Reading device and recording device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2023-06-30
- Publication Date
- 2026-06-30
Smart Images
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Abstract
Description
[Technical field]
[0001] The present invention relates to a reading device. [Background technology]
[0002] Conventionally, there is known a reading device that is mounted on an image scanner, a multifunction printer, a copying machine, a facsimile machine, etc., and that reads an image recorded on an original. Such a reading device is also called a flatbed scanner, and includes a document glass on which an original can be placed, and a reading unit that is disposed directly below the document glass and capable of reciprocating within a plane parallel to the glass surface.
[0003] The reading unit is a contact image sensor (CIS). In a known reading device, an image sensor having a longitudinal direction, such as a hologram sensor, is mounted on a holding member. Patent Document 1 shows an example of the configuration of a reading device including an image sensor and a holding member. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2017-077932 A Summary of the Invention [Problem to be solved by the invention]
[0005] In the configuration of Patent Document 1, a rotation shaft is provided on the side surface of the housing of the image sensor in a direction substantially parallel to the longitudinal direction of the image sensor, and a holding member is provided to fit onto the shaft. When an original is read by the image sensor, a driving force is transmitted from a driving unit such as a motor to the reading unit, and the holding member is scanned along a guide provided in a direction perpendicular to the longitudinal direction of the image sensor.
[0006] Here, in order to read the document with high accuracy, it is important to keep the distance between the document and the image sensor constant during scanning. However, the guide portion along which the holding member scans is prone to deformation due to changes over time (creep deformation) and undulations in the molding. If the holding member is scanned on a guide portion that has undergone such deformation, the relative position between the image sensor and the holding member will change during document reading. In other words, the frictional force acting on the shaft portion of the image sensor described above tends to disrupt the dynamic balance around the center of gravity of the image sensor, causing the distance between the image sensor and the document to fluctuate during reading, which may result in a decrease in reading accuracy.
[0007] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a technique for improving the reading accuracy in a reading device. [Means for solving the problem]
[0008] The present invention employs the following configuration. a document table having a first surface facing the surface to be read of the document; an image sensor including a reading unit that reads the surface to be read through the document table and a frame portion that houses the reading unit; a holder having a biasing means for biasing the frame portion toward a second surface of the document table and for holding the image sensor so that the frame portion is in contact with the second surface; a guide member extending in a scanning direction of the image sensor and to which the holder is movably attached; having the holder has a contact portion that contacts the frame portion, the contact portion being located upstream of the image sensor in the scanning direction; The image sensor is a reading device characterized in that the frame portion moves in the scanning direction due to a force received from the contact portion, thereby reading the surface to be read by the reading means. Effect of the Invention
[0009] According to the present invention, it is possible to provide a technique for improving the reading accuracy in a reading device. [Brief description of the drawings]
[0010] [Figure 1] FIG. 1 is a perspective view of a multifunction peripheral including a reading device according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a partial cross-sectional view of an image reading apparatus according to an embodiment of the present invention. [Diagram 3] 1A and 1B are a top view and a cross-sectional view of a scanner unit according to the embodiment; [Figure 4] 1 is a rear view of the glass frame unit according to the embodiment; [Figure 5A] FIG. 2 is a perspective view of a reading unit according to the embodiment; [Figure 5B] FIG. 2 is a perspective view of a reading unit according to the embodiment; [Figure 5C] 1 is an exploded view of a reading unit according to an embodiment of the present invention; [Figure 6] FIG. 1 is a top view showing an internal configuration of an image reading device according to an embodiment of the present invention; [Figure 7] 1 is a cross-sectional view of an image sensor according to an embodiment of the present invention; [Figure 8] FIG. 2 is a block diagram showing an electric circuit configuration according to the present embodiment. [Figure 9] FIG. 3 is a cross-sectional view showing the main arrangement of a reading unit according to the embodiment; [Figure 10] FIG. 3 is a cross-sectional view showing the arrangement of each of the reading units according to the embodiment; [Figure 11] FIG. 3 is a cross-sectional view showing the arrangement of each of the reading units according to the embodiment; [Figure 12] FIG. 1 is a diagram showing an operation sequence when the power is turned on according to the present embodiment. [Figure 13] An operation sequence diagram during flatbed scanning according to the present embodiment. [Figure 14] An operation sequence diagram during ADF reading according to the present embodiment. [Figure 15] A distribution diagram of brightness levels of an image obtained by scanning a white sheet according to the present embodiment. [Figure 16] 1A and 1B are a top view and a cross-sectional view illustrating a configuration of a reading unit according to an embodiment of the present invention; [Figure 17] FIG. 2 is a perspective view of a reading unit according to the embodiment; [Figure 18] FIG. 2 is a cross-sectional view showing the configuration of a scanner unit and a document feeder according to the embodiment; [Figure 19] 1A and 1B are a top view and a cross-sectional view showing a configuration of a reading unit according to a conventional example; [Figure 20] 1 is a cross-sectional view showing the configuration of a reading unit according to this embodiment and a conventional example; [Figure 21] 1 is a cross-sectional view of a configuration of a scanner unit and a document feeder according to an embodiment and a conventional example; [Figure 22] FIG. 13 is a diagram showing a modified example of the reading unit according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in the embodiment are not intended to limit the scope of the present invention to those alone. Furthermore, the materials, shapes, etc. of the members once described in the following description are the same as those described initially, unless otherwise specified. Well-known or publicly known technologies in the relevant technical field can be applied to configurations and processes not particularly shown or described. Furthermore, duplicated descriptions may be omitted.
[0012] The reading device of the present invention can be applied to a flatbed scanner device, or a copying machine, facsimile, multifunction machine, etc., which is a combination of a flatbed scanner device and a printer device. In the following, an image reading device that imports an original image into a computer, etc. will be described as an example. Note that the same reference numerals indicate the same or corresponding parts throughout the drawings. X, Y, and Z are orthogonal to each other. The X direction indicates the cross direction of the image reading device, the Y direction is the depth direction, and the Z direction is the height direction.
[0013] [First embodiment] FIG. 1 is an external perspective view of a multifunction machine 1 according to the present invention. The multifunction machine 1 is a device in which an image reading device main body 100 is combined with a printing device 400, which is an inkjet printer. The printing device 400 is capable of printing (recording) an image read by the image reading device main body 100 using a recording means. The image reading device main body 100 of this embodiment is roughly composed of a scanner section 200 and an ADF section 300, which are image reading sections. FIG. 1 shows a state in which the ADF section 300 is opened to place a document on the scanner section 200. The axis PL of the rotation shaft when the ADF section 300 is opened and closed is indicated by a dashed line. Here, the ADF (Auto Document Feeder) refers to an automatic document transport device, and refers to a mechanism that automatically transports multiple documents to the reading section in sequence. The printing device 400 is not limited to an inkjet printer, and may be, for example, a laser printer (electrophotographic image forming device).
[0014] The configuration of the ADF unit 300 of the image reading device main body 100 will be described with reference to Fig. 2. Fig. 2 is a partial cross-sectional view of the image reading device main body 100 (scanner unit 200 and ADF unit 300) in the XZ plane when the ADF unit 300 is closed. In Fig. 2, a thick solid arrow indicates an original transport path 311, most of which passes through the ADF unit 300 and a part of which faces the scanner unit 200.
[0015] The ADF unit 300 includes an original placement platform 301 on which an original is placed, an original transport mechanism, and an original discharge unit 303. The configuration of the original transport mechanism will be described below, starting from the upstream side of the original transport. Here, the original transport mechanism refers to the entire paper transport mechanism from pickup roller 304 to discharge roller 309, which will be described below.
[0016] When the original 310 is first placed on the original placement table 301, it is transported to the separation roller 305 side by the pickup roller 304 of the original transport mechanism, and then transported one sheet at a time by the separation roller 305 and separation pad 306 to the downstream transport roller 307. Next, the original 310 is transported by the transport roller 307 to the downstream removable transport guide 203. When the original 310 passes through the removable transport guide 203, it is pressed by the white pressure plate 308 so that it adheres closely to the removable transport guide 203. At this time, the original 310 is read by the image sensor 206, which will be described later. The white pressure plate 308 has a size that covers the entire area of the image sensor 206 in the main scanning direction shown in FIG. 6.
[0017] Next, the original 310 that has passed through the removable transport guide 203 passes through an original size indicator member 205 downstream of the removable transport guide 203, and is discharged to the original discharge unit 303 by a downstream discharge roller 309. The removable transport guide 203 and the original size indicator member 205 are components of the scanner unit 200. Here, various original detection sensors (not shown) are arranged in the original transport mechanism unit, which detect the passage of the leading and trailing ends of the original, and the outputs are used to control the timing of reading by the image sensor 206.
[0018] There are two methods for reading the original 310 in the image reading device main body 100 of the present invention: a fixed original reading method (flatbed reading) and an original transport reading method (ADF reading). The fixed original reading method is a method in which the original 310 is fixed on the original platen glass 202 and the reading unit 207 is moved in the sub-scanning direction (X direction) to read the original 310. The transport reading method is a method in which the reading unit 207 is fixed at a predetermined position (ADF position) below the detachable transport guide 203 and the original 310 is transported by the ADF section 300 while being read. The reading unit 207 in the scanner section 200 in FIG. 2 is shown waiting at the ADF position to read the original 310 that is automatically transported by the ADF section 300 described above. There are.
[0019] The configuration of the scanner unit 200 of the image reading device main body 100 will be described below with reference to FIGS.
[0020] FIG. 3(a) is a top view of the scanner unit 200 when the ADF unit 300 is removed from the image reading device main body 100, and shows the entire glass frame unit 201. This glass frame unit 201 is composed of a document table glass 202 on which a document is placed, and a glass frame 204 that holds the above-mentioned removable transport guide 203 for reading an automatically transported document. The glass frame 204 also has the above-mentioned document size indicator member 205 and document abutment reference 226 between the document table glass 202 and the removable transport guide 203. Of the two sides of the document table glass 202 that serves as a document table, the surface that faces the surface to be read of the document and that is the upper side in normal installation is the upper surface, which is also called the first surface. The surface opposite to the upper surface is the lower surface, which is also called the second surface.
[0021] Fig. 3(b) is a cross section taken along line AA in Fig. 3(a). Fig. 3(c) is a cross section taken along line BB in Fig. 3(a), showing a cross section in the main scanning direction (Y direction) of the reading unit 207. Fig. 3(d) is an enlarged view of a portion C around the document size indicator member 205 in the glass frame unit 201 in Fig. 3(b).
[0022] In the figure, a white sheet 224 is disposed on the document placement surface side of document table glass 202. In this cross-sectional view, white area 224W and black area 224B are simply shown, but in reality, the structure is as described later in FIG.
[0023] Fig. 4 is a rear view of the glass frame unit 201 in Fig. 3(a), and shows a part of the white sheet 224. The document table glass 202 abuts against two glass frame abutment portions 228 of the glass frame 204, and the position in the X direction is determined. In the viewing direction of this figure, the white sheet 224 is disposed on the rear side of the document table glass 202 (the side on the same surface as the document placement surface).
[0024] In Fig. 4, the X-direction position of white sheet 224 is disposed between glass frame abutment portion 228 and stationary document reading area 237. White sheet 224 also integrally includes white area 224W for performing shading correction of the image sensor and black area 224B which is the sub-scanning direction reference position of the image sensor. In order to perform shading processing, white sheet 224 has a size that covers the entire area of the image sensor in the main scanning direction. Within white sheet 224, the sub-scanning direction (X-direction) position of black area 224B is formed closer to stationary document reading area 237 than white area 224W. The black area 224B and the main scanning direction area will be described later with reference to Fig. 6.
[0025] 5A and 5B are perspective views of the reading unit 207. FIG. 5C is an exploded view of the reading unit 207. The reading unit 207 is composed of an image sensor 206, a sensor holder 217, a slider 218, and a drive transmission part 239 that transmits a driving force to the reading unit 207. The image sensor 206 has a longitudinal direction and a lateral direction, and the longitudinal direction is also called the main scanning direction. The reading unit 207 is scanned in a sub-scanning direction (scanning direction) that intersects (typically perpendicular to) the main scanning direction.
[0026] At both ends of the image sensor 206 in the main scanning direction, roller units 211 and 212 are disposed to ensure the focal distance with respect to the document to be read. At both ends of the roller units 211 and 212 in the sub-scanning direction, rollers 213 and 214, and rollers 215 and 216 are rotatably disposed. In addition, between the image sensor 206 and a sensor holder 217 as a holder, A pressure spring 232, which is a biasing means, is disposed to constantly press the image sensor 206 against the rear surface of the platen glass 202. Therefore, when the reading unit 207 moves in the sub-scanning direction (X direction), these roller pairs roll on the rear surface of the platen glass 202 (not shown).
[0027] 6 is a diagram showing the overall internal configuration of the scanner unit 200 with the glass frame unit 201 removed from the top view shown in FIG. 3(a). The arrangement and configuration of the reading unit 207 and the base frame 223 will be described with reference to FIG.
[0028] A guide rail 221 is disposed in the approximate center of the base frame 223 in the Y direction as a guide member with its longitudinal direction as the sub-scanning direction. The slider 218 of the reading unit 207 described above is attached to the guide rail 221 so as to be slidable in the sub-scanning direction (X direction). When the reading unit 207 scans, the motor 220 is driven as a driving means to move the belt 222. The reading unit 207 is then driven through a drive transmission unit 239 to which the belt 222 is connected, and scans back and forth along the guide rail 221. Note that this embodiment is a belt-driven type in which a driving unit is disposed in the base frame 223 and its driving force is transmitted by the belt 222, but the present invention can also be applied to a self-propelled reading unit in which a driving means is disposed in the reading unit 207.
[0029] The electrical configuration of image sensor 206 will be described below with reference to Figs. 7 and 8. Fig. 7 is a cross-sectional view of image sensor 206. Inside image sensor 206, LEDs 102 that are light-emitting elements of three colors, RGB, a rod lens array 209 in which rod lenses are arranged, and a light-receiving element 101 are built in. Light irradiated from LEDs 102 onto an original passes through original platen glass 202 and is reflected by the original surface. This reflected light passes through rod lens array 209 to form an image on light-receiving element 101. Image sensor 206 sequentially switches on and off three color LEDs 102, and performs color separation reading by reading the reflected light from the original for each color.
[0030] FIG. 8 is a block diagram showing the configuration of a control circuit of the reading unit in this embodiment. The circuit operation of this embodiment will be described below. In FIG. 8, the image sensor 206 is a sensor in which three color LEDs 102, which are light sources, are integrated. This image sensor 206 is moved in the scanning direction under the platen glass. At the same time, the LEDs 102 of each color are switched and turned on for each line by the LED drive circuit 103, so that it is possible to read a color image in RGB line sequence. The amplifier (AMP) 104 amplifies the signal output from the image sensor 206. The A / D converter 105 performs A / D conversion of the amplified output of the amplifier 104 to obtain, for example, an 8-bit digital output.
[0031] The shading RAM 106 stores data for shading correction obtained by reading the white region 224W (see FIG. 7) for the above-mentioned shading processing and processing the data. The shading correction circuit 107 performs shading correction of the image data read by the image sensor 206 based on the data in the shading RAM 106. The peak detection circuit 108 is a circuit that detects the peak value in the read image data for each line, and is used to detect the reference position of the reading unit 207 (see FIG. 6). The gamma conversion circuit 109 performs gamma conversion of the read image data in accordance with a gamma curve preset by a host computer, which will be described later.
[0032] The buffer RAM 110 is a memory that temporarily stores image data in order to synchronize the timing of the actual reading operation with the communication with the host computer. The packing / buffer RAM control circuit 111 writes the data to the buffer RAM 110 after performing packing processing according to the image output mode preset by the host computer. and a process of transferring and outputting image data from the buffer RAM 110 to the interface circuit 112. Note that the image main output modes include binary, 4-bit multi-value, 8-bit multi-value, 24-bit multi-value, and the like.
[0033] The interface circuit (transfer means) 112 receives control signals and outputs image signals between it and an external device 113. The external device 113 is a device such as a personal computer that serves as a host device (computer) for the image reading device.
[0034] The CPU 115 has a ROM 115a storing processing procedures and a working RAM 115b, and is, for example, a microcomputer type CPU that controls each part according to the procedures of the program stored in the ROM 115a. The CPU 115 controls the rotation direction, rotation speed, and rotation amount of the motor 220 (see FIG. 6) by reading slit information of a code wheel 241 rotatably fixed on the same axis of the motor with an encoder 242. That is, it controls the moving direction, moving speed, distance, etc. of the reading unit 207 (see FIG. 6). The OSC (oscillator) 116 is, for example, an oscillator such as a crystal oscillator. The timing signal generating circuit 114 divides the output of the OSC 116 according to the setting of the CPU 115 to generate various timing signals that are the basis of operation.
[0035] In this embodiment, the boundary between the black area 224B (see FIG. 7) and the white area 224W (see FIG. 7) serves as a reference mark 224S for image reading by the image sensor 206. The reference mark 224S read by the image sensor 206 is detected by an encoder and stored in the RAM 115b in the CPU 115 as a reference position.
[0036] The CPU 115 functions as a detection means for detecting this reference mark 224S, and as a control means for determining a reference position of the image sensor 206 based on the detected reference mark 224S and starting image readout. The CPU 115 performs initialization movement of the image sensor 206 before image readout when the power is turned on, and movement of the image sensor 206 after image readout, based on the reference position determined by the reference mark 224S detected in the sub-scanning direction.
[0037] Next, the operation of the reading unit 207 will be described with reference to Figures 9, 10, 11, 12, 13, and 14. Figures 9 to 11 are partial cross-sectional views related to the operation. Figures 12 to 14 are flow charts showing the operation sequence.
[0038] 9 indicate the optical centers (indicated by dashed lines in FIG. 9) of the rod lens array 209 (see FIG. 7) of the image sensor 206 at various times. That is, a position before power-on, b an initialization position, c a reference position detection position, These are the home position d (shading start position), the shading end position e, the document image reading start position f, the ADF reading position g, and the transport guide detection position h. In the drawing, the reference position detection position c is simply shown as the white area 224W and the black area 224B in the cross-sectional view, but in reality it is configured as described in FIG.
[0039] Before power is turned on, the reading unit 207 is in position a shown in Fig. 9. However, after power is turned on, the next initialization operation is performed, so the sub-scanning position of the reading unit 207 at this time may be any position.
[0040] Immediately after power is turned on, there is no position information in the device memory, so the CPU 115 always moves the reading unit 207 in the return direction. Then, the CPU 115 moves the reading unit 207 until the slider abutment portion 231 of the slider 218 abuts against the base frame abutment portion 230 of the base frame 223 under the platen glass 202. (Initialization Operation) (FIG. 12: Step S101)
[0041] After hitting the abutment, the reading unit 207 cannot move any further, so the load on the motor that drives the reading unit 207 increases, and the current supplied to the motor also increases proportionally. A threshold value is set for the current value using the characteristics of this motor, and when the current value reaches the threshold value, the CPU 115 determines that the reading unit 207 has hit the base frame abutment portion 230 of the base frame 223. The reading unit 207 at this time is at the initialization position b (FIG. 10(a)).
[0042] Next, CPU 115 moves reading unit 207 in the scanning direction to detect reference position c at the boundary between white area 224W and black area 224B on white sheet 224. FIG. 10(b) shows the state where image sensor 206 has reached a position to read the reference mark. When image sensor 206 detects the reference mark (boundary position between white area 224W and black area 224B), CPU 115 sets the reference mark detection position as reference position c based on the encoder signal. (FIG. 12: Step S102)
[0043] The CPU 115 stores the reference position c detected during the movement in the scanning direction in the RAM 115b as a reference for flatbed reading (FIG. 12: step S103).
[0044] Next, the CPU 115 moves the reading unit 207 from the reference position c in the return direction by a specified amount, and makes it reach the home position d (FIG. 12: step S104). In this embodiment, this home position d is set as the shading start position (FIG. 10(c)).
[0045] Up to this point, after power is turned on, the CPU 115 performs the initialization operation of the image sensor 206, detects the reference position c, and moves to the home position d.
[0046] Next, the operation of the reading unit 207 during flatbed reading will be described. Before reading an image, the CPU 115 instructs the reading unit 207 to perform shading processing of the image sensor 206. The white area 224W is read in the scanning direction from the home position d, which is the shading start position, to a predetermined length (shading end position e) at a predetermined reading resolution, and the shading processing ends (FIG. 11(a)) (FIG. 13: step S201).
[0047] After shading is completed, CPU 115 moves reading unit 207 to home position d based on reference position c stored in RAM 115b. Then, after reading unit 207 moves a specified distance in the scanning direction and the speed in the sub-scanning direction reaches a stable reading speed, image reading is started from document image reading start position f (FIG. 11(b)) (FIG. 13: steps S202 to S203).
[0048] According to the above configuration, the reading position accuracy of the image sensor 206 is improved, and the variation in the image sensor operating area is reduced. After the reading operation is completed, the CPU 115 moves the reading unit 207 in the sub-scanning direction toward the reference position c.
[0049] After the moving operation is completed, the CPU 115 detects the reference position again in the scanning direction (FIG. 13: step S204). Then, the CPU 115 stores the reference position c in the RAM 115b (FIG. 13: step S205). Then, the CPU 115 moves the reading unit 207 to the home position d (FIG. 13: step S206). This completes the flatbed reading operation.
[0050] Next, the operation of the reading unit 207 during ADF reading will be described. The same step number is assigned to the process. When ADF reading is started, the CPU 115 moves the reading unit 207 from the home position d to the conveying guide detection position h (FIG. 11(d)) (FIG. 14: step S401)
[0051] The reading unit 207 moves to a transport guide detection position h and stops there, where the image sensor 206 reads the entire area in the longitudinal direction of the image sensor 206. Using the read detection pattern, the open / closed state of the ADF and the transport guide 203 are detected.
[0052] If the image sensor 206 fails to detect the transport guide 203 (FIG. 14: step S402=No), the CPU 115 displays information indicating that the transport guide was not detected normally (transport guide detection error) (FIG. 14: step S403). In S403, instead of simply notifying the error, a notification may be given to the user to check whether the transport guide 203 is attached in the specified position. The method of notification is not limited to a display on the display screen, but may be notification via the external device 113, or notification using sound, vibration, etc. Thereafter, the CPU 115 moves the reading unit 207 to the home position d and ends the operation. (FIG. 14: step S306)
[0053] On the other hand, if the image sensor 206 succeeds in detecting the transport guide 203 (FIG. 14: step S402=Yes), the reading unit 207 performs shading processing of the image sensor 206 in response to an instruction from the CPU 115. (FIG. 14: step S201)
[0054] After that, the CPU 115 moves the reading unit 207 from the home position d in the scan direction by a certain amount and then moves it in the return direction. Then, when the image sensor 206 detects a reference mark (the boundary position between the white area 224W and the black area 224B), the CPU 115 sets the reference mark detection position as a reference position c' based on the encoder signal (FIG. 10(b)) (FIG. 14: step S301). The CPU 115 stores the reference position c' when moving in the return direction in the RAM 115b as a reference for ADF reading (FIG. 14: step S302). Then, the CPU 115 moves the reading unit 207 from the reference position c' in the return direction by a specified amount and stops it at the ADF reading position g (FIG. 11(c)) (FIG. 14: step S303).
[0055] With the above configuration, the return direction detection reference position c' is used during return direction movement, improving positional accuracy during return direction movement, reducing variation in the operating area of the image sensor 206, and enabling improved accuracy during ADF reading.
[0056] When ADF reading is completed, CPU 115 moves reading unit 207 in the scanning direction and detects reference position c again (FIG. 10(b)) (FIG. 14: step S304). Then CPU 115 stores reference position c in RAM 115b (FIG. 14: step S305). Then CPU 115 moves reading unit 207 to home position d (FIG. 14: step S306).
[0057] In this configuration, by using the reference position c when reading with the flatbed and the reference position c' when reading with the ADF, it is possible to move to the desired position accurately without being affected by backlash in the drive train. As a result, high-precision reading is possible at each reading.
[0058] Next, the operation when flatbed reading and ADF reading are performed multiple times will be described. When flatbed reading is performed after flatbed reading, the operation of the flow in FIG. 13 is performed, and then the operation of the flow in FIG. 13 is performed again. When ADF reading is performed after flatbed reading, the operation of the flow in FIG. 13 is performed, and then the operation of the flow in FIG. 14 is performed. The work will be carried out.
[0059] When flatbed reading is performed after ADF reading, the operation of the flow in Fig. 14 is performed, and then the operation of the flow in Fig. 13 is performed. When ADF reading is performed after ADF reading, the operation of the flow in Fig. 14 is performed, and then the operation of the flow in Fig. 14 is performed again. Note that the reference position c and the reference position c' stored in RAM 115b are overwritten and held each time the type of reading is switched.
[0060] Below, we will explain the relationship between the white areas 224W and black areas 224B in the white sheet 224 and the illumination direction in the image sensor 206. Fig. 15 is a graph showing the brightness levels of an image read by the image sensor 206 (see Fig. 7) of the white sheet 224. Fig. 15 shows the distribution of brightness levels in the sub-scanning direction corresponding to the E-E cross section in Fig. 4. The vertical axis shows the brightness level and the horizontal axis shows the distance in the sub-scanning direction.
[0061] The solid line graph shows the brightness level when irradiated from the direction of solid line arrow 235 in Fig. 7, and the dashed line graph shows the brightness level when irradiated from the direction of dashed line arrow 236 in Fig. 7. In Fig. 7, light guide 208 that irradiates light in the direction of solid line arrow 235 is disposed on the white region 224W side in the sub-scanning direction with respect to rod lens array 209. The light is irradiated from the white region 224W side toward the black region 224B side in the figure.
[0062] Next, the configuration and features of the reading unit 207 as the reading means in this embodiment will be described. Fig. 16(a) is a top view of the reading unit 207 in this embodiment. Fig. 16(b) is a cross-sectional view showing the image sensor 206, the sensor holder 217 which forms a frame portion, and the A-A' cross section of the reading unit 207. The reading unit 207 is composed of the image sensor 206, the sensor holder 217, and a slider 218 (see Figs. 5A to 5C).
[0063] The image sensor 206 includes a sensor frame 240. Inside the sensor frame 240, a light guide 208 and a rod lens array 209 are arranged in this order from the upstream side in the scanning direction. An electric board 210 on which a light receiving element is mounted is arranged below the rod lens array 209 in the Z direction. Two protrusions 219 are provided on the end face of the sensor frame 240 on the upstream side in the scanning direction and on both ends in the main scanning direction, which is the longitudinal direction of the image sensor 206. The protrusions 219 are located on the upstream side in the scanning direction as viewed from the light guide 208 and the rod lens array 209 described above. The protrusions 219 are arranged in contact with a contact portion 411 on the inner wall of the sensor holder 217 on the upstream side in the scanning direction.
[0064] Scanning during reading will be described with reference to Figs. 6 and 16. When CPU 115 inputs a drive command to motor 220, belt 222 moves with the motor drive, and sensor holder 217 is scanned through drive transmission unit 239 (not shown) to which belt 222 is connected. At this time, image sensor 206, which is in contact with sensor holder 217 through contact unit 411, is also scanned together with sensor holder 217. Thus, in this embodiment, a drive force is transmitted from sensor holder 217 to image sensor 206 through protrusion 219. Note that, although two protrusions 219 are provided in this embodiment, a plurality of protrusions may be provided, and the number is not limited to two.
[0065] 17 is a perspective view of the image sensor 206 as viewed from the upstream side in the scanning direction. In this embodiment, the two protrusions 219 are disposed on a surface 240a of the sensor frame 240 perpendicular to the scanning direction, and have a protruding shape that protrudes in the opposite direction to the scanning direction. The positions of the two protrusions 219 in the Z direction are within the height of the inner wall of the sensor holder 217 with which the contact portion 411 comes into contact. It is structured to fit within this.
[0066] 18 is a diagram showing the main cross section of the scanner unit 200 and the ADF unit 300 on the left side of the device. Here, the reading unit 207 is located at the ADF reading position g. As described above, the sensor holder 217 receives power from the motor 220 (not shown) and can reciprocate in the scan direction and return direction. When scanning in the scan direction, the sensor holder 217 transmits a driving force to the image sensor 206 via a contact portion 411 with the protrusion 219 of the sensor frame 240, thereby moving the image sensor 206 in the scan direction.
[0067] Next, the features of the configuration of this embodiment will be described by comparing the reading unit of this embodiment with that of the conventional example. FIG. 19(a) is a top view of the reading unit 607 of the conventional example. FIG. 19(b) is a cross-sectional view showing the A-A' section of the image sensor 606, the sensor holder 617, and the reading unit 607. The reading unit 607 is composed of the image sensor 606, the sensor holder 617, and a slider (see FIG. 5B) as in this embodiment. The image sensor 606 includes a sensor frame 640. Inside the sensor frame 640, a rod lens array 609 and a light guide 608 are arranged in this order from the upstream side in the scanning direction. An electric board 610 on which a light receiving element is mounted is arranged below the rod lens array 609 in the Z direction. The sensor frame 640 also has a rib 614 extending in the Y direction perpendicular to the scanning direction on the downstream side of the light guide 608 in the scanning direction, and is configured to have a driving force transmission section that transmits power in the scanning direction and the return direction at the contact point where it abuts against the sensor holder 617.
[0068] FIG. 20 shows cross-sectional views of respective reading units for comparison between the present embodiment and the conventional example. FIG. 20(a) is a cross-sectional view of the reading unit 207 in the present embodiment. In the figure, A1 indicates the distance in the scanning direction from the rod lens array 209 to the right end face of the sensor holder 217, and M1 indicates the distance between the centroid position G of the image sensor 206 and the contact portion 411. FIG. 20(b) is a cross-sectional view of the reading unit 607 in the conventional example. In the figure, B1 indicates the distance in the scanning direction from the rod lens array 609 to the right end face of the sensor holder 617, and N1 indicates the distance between the centroid position G of the image sensor 606 and the contact portion 611.
[0069] Here, in FIG. 20(a), the components within the distance A1 are the rod lens array 209, the end portion of the sensor holder 217, and the side wall portion 240b therebetween. The side wall portion 240b is the side wall of the sensor frame 240 of the image sensor 206.
[0070] On the other hand, in FIG. 20(b), the components within the distance B1 are the rod lens array 609, the end portion of the sensor holder 617, and a group of components therebetween. In this group of components, in addition to the side wall portion 640b, there are a light guide 608 and a driving force transmission portion (the contact portion 611 in this figure corresponds to this) that transmits the driving force to the image sensor 606 with a rib 614. Therefore, the distance A1 in the present embodiment is smaller than the distance B1 in the conventional example.
[0071] Also, in the conventional example, the distance N1 is configured via the sensor holder 617 between the sensor frame 640 and the contact portion 611. In contrast, in the present embodiment, no other components are interposed between the sensor frame 240 and the contact portion 411. Therefore, the distance M1 is smaller than the distance N1. That is, when comparing the reading units of the present embodiment and the conventional example, the relationships A1 < B1 and M1 < N1 hold.
[0072] In each of the present embodiment and the conventional example, the image sensors (206, 606) are biased toward the back side of a document table glass 202 (not shown) by pressing springs (232, 632) as biasing means, and the focal length with respect to a document placed via each roller unit (211, 511) is maintained. Then, as described above, when an input of drive is received from the motor 220, the sensor holders (217, 617) slide on a guide rail 221 (not shown) according to the input, and scan the image sensors (206, 606) via the contact portions 411, 611.
[0073] However, the guide rail 221 is likely to vary in the Z direction due to undulations in molding or changes over time (creep deformation), etc., and accordingly, the position of the sensor holders (217, 617) in the Z direction varies. On the other hand, since the image sensors (206, 606) are biased and maintained toward the back side of the document table glass 202 (not shown) by the pressing springs (232, 632), as a result, the relative positions of the image sensors (206, 606) and the sensor holders (217, 617) change. At this time, since a frictional force associated with the change in the relative position acts on the contact portions 411, 611, a rotational moment acts on the center-of-gravity position G of the image sensors (206, 606), and there is a risk that the posture of the image sensors (206, 606) collapses and the focal length changes, leading to a decrease in the reading accuracy.
[0074] This rotational moment is determined by the frictional force acting on the contact portions 411, 611 and the distances (M1, N1) between the center-of-gravity position G and the contact portions. The larger the rotational moment, the more likely the focal length is to change. In the present embodiment, by setting M1 < N1, the rotational moment as a disturbance can be suppressed to be smaller than before. As a result, the reading accuracy can be improved. Also, in the present embodiment, the contact portions 411, 611 are formed in a protruding shape, but they may also be formed in a concave shape or a flat shape.
[0075] Fig. 22 shows a modified example in which the contact portion has a concave shape. Concave portion 919 shown in the plan view of Fig. 22(a) and the CC' cross-sectional view of Fig. 22(b) is a portion that is provided on the upstream side of image sensor 206 in the scanning direction in place of protrusion 219 and has a shape recessed from surface 240a. Concave portion 919 may be provided on both ends of image sensor 206 in the longitudinal direction, but the number and positions are not limited to this.
[0076] 22(c), a convex portion 911 is provided in a portion of sensor holder 217 facing concave portion 919. During scanning, convex portion 911 comes into contact with concave portion 919 and transmits driving force from motor 220 to image sensor 206. Even if the relative positions of image sensor 206 and sensor holder 217 in the Z direction fluctuate due to deformation of the guide portion in the Z direction, the gaps above and below convex portion 911 in the Z direction provide play, thereby suppressing the influence of the up and down movement of image sensor 206.
[0077] FIG. 21 shows the main cross section of the right side of the scanner unit and the ADF unit for comparison between this embodiment and the conventional example. FIG. 21(a) is a cross section of the scanner unit 200 when the reading unit 207 reaches the end position (hereinafter, the scan end position) of the reading scan of the maximum readable size document (not shown) placed on the document glass 202 in this embodiment. A2 in the figure indicates the distance between the rod lens array 209 and the right end face of the scanner unit 200. A3 in the figure indicates the distance from the right end face of the sensor holder 217 to the inner wall of the right end of the scanner unit 200. This A3 is a clearance set due to mechanical variations. In this embodiment, the right end of the scanner unit 200 coincides with the right end of the device body.
[0078] FIG. 21(b) is a cross-sectional view of the scanner unit 600 when the reading unit 607 is located at the scan end position in the conventional example. In the figure, B2 indicates the distance between the rod lens array 609 and the right end face of the scanner unit 600. In the figure, B3 indicates the distance from the right end face of the sensor holder 617 to the inner wall of the right end portion of the scanner unit 600. This B3 is a clearance set due to mechanical variations. In the conventional example, the right end portion of the scanner unit 600 coincides with the right end of the apparatus main body.
[0079] Here, the distance A3 and the distance B3 are the same distance due to the same clearance caused by the same mechanical variations. Also, the difference between the distance A2 and the distance B2 is the same as the difference between the aforementioned distance A1 and the distance B1. Therefore, it is clear that the distance A2 in the present embodiment is shorter than the distance B2 in the conventional example. Thus, in the configuration of the present embodiment, since A2 < B2 holds, downsizing of the entire apparatus can be achieved as compared with the conventional example. The above description relates to an apparatus having a scanner unit and an ADF unit, but the same effect can also be obtained for an apparatus configured with a scanner unit not equipped with an ADF unit.
[0080] As described above, in the conventional reading apparatus, when the guide rail for guiding the carriage for the image sensor is deformed in the vertical direction of the apparatus due to undulations or creep deformation in molding, the carriage position also changes following it. As a result, frictional force is generated by the sliding of the contact portion, and the image sensor is likely to separate from the back surface of the document table glass, which is a problem of deterioration in reading accuracy. On the other hand, according to the configuration of the present embodiment, it becomes possible to transmit the driving force at a position closer to the center of gravity of the image sensor, and by suppressing the variation in the distance between the image sensor and the document, it becomes possible to improve the reading accuracy.
[0081] [Configuration 1] A document table having a first surface facing the surface of the document to be read, Reading means for reading the surface to be read through the document table, and a frame portion for housing the reading means, an image sensor comprising: a holder having a biasing means for biasing the frame portion toward a second surface of the document table and for holding the image sensor so that the frame portion is in contact with the second surface; a guide member extending in a scanning direction of the image sensor and to which the holder is movably attached; having the holder has a contact portion that contacts the frame portion, the contact portion being located upstream of the image sensor in the scanning direction; The image sensor is characterized in that the frame portion moves in the scanning direction due to a force received from the contact portion, thereby causing the reading means to read the surface to be read. [Configuration 2] The contact portion is in contact with the frame portion such that a contact position with respect to the frame portion can be displaced in a direction intersecting with a second surface of the document table. 2. The reading device according to configuration 1, [Configuration 3] the contact portion is a surface intersecting the scanning direction, The frame portion has a protrusion that protrudes in a direction opposite to the scanning direction and has a tip that comes into contact with the surface. 3. The reading device according to configuration 2, [Configuration 4] the contact portion is a protrusion that protrudes in the scanning direction, The frame portion has a surface that intersects with the scanning direction and that is in contact with the tip of the protrusion portion. 3. The reading device according to configuration 2, [Configuration 5] the frame portion has a recess that is recessed in the scanning direction on a side surface intersecting the scanning direction on an upstream side of the scanning direction, the surface is a bottom surface of the recess, The width of the recess in at least a direction intersecting with the second surface of the document table is set to be smaller than the width of the recess in accordance with the relative movement between the image sensor and the holder in the direction intersecting with the second surface of the document table. The width allows the displacement of the contact position of the protrusion with respect to the bottom surface. 5. The reading device according to configuration 4. [Configuration 6] The contact portion has a plurality of contact positions with respect to the frame portion, the contact positions being different in a longitudinal direction intersecting with the scanning direction. 6. The reading device according to any one of configurations 1 to 5, [Configuration 7] the contact portion being a first contact portion, and a portion of the frame portion that comes into contact with the first contact portion being a first contacted portion; the first contact portion and the first contacted portion are disposed on a first side in a longitudinal direction intersecting the scanning direction, the holder has a second contact portion that is located upstream of the image sensor in the scanning direction and that comes into contact with the frame portion in the scanning direction; the frame portion has a second contacted portion with which the second contact portion comes into contact, the second contacted portion being disposed on an upstream side in the scanning direction; the second contact portion and the second contacted portion are disposed on a second side opposite to the first side in the longitudinal direction, The reading device described in any one of configurations 1 to 5, characterized in that the image sensor moves in the scanning direction while sliding against the second surface of the document table due to the force received by the first contact portion from the first contact portion and the force received by the second contact portion from the second contact portion. [Configuration 8] 8. The reading device according to any one of configurations 1 to 7, wherein the reading means includes a light emitting element, an imaging lens, and a light receiving element. [Configuration 9] 9. The reading device according to configuration 8, wherein the contact portion, the light emitting element, and the imaging lens are arranged in this order from upstream to downstream in the scanning direction. [Configuration 10] 10. The reading device according to configuration 9, wherein the light receiving element is disposed on the opposite side of the imaging lens from the document table. [Configuration 11] The reading device described in any one of configurations 1 to 10, characterized in that the urging means is a spring that is compressed in a direction perpendicular to the second surface between a first surface along the scanning direction on the opposite side of the frame portion that contacts the second surface of the document table, and a second surface of the holder along the scanning direction that faces the first surface in a direction perpendicular to the second surface. [Configuration 12] 2. A recording apparatus comprising the reading device according to claim 1, wherein the image read by the reading means is recorded by a recording means. [Explanation of symbols]
[0082] 100: Image reading device main body, 200: Scanner unit, 202: Original platen glass, 204: Glass frame, 206: Image sensor, 207: Reading unit, 217: Sensor holder, 219: Protrusion, 221: Guide rail, 411: Contact unit
Claims
1. A document tray having a first surface where the reading surface of the document faces the opposite surface, An image sensor comprising: a reading means for reading the surface to be read via the document glass; and a frame portion for housing the reading means; A holder having a biasing means for biasing the frame portion toward the second surface of the document tray, and holding the image sensor so as to bring the frame portion into contact with the second surface, A guide member extending in the scanning direction of the image sensor and to which the holder is movably mounted, It has, The holder has a contact portion that contacts the frame portion on the upstream side in the scanning direction relative to the image sensor, The image sensor reads the surface to be read by the reading means as the frame portion moves in the scanning direction due to the force received from the contact portion. The contact portion is in contact with the frame portion such that its contact position with the frame portion can be displaced in a direction intersecting the second surface of the document table. A reading device characterized by the following.
2. The contact portion is a surface that intersects the scanning direction, The frame portion has a projection that protrudes in the direction opposite to the scanning direction, and the surface contacts the tip of the projection. The reading device according to feature 1.
3. The contact portion is a projection that protrudes in the scanning direction, The frame portion has a surface that intersects the scanning direction and to which the tip of the projection makes contact. The reading device according to feature 1.
4. The frame portion has a recess that is recessed in the scanning direction on the side surface that intersects the scanning direction on the upstream side of the scanning direction, The aforementioned surface is the bottom surface of the recess, The width of the recess, at least in the direction intersecting the second surface of the document platen, is such that the relative movement between the image sensor and the holder in the direction intersecting the second surface of the document platen is such that This width allows for the resulting displacement of the contact position of the projection with respect to the bottom surface. The reading device according to feature 3.
5. The contact portion has multiple contact positions with respect to the frame portion that are located at different positions in the longitudinal direction intersecting the scanning direction. The reading device according to feature 1.
6. The contact portion is designated as the first contact portion, and the portion of the frame that contacts the first contact portion is designated as the first contacted portion. The first contact portion and the first contacted portion are arranged on the first side in the longitudinal direction intersecting the scanning direction, The holder has a second contact portion that contacts the frame portion in the scanning direction on the upstream side of the scanning direction relative to the image sensor, The frame portion has a second contacted portion that the second contact portion contacts on the upstream side in the scanning direction, The second contact portion and the second contacted portion are arranged on the second side opposite to the first side in the longitudinal direction. The reading device according to claim 1, characterized in that the image sensor moves in the scanning direction while sliding with respect to the second surface of the document table due to the force that the first contacted portion receives from the first contacted portion and the force that the second contacted portion receives from the second contacted portion.
7. The reading device according to claim 1, characterized in that the reading means includes a light-emitting element, an imaging lens, and a light-receiving element.
8. The reading device according to claim 7, characterized in that the contact portion, the light-emitting element, and the imaging lens are arranged in this order from upstream to downstream in the scanning direction.
9. The reading device according to claim 8, characterized in that the light-receiving element is arranged on the opposite side from the document table with respect to the imaging lens.
10. The reading device according to any one of claims 1 to 9, characterized in that the biasing means is a spring provided between the first surface of the frame portion that is in contact with the second surface of the document platen and is aligned with the scanning direction, and the second surface of the holder that is aligned with the scanning direction and is opposed to the first surface in a direction perpendicular to the second surface, and is compressed in a direction perpendicular to the second surface.
11. A recording device comprising a reading device as described in claim 1, characterized in that an image read by the reading means is recorded by a recording means.