described below.

Inside the operation panel 18, as shown in FIG. 5, an operation panel substrate 34 having fixed contacts of a plurality of switches opened and closed by the buttons 22 and 24 is provided, and a manuscript 36 is provided. A guide plate 38 for guiding the is attached. The original 36 is placed on the original placing table 26 with the side on which the image is recorded facing down, and is fed from the front side of the apparatus to the rear side thereof. The original 36 is placed at two positions separated by a distance in the original feeding direction of the guide plate 38. A small-diameter roller 40 is rotatably provided, and a document pressing member 42 is provided between the small-diameter rollers 40. A frame 43 is provided in the lower cover 14, and a part of the frame 43 serves as a guide portion 44 for guiding the original 36 together with the guide plate 38. A large-diameter roller 46 is rotatably attached to a portion of the guide portion 44 corresponding to the two small-diameter rollers 40. The small-diameter roller 40 is pressed against the large-diameter roller 46 with the operation panel 18 closed, and the large-diameter roller 46 is rotated by a drive motor (not shown) to rotate the small-diameter roller 40 and the original document. 36 is sent. The rollers 40 and 46 and the drive motor constitute a feeding device.

A reading head 50 is arranged in a portion corresponding to the document pressing member 42. The read head 50 is an optical type using an optical fiber, and can read black and red images described on a white background. The reading head 50 has an elongated shape that is longer than the width of the original document 36 (the dimension in the direction perpendicular to the original document feeding direction), and the head main body 52 has a large number of (mainly as shown in FIG. 7 conceptually. In the embodiment, 104 light emitting fibers 56 are arranged along the longitudinal direction. The light emitting fiber 56 is covered with a cover (not shown), but its tip portion is, as shown in FIG. 8, formed on an end surface (reading surface) 58 of the head body 52 facing the document pressing member 42 at equal intervals (in this embodiment). In the example, they are exposed by 2 mm apart. Spacers 62 and 64 (see FIG. 5) are attached to the upper and lower portions of the head main body 52 in the document feeding direction, respectively, so that the reading surface 58 is separated from the document pressing member 42 by a certain distance. It is designed to be kept.

On the other hand, a photodiode as a light emitting element is opposed to each of the base ends of the light emitting fibers 56. The light emitting element is fixed to the circuit board 68 fixed to the head main body 52 through the lamp house 66. In this embodiment, the red light emitting element 70R that emits red light and the yellow light emission that emits yellow light. Two types of elements 70Y are arranged every other one. Each of the light emitting elements 70R and 70Y is fitted into the through hole 72 of the lamp house 66 so as to be shielded from each other. When reading the original 36, two colors of light, red light and yellow light, are emitted. It is done by

Further, a light receiving fiber 74 is arranged corresponding to each of the light emitting fibers 56. Each tip of these light receiving fibers 74 is exposed adjacent to the tip of each light emitting fiber 56 on the reading surface 58 as shown in FIG. 8, while the proximal end side has 10 fibers as shown in FIG. Alternatively, 14 groups are grouped into 8 groups, and each group is opposed to one light receiving element 76. A silicon photodiode is used for the light receiving element 76, and is mounted on the circuit board 68. The light emitted from the light emitting fiber 56 by the light emission of the light emitting elements 70R and 70Y illuminates the original document 36, and the reflected light from the original document 36 enters the light receiving element 76 via the light receiving fiber 74. As shown in FIG. 9, the light receiving element 76 is connected to a conversion unit 80 that converts a current into a voltage. The voltage converted by the conversion unit 80 is amplified by an amplification unit 82 and then binarized circuit unit. At 84, it is compared with a reference value, and depending on whether it is higher or lower than the reference value, it is converted into a binary signal of high level and low level, and stored in a memory for reading data storage provided in a RAM of a computer (not shown). It The computer is also configured to control the light emission timings of the light emitting elements 70R and 70Y, and constitutes the reading unit 30 together with the reading head 50.

The outside of the circuit board 68 is covered with a noise preventing shield member 88, as shown in FIG. Further, as shown in FIG. 6, the original placing table 26 is provided with a large number of ribs 89 having a height of 1 mm and extending in the original feeding direction. When the original 36 is fed, the original placing table 26 is provided. Dust, dust, etc. on 26 are prevented from adhering to the original document 36 and entering the reading unit 30. Therefore, adhesion of dust or the like to the reading surface 58 of the reading head 50 is reduced, and a decrease in reading accuracy is avoided. In the present embodiment, the portion of the recording paper cover 20 that functions as the document placing table 26 constitutes a document supporting member, and the top surfaces of a large number of ribs 89 formed there form the document supporting surface. Of.

At both ends of the head main body 52 of the reading head 50, as shown in FIG. 10, only one end is provided with an arm portion 90 extending in the longitudinal direction thereof and the arm portion 90. Is supported by a side wall 92 fixed to the lower cover 14 so as to be movable in the longitudinal direction. A protrusion 94 different from the arm 90 is provided at one end of the head main body 52, and one end of a connecting rod 96 is rotated via a bearing 98 at the protruding end of the protrusion 94. It is possible to install. The other end of the connecting rod 96 is rotatably connected to a crankshaft 102 that is rotated by a drive motor 100 via a bearing 104. When the crankshaft 102 is rotated, the read head 50 reciprocates in the longitudinal direction. Be moved.

An encoder 108 is attached to the output shaft of the drive motor 100. The encoder 108 is a thin disk provided with a plurality of slits radially, and a projector and a light receiver are provided with the encoder 108 sandwiched therebetween. By the rotation of the encoder 108 accompanying the rotation of the drive motor 100, the light emitted from the light emitter is received by the light receiver, and the light emitting elements 70R and 70Y are caused to emit light based on the light reception. The slits are not formed at equal intervals.

From the state where the distance between the shaft center of the drive motor 100 and the connecting portion between the protrusion 94 of the connecting rod 96 is maximum, while the drive motor 100 is rotated counterclockwise by 180 degrees in FIG. The head 50 is moved in the right direction (this direction is the forward direction), and is returned to its original position while being further rotated 180 degrees. Therefore, when the drive motor 100 rotates at a constant speed, the reading head 50 makes a motion in which the relationship between the moving distance and the time is represented by a sine curve, and the reading head 50 performs reading at equal intervals. Needs to control the light emission timing of the light emitting elements 70R and 70Y so that light is emitted each time the reading head 50 moves a distance equal to the pitch between the reading points defined at equal intervals. The slit spacing is so defined.

The read head 50 of the present embodiment is used in three modes: a black read mode in which red is also read as black, a red cut mode in which red is not read, and a black-red read mode in which black and red are read separately. You can When used in the black reading mode, only the yellow light emitting element 70Y emits light. In this case, according to the detection of one slit of the encoder 108, among the light emitting elements 70Y divided into eight groups, first, the light emitting element 70Y at the head in the traveling direction of the read head is made to emit light, and The portion irradiated by the light emitting fiber 56 attached to the light emitting element 70Y is read. After a very short time, the second light emitting element 70Y of each set is caused to emit light, and the light emitting elements 70Y of each set are sequentially caused to emit light, whereby the reading points every 4 mm are read. Then, when the reading head 50 moves 0.125 mm (one dot of the character) from the previous reading point, the next slit is detected, and accordingly, the first light emitting element 70Y of each set is caused to emit light again. . In this way, the light emitting elements 70Y of each group are sequentially caused to emit light and the read head 50 is moved, so that one light emitting element 70Y performs reading within a range of 4 mm, and one line is entirely read.

After reading one line, a document feed motor (not shown) is driven to rotate the large-diameter roller 46 and the document 36 is fed by one line. Then, while the read head 50 is moved in the opposite direction, the eight light emitting elements 70Y are sequentially caused to emit light, so that the next one line is read. The moving distance of the reading head 50 is larger than the distance (4 mm) between the light emitting elements 70Y (4.206 mm in this embodiment), and the moving distance of the reading head 50 reaches each end of the reading range. The document 36 is fed while the document 36 is further moved by a small distance, then inverted, and returned to the end of the reading range which is the reading start position. The eccentric amount of the crankshaft 102 is set to 2.103 mm so as to obtain such a moving distance of the reading head 50, and thus the motor 100 that drives the reading head 50 when the document 36 is fed is set. You do not have to stop the rotation.

The yellow light emitting element 70Y is caused to emit light when reading all the images recorded on the document 36 as black because the red image is read as black by the yellow light. Further, in the red cut mode in which a red image is not read, only the red light emitting element 70R emits light. A red image reflects red light to the same extent as a white background, so the red image is not read, only the black image is read.

Further, when the read head 50 is used in the black / red reading mode, both the yellow light emitting element 70Y and the red light emitting element 70R emit light. In this case, when the reading head 60 moves in the forward direction, only the yellow light emitting element 70Y emits light, and after reading one line, the document 36 is not fed and the reading head 50 is moved in the opposite direction. Only the red light emitting element 70R emits light. One line is read twice, and the read data when the yellow light emitting element 70Y emits light and the read data when the red light emitting element 70R emits light are processed as shown in Table 1 to determine black and red. . In this case, the binarization processing circuit 84 only outputs signals with and without an image, but when input to the computer, data representing each color is obtained based on the two types of signals. It is converted and stored in the read data memory of the RAM.

[0022]

[Table 1]

It is to be noted that the output based on the light emission of the yellow light emitting element 70Y is 0 and the output based on the light emission of the red light emitting element 70R is 1 when the image recorded in yellow on the original 36 is read. Since the yellow recording is not performed in the facsimile apparatus of this embodiment, it is determined to be white.

Next, the recording unit 32 will be described. As shown in FIG. 4, a recording paper holder 110, which is formed by forming a part of the frame 43 into a semi-cylindrical shape, is provided in a portion of the space 27 in the main body 12 covered by the recording paper cover 20. The thermosensitive recording paper 112 wound in a roll shape is rotatably accommodated in the recording paper holder 110. The thermosensitive recording paper 112 is guided forward by the guide portion 116 provided at the front end of the holder 110 and the paper pressing member 118 attached inside the recording paper cover 20. An end mark sensor 119 is attached below the guide portion 116 of the recording paper holder 110 as shown in FIG. A black mark is put on the back surface of the portion close to the end of the thermosensitive recording paper 112, and the sensor 119 detects the mark from the detection hole provided in the guide section 116 so that the computer does not have the thermosensitive recording paper 112. It is supposed to inform that it has become.

A platen 120 and a recording head 122 are provided on the front side of the holder 110. The platen 120 is rotatably supported by the lower cover 14 via a shaft 124, and is rotated by a recording paper feed motor (not shown). The recording head 122 is a line thermal type that simultaneously records one line by heat and is attached to the recording paper cover 20. The thermal recording paper 112 is set in the holder 110 with the recording paper cover 20 opened as shown by the chain double-dashed line in FIG. 4, and the front end of the recording paper cover 20 is pulled out onto the platen 120. When the recording head 122 is closed, the recording head 122 is brought into close contact with the recording paper 112 and recording is performed. The heat-sensitive recording paper 112 after recording is discharged from the gap between the recording paper cover 20 and the lower cover 14, but the edge facing the lower cover 14 of the recording paper cover 20 is formed into an acute angle. The cut portion 125 cuts the thermal recording paper 112. The operator can hold the discharged thermal recording paper 112 and pull it upward while keeping it in contact with the edge of the cut portion 125. At the time of cutting, the cutting chips fall down and wind up on the device body 12. Never rises.

The substrate 126 of the recording head 122 has a long shape, and a large number of heating elements are connected to each other. They are arranged at a pitch of 125 mm. A heat radiating plate 128 that radiates heat generated during recording is attached to the substrate 126, and a flexible cable 130 for driving the recording head is also connected to the substrate 126. The flexible cable 130 is protected by a cover 132.

The recording head 122 is connected to a power source at a connector 134 shown in FIG. 13, and is connected to a control circuit mainly composed of a computer at another connector 136, which is controlled by the computer. Then, an appropriate heating element is caused to generate heat and recording is performed. The recording head 122 constitutes the recording unit 32 together with the control circuit. The facsimile apparatus according to the present embodiment is designed to be capable of printing not only black but also two colors of black and red. A dedicated thermal recording paper 112 is set for each, and the computer is set to the black printing mode. It has a black-red print mode.

The thermal recording paper 112 for black printing has a coloring layer which develops black on heating on the surface of a base material. The thermal recording paper 112 for black red printing is provided on the surface of the base material. First, a coloring layer that develops red color is formed by heating, and a decoloring layer that reacts with the black coloring agent to erase black color by heating and a coloring layer that develops black color by heating are formed in that order. It is a thing. The color development temperature of the black color development layer is lower than the reaction temperature of the decolorization layer, and the color development temperature of the red color development layer is the highest. Therefore, in the case of printing only in black, it suffices to generate the heat energy necessary for coloring the black coloring layer in all of the heating elements that perform printing. And the heating element corresponding to the part printed in red generates heat energy necessary for coloring the black coloring layer, and then the heating element corresponding to the part printed in red receives the heat energy required for coloring the red coloring layer. It should be generated. The computer is provided with two kinds of recording modes in order to change the heating mode of the heating element as described above according to the type of the thermal recording paper 112.

As shown in FIG. 1, the switching of the recording mode of the computer is performed by a changeover switch 140 as an operating member. The changeover switch 140 is provided at a position adjacent to the end mark sensor 119 of the guide portion 116 of the recording paper holder 110, and is covered by the recording paper cover 20. As shown in FIG. 2, the changeover switch 140 can be changed over to two positions by linearly moving the knob 142. The changeover switch 140 is set to two changeover positions in a portion surrounding the changeover switch 140 of the lower cover 14. Corresponding portions are respectively displayed as "normal" for black printing and "red-black" for black-red printing, and the thermal recording paper 112 which the operator actually uses the changeover switch 140 while observing the display. It can be switched to the position corresponding to. Then, the recording mode of the computer is changed based on the signal emitted from the changeover switch 140. The type of the thermosensitive recording paper 112 may be displayed by a symbol or the like in addition to the characters.

In the facsimile device configured as described above, the reading unit 30 and the recording unit 32 are used independently, and the original is transmitted and received, and also used as a copying machine. In this case, first, the manuscript 36 is set on the manuscript table 26, and the manuscript 36 is read by the reading head 50. The data stored in the read data memory of the RAM of the computer is shuttle type data, but the data is converted into row data via the vertical / horizontal conversion gate array and stored in the recording data memory. Recording is performed on the thermosensitive recording paper 112 in the recording unit 32 based on the data. In this case, the desired type of thermal recording paper 112 is set in advance in the thermal paper holder 110, and the changeover switch 140 is switched to the side indicating the type of the thermal recording paper 112. Recording is performed according to the type.

As is clear from the above description, in the present embodiment, a dedicated changeover switch 140 is provided for changing over the recording mode of the recording section 32, and the changeover switch 140 is used for the telephone numeric buttons 22 and the like. Since it is provided on the lower cover 14 different from the original panel 18 provided with the transmission / reception operation button 24, it is not confused with the operation of those buttons 22 and 24, and the changeover switch 140 is not sensitive to heat. Since it is used only for selecting the recording paper 112, there is almost no risk of erroneous operation, and the operator can easily operate it.

Further, in the reading unit 30, the document pressing member 42 is attached to the openable / closable operation panel 18, and the reading head 50 is opened when the operation panel 18 is opened. And head cleaning can be easily performed. Further, since the recording head 122 is provided on the recording paper cover 20, it is possible to easily clean the recording head 122 by opening the recording paper cover 20 when paper dust or the like adheres. Moreover, if the opening 17 is divided into two parts by the operation panel 18 and the recording paper cover 20 like the main body 12 of the present facsimile machine, only the part necessary for the operation can be seen, so that the whole inside of the main body can be seen. There is no danger of being visible and giving the operator anxiety.

In the above embodiment, the operation member for switching the mode of the recording unit is a switch that linearly moves back and forth, but it may be a switch that switches by a plurality of touch switches or rotations. However, the present invention is not limited to this, and any device that can select the mode of the recording unit such as a variable resistor can be adopted. Further, in the above-described embodiment, the original 36 is read by the yellow and red lights, and the recording is performed in two modes. However, more colors are discriminated by using the blue light. In addition to the above, the present invention can be applied to a recording apparatus that can perform multicolor recording by using a thermosensitive recording paper having a multicolor coloring layer. Although not exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a perspective view showing a portion provided with a changeover switch of a facsimile apparatus including a document reading apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing switching of the changeover switch.

FIG. 3 is a perspective view showing an appearance of the facsimile device.

FIG. 4 is a side sectional view of the facsimile device.

FIG. 5 is a side view (partially sectioned) showing the vicinity of a reading head of the facsimile apparatus.

FIG. 6 is a front sectional view showing a part of a document placing table.

FIG. 7 is an exploded view schematically showing a reading head of the facsimile device.

FIG. 8 is a plan view showing a reading surface of the reading head.

FIG. 9 is a block diagram showing a configuration of a light receiving unit of the reading head.

FIG. 10 is a plan view (partial cross section) showing a moving mechanism of the reading head.

FIG. 11 is a diagram illustrating the principle of movement.

FIG. 12 is a side sectional view showing a main part of a recording unit of the facsimile device.

FIG. 13 is a rear view of the recording head.

[Explanation of symbols]

 10 Facsimile Machine 12 Main Body 17 Opening 18 Operation Panel 20 Recording Paper Cover 22 Numeric Buttons 24 Operation Buttons 26 Original Placement Table 30 Reading Section 32 Recording Section 34 Operation Panel Board 36 Original 40 Small Diameter Roller 42 Original Pressing Member 46 Large Diameter Roller 50 Reading Head 62, 64 spacer 89 rib

Continuation of front page (72) Koichi Mino 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Scope of utility model registration request] 1. A document reading apparatus including a reading unit for reading an original image displayed on a document while feeding the document in one direction, and a document supporting member for supporting the document on a document supporting surface and guiding the document to the reading unit. A document reading device characterized in that a plurality of ribs parallel to the document feeding direction are formed on the document supporting member, and the document supporting surface is formed by the top surfaces of the ribs. 2. The document reading apparatus according to claim 1, wherein the reading unit reads an original image displayed on a surface of the original that is in contact with the original supporting surface. 3. The document reading apparatus according to claim 1, wherein the total area of the top surfaces of the ribs is smaller than 1/2 of the area of the region where the ribs are formed. 4. The document reading device according to claim 1, wherein the rib is formed over the entire length of the document supporting member in the document feeding direction.