JP6245446B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a reading unit having a carriage that is reciprocally movable in a sub-scanning direction orthogonal to a main scanning direction.

  In general, in a reading device used as a scanner provided in an image forming apparatus, a sub-scan that is perpendicular to the main scanning direction is performed on a carriage that supports a light source and a reflection unit with respect to a reading target such as an original placed on a platen glass. A device that reads an image to be read by inputting reflected light to a light receiving portion while moving in a direction is known.

  In the apparatus disclosed in Patent Document 1 below, when an operation failure is detected when the carriage that supports the light source and the reflection unit is moving, the operation of the carriage is temporarily stopped and then re-driven to restart the carriage. Retry control is performed to continue the operation.

JP 2006-1170 A

  In the apparatus disclosed in Patent Document 1 below, even if retry control is performed while the apparatus is performing an operation other than the reading operation, the apparatus does not perform the image reading operation. Although there is no problem, if the carriage retry control is performed during the reading operation by the device, the carriage operation is temporarily stopped and then the reading operation by the device is resumed from the carriage stop position. If the image read before the carriage stops and the image read after the carriage operation is resumed, the image read by the apparatus may become an abnormal image.

  The present invention has been made in order to solve the above-described problem. When a malfunction occurs when the carriage is moving during a document reading operation, the carriage operation is performed by retry control as in the prior art. It can be prevented that the reading of the document is resumed from the stopped position where it stopped and the read image becomes an abnormal image.

An image forming apparatus according to an aspect of the present invention supports a light source that irradiates light on a document placed on a document table and a reflection unit that reflects reflected light of the light toward a light receiving unit, and performs main scanning. A reading unit that includes a carriage that is reciprocally movable in a sub-scanning direction orthogonal to the direction, and that reads the document in the main scanning direction;
A moving mechanism for reciprocating the carriage in the sub-scanning direction;
A sensor that detects the carriage at a reading start position on one side in the sub-scanning direction in which the reading unit starts the reading;
When the reading unit performs the reading of the document, the moving mechanism moves the carriage from the reading start position to the reading end position on the other side in the sub-scanning direction, and then from the reading end position. A controller that performs a reciprocating movement for moving the return path to the reading start position;
A distance information storage unit for storing in advance a forward movement distance in which the carriage moves in the forward path and a backward movement distance in which the carriage moves in the backward path;
A first movement distance measurement unit that measures a first movement distance of the movement distance of the carriage when the control unit causes the carriage to reciprocate;
When the control unit changes the direction of the carriage and moves it toward the reading start position, the carriage moves from the direction change position where the carriage changes direction until the carriage is detected by the sensor. A second moving distance measuring unit that measures a second moving distance that is a distance;
When the carriage that has moved in the direction of the reading start position is detected by the sensor, the first movement distance measured by the first movement distance measurement unit is the sum of the forward movement distance and the backward movement distance. If the second movement distance measured by the second movement distance measurement unit is smaller than the movement distance and smaller than the return path movement distance, the operation is poor when the carriage is moving on the forward path. If the first movement distance is equal to or greater than the total movement distance, or the second movement distance is equal to or greater than the return movement distance, the carriage moves along the forward path. A determination unit that determines that no malfunction occurred when
The controller is
When the reading unit performs the reading operation of the document, when the determination unit determines that an operation failure has occurred while the carriage is moving in the forward path , the reading unit performs the reading operation. After discarding the original image, the moving mechanism moves the carriage to the reading start position, and then causes the moving mechanism to perform the reciprocating operation so that the reading unit reads the original again. Let
When the reading unit performs the reading operation of the document, when the determination unit determines that no malfunction has occurred when the carriage is moving in the forward path, The read unit does not read the original again without discarding the read image of the original .

  According to the present invention, when a carriage is moving during a document reading operation and a defect occurs in the moving operation, the read image does not become an abnormal image even if reading is resumed thereafter. Can be.

1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a mechanical configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a mechanical configuration of an image reading apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the machine structure inside the reading part in one Embodiment of this invention. 2 is a functional block diagram illustrating a main internal configuration of the image forming apparatus. FIG. It is a flowchart explaining the operation | movement of a malfunction determination when the carriage which supports LED and a mirror is moving. FIG. 6 is a diagram illustrating a state in which a defect occurs in a carriage movement operation during a document reading operation.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of an image forming apparatus 1 according to an embodiment of the present invention.

  An image forming apparatus 1 according to an embodiment of the present invention is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes an apparatus main body 11 including an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, an image reading device 2, and the like. The image reading apparatus 2 includes an ADF (Automatic document feeder), a reading unit 30 and the like.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and a document reading operation execution instruction from the operator regarding various operations and processes that can be executed by the image forming apparatus 1. The operation unit 47 includes a display unit 473 that displays operation guidance to the operator.

  When the image forming apparatus 1 performs a document reading operation, the reading unit 30 optically reads a document fed by the ADF 20 or a document placed on the second platen glass 32, and generates image data. . The image data generated by the reading unit 30 is stored in a built-in HDD or a computer connected to a network.

  When the image forming apparatus 1 performs an image forming operation, image forming is performed based on image data generated by an original reading operation, image data received from a computer connected to a network, or image data stored in a built-in HDD. The unit 12 forms a toner image on the recording paper P as a recording medium fed from the paper feeding unit 14. When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 each receive image data. A toner image is formed on the photosensitive drum 121 by charging, exposing, and developing processes based on the image composed of each color component, and the toner image is transferred onto the intermediate transfer belt 125 by the primary transfer roller 126.

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to become a color toner image. The secondary transfer roller 210 conveys the color toner image formed on the surface of the intermediate transfer belt 125 from the sheet feeding unit 14 through the conveyance path 190 at the nip N with the driving roller 125A with the intermediate transfer belt 125 interposed therebetween. The recording sheet P is transferred. Thereafter, the fixing unit 13 fixes the toner image on the recording paper P to the recording paper P by thermocompression bonding. The recording paper P on which the color image has been formed after completion of the fixing process is discharged to a discharge tray 151.

  The paper feed unit 14 includes a plurality of paper feed cassettes. The control unit 100 (FIG. 5) rotates the pickup roller 145 of the paper feed cassette containing the recording paper of the size specified by the operator's instruction, and the recording paper P contained in each paper feed cassette. Is conveyed toward the nip portion N.

  In the case of performing double-sided printing in the image forming apparatus 1, the recording paper P on which an image is formed on one side from the image forming unit 12 is nipped by the discharge roller pair 159, and then the recording paper P Is switched back by the discharge roller pair 159 and sent to the reverse conveyance path 195, and the conveyance roller pair 19 conveys the recording paper P again upstream in the conveyance direction of the recording paper P with respect to the nip N and the fixing unit 13. Thereby, an image is formed on the other side of the recording paper by the image forming unit 12.

  FIG. 2 is a diagram illustrating a mechanical configuration of the image reading apparatus according to the embodiment of the present invention.

  As shown in FIG. 2, the image reading apparatus 2 includes an ADF 20 and a reading unit 30. The image reading apparatus 2 reads the document MS conveyed by the ADF 20 or the document MS placed on the reading unit 30 based on a control signal input from the control unit 100 (see FIG. 5). Document image data obtained by the reading is stored in the HDD 92 (see FIG. 5).

  The ADF 20 is provided on the upper surface of the reading unit 30 so as to be opened and closed by a hinge or the like. The ADF 20 feeds a plurality of documents MS placed on the document feed tray 22 one by one and conveys them to a document image reading position. The ADF 20 functions as a document pressing cover when reading the document MS placed on the reading unit 30. As shown in FIG. 2, the ADF 20 includes a platen cover 21, a document feed tray 22, a transport roller 25, a registration roller 26, a discharge roller 27, and a document discharge tray 28.

  As shown in FIG. 2, a reading opening OP is formed between the registration roller 26 and the paper discharge roller 27. The reading opening OP is a belt-like opening, and is provided at a bottom portion of the ADF 20, that is, at a portion facing the flow reading position of the reading unit 30 with a predetermined width in the sub-scanning direction (document transport direction). The surface of the document MS conveyed by the ADF 20 is exposed toward the reading unit 30 in the reading opening OP.

  The document discharge tray 28 is a storage unit that stores the document MS supplied from the paper discharge roller 27.

  FIG. 3 is a diagram showing a mechanical configuration of the image reading apparatus according to the embodiment of the present invention.

As shown in FIGS. 2 and 3, the reading unit 30 includes a first platen glass 31, a second platen glass 32, a white reference plate 33, a carriage 34, an optical system unit 35, a condensing lens 36, a CCD (Charge A coupled device) sensor 37 and a carriage detector 38 are provided. The second platen glass 32 is an example of a document table in the claims. The CCD sensor is an example of a light receiving unit in the claims. The reading unit 30 reads the document MS conveyed by the ADF 20 or the document MS placed on the second platen glass 32 by the user in the main scanning direction.

  The white reference plate 33 is a white plate provided between the first platen glass 31 and the second platen glass 32. The white reference plate 33 is read at the time of shading correction, and the read image data is used for the shading correction as white reference data.

The carriage 34 includes an LED (Light Emitting Diode) 34A that irradiates light on a document placed on the second platen glass 32, and a mirror 34C that reflects light reflected by the document MS toward a mirror 35A described later. , Support. The LED 34A is an example of a light source in the claims. The mirror 34C is an example of a reflecting portion in the claims. The carriage 34 is provided so as to be capable of reciprocating along the rail in the sub-scanning direction orthogonal to the main scanning direction. As shown in FIG. 3, the carriage 34 is provided with a light shielding plate at one end (back side) in the main scanning direction. The light shielding plate 34B is provided to detect the position of the carriage 34 by a carriage detection unit 38 (PI (Photo Interrupter) sensor) described later. The light shielding plate 34 </ b> B is provided so as to pass between the light emitting unit 38 </ b> A and the light receiving unit 38 </ b> B provided in the carriage detection unit 38 so as to face each other in the vertical direction as the carriage 34 moves.

  The optical system unit 35 includes a mirror 35A and a mirror 35B. The mirror 35 </ b> A receives the light reflected by the mirror 34 </ b> C of the carriage 34 and further changes the direction downward in the vertical direction. The mirror 35 </ b> B further changes the direction of the light reflected by the mirror 35 </ b> A substantially horizontally and guides the light toward the CCD sensor 37. These mirrors 35A and 35B are fixed to a support member (not shown).

  FIG. 4 is a schematic diagram illustrating a mechanical configuration inside the reading unit according to the embodiment of the present invention.

  The carriage 34 moves to various positions. The carriage 34 moves from the reading start position SP shown in FIG. 4 to the reading end position EP when the document MS placed on the second platen glass 32 is read. The reading start position SP is a position on one side in the sub-scanning direction where the reading unit 30 starts the reading operation. For example, the reading start position SP is placed at a document placement designated position on the second platen glass 32 for reading. This is the position of the edge of the placed document in the sub-scanning direction. Note that the reading end position EP is a position on the other side in the sub-scanning direction where the reading unit 30 ends the reading operation. For example, the reading end position EP is the sub-position of the largest document that can be placed on the second platen glass 32. This is a position away from the reading start position SP to the outside of the document by a fixed distance from the position of the end in the scanning direction.

  The carriage 34 moves to the right in the sub-scanning direction below the second platen glass 32 when the document MS is read. As a result, the light sequentially obtained from the document MS is reflected by the mirror 34 </ b> C supported by the carriage 34 and enters the condenser lens 36.

  The condenser lens 36 condenses the light incident from the mirror and forms an image on the light receiving surface of the CCD sensor 37. The CCD sensor 37 photoelectrically converts the received light into an electrical signal.

  The carriage detection unit 38 detects the carriage 34 at the reading start position SP on one side in the sub-scanning direction where the reading unit 30 starts the reading operation. The carriage detection unit 38 is an example of a sensor in the claims. In FIG. 4, the carriage detection unit 38 is disposed slightly on the side of the reading end position EP from the reading start position SP, and detects that the carriage 34 has returned to the vicinity of the reading start position SP. The carriage detector 38 only needs to detect the carriage 34 at the reading start position SP. For example, the carriage detection unit 38 may be arranged at the same position as the reading start position SP. It may be arranged on the side.

  The carriage detection unit 38 is a PI sensor that is provided on the back side of the light shielding plate 34B provided on the carriage 34 so that the light emitting unit 38A and the light receiving unit 38B are opposed to each other above and below the light shielding plate 34B. The carriage detection unit 38 detects the light shielding plate 34B that passes between the light emitting unit 38A and the light receiving unit 38B as the carriage 34 moves, and outputs a detection signal indicating the detection result to the control unit 10. For example, when the light shielding plate 34B is positioned between the light emitting unit 38A and the light receiving unit 38B, the carriage detection unit 38 outputs an on-state signal as a detection signal, while the light shielding plate 34B is used as the light emitting unit. If it is located out of the space between 38A and the light receiving part 38B, an off-state signal is output. The carriage detection unit 38 outputs an on-state signal to the control unit 10 when the carriage 34 is located near the reading start position SP.

  FIG. 5 is a functional block diagram showing the main internal configuration of the image forming apparatus 1.

  The image forming apparatus 1 includes a control unit 10, an image reading device 2, an image forming unit 12, an image memory 320, an HDD 92, a fixing unit 13, a moving mechanism 93, an operation unit 47, a facsimile communication unit 71, a network interface unit 91, and the like. Prepare. In addition, the same number is attached | subjected to the same component as demonstrated using FIG. 1, and description is abbreviate | omitted.

  The image memory 320 is an area for temporarily storing document image data obtained by reading by the reading unit 30 and temporarily storing data to be printed by the image forming unit 12.

  The HDD 92 is a large-capacity storage device that stores document images and the like read by the reading unit 30.

  The moving mechanism 93 includes a motor 70 and a motor drive circuit 700. The motor 70 applies a driving force to the carriage 34. The motor driving circuit 700 drives the motor 70 by giving a driving pulse to the motor 70 under a command from the control unit 100. Under the command of the control unit 100, the motor drive circuit 700 rotates the motor 70 forward to move the carriage 34 forward, or reversely rotates the motor 70 to return the carriage 34.

  The facsimile communication unit 71 includes an unillustrated encoding / decoding unit, modulation / demodulation unit, and NCU (Network Control Unit), and performs facsimile transmission using a public telephone network.

  The network interface unit 91 includes a communication module such as a LAN board, and transmits / receives various data to / from an external device 200 such as a personal computer on the local area or the Internet via a LAN connected to the network interface unit 91. I do.

The control unit 10 includes a CPU (Central Processing Unit), a RAM, a ROM, a dedicated hardware circuit, and the like. The control unit 10 includes a control unit 100, a distance information storage unit 111, a first movement distance measurement unit 112, a second movement distance measurement unit 113, and a determination unit 114.

  The control unit 100 governs overall dynamic control of the image forming apparatus 1. When the control unit 100 causes the reading unit 30 to read the document on the second platen glass 32, the control unit 100 drives the motor driving circuit 700 to rotate the motor 70 in the forward direction so that the carriage 34 is moved from the reading start position SP. After moving to the reading end position EP, the motor driving circuit 700 is driven to rotate the motor 70 in the reverse direction, and the reciprocating movement is performed again to move to the reading start position SP.

  The distance information storage unit 111 includes a forward movement distance in which the carriage 34 moves in the forward path from the reading start position SP to the reading end position EP, and a backward movement in which the carriage 34 moves in a backward path from the reading end position EP to the reading start position SP. The distance is stored in advance. Specifically, the distance information storage unit 111 stores the number of drive pulses applied to the motor 70 for moving along the forward path as the forward path travel distance. Further, the distance information storage unit 111 stores the number of drive pulses applied to the motor 70 that is required for the carriage 34 to move the return path travel distance as the return path travel distance.

  The first movement distance measurement unit 112 measures a first movement distance of the movement distance of the carriage 34 when the control unit 100 causes the carriage 34 to reciprocate. Specifically, the first movement distance measuring unit 112 measures the number of drive pulses applied to the motor 70 as the first movement distance.

  When the control unit 100 drives the motor drive circuit 700 and reversely rotates the motor 70 to change the direction of the carriage 34 and move the carriage 34 in the direction of the reading start position SP, the second movement distance measuring unit 113 is moved. A second movement distance, which is a movement distance that the carriage 34 moves from when the carriage 34 is detected by the carriage detector 38 from the direction change position where the direction has changed, is measured. Specifically, the second movement distance measurement unit 113 measures the number of drive pulses applied to the motor 70 as the second movement distance.

  When the carriage 34 that has moved in the direction of the reading start position SP is detected by the carriage detection unit 38, the determination unit 114 determines that the first movement distance measured by the first movement distance measurement unit 112 is the forward movement distance and the backward movement distance. When the total moving distance is smaller than the total moving distance and the second moving distance measured by the second moving distance measuring unit 113 is smaller than the return path moving distance, the carriage 34 that supports the LED 34A and the mirror 34C travels the forward path. It is determined that a malfunction has occurred while moving.

  When the control unit 100 causes the reading unit 30 to read the original on the second platen glass 32, the determination unit 114 determines that an operation failure has occurred when the carriage 34 is moving in the forward path. When the determination is made, the motor drive circuit 700 is driven to move the carriage 34 to the reading start position SP, and then the motor drive circuit 700 is caused to reciprocate the carriage 34.

  The control unit 100 is connected to the image reading device 2, the image forming unit 12, the image memory 320, the HDD 92, the fixing unit 13, the moving mechanism 93, the operation unit 47, the facsimile communication unit 71, the network interface unit 91, and the like. Control.

  The control unit 10 functions as the control unit 100 by an operation according to the image processing program. However, the control unit 100 can also be configured by a hardware circuit, regardless of the operation of the control unit 10 according to the image processing program. The same applies to each embodiment unless otherwise specified.

  Next, referring to FIGS. 6 and 7, the flow of operation failure determination when the carriage 34 supporting the LED 34A and the mirror 34C is moving will be described. FIG. 6 is a flowchart for explaining the operation failure determination operation when the carriage 34 supporting the LED 34A and the mirror 34C is moving. FIG. 7 is a diagram for explaining a state in which a defect has occurred in the carriage movement operation during the document reading operation.

  First, when the user sets a document on the second platen glass 32, closes the platen cover 21, and operates the operation unit 47 to give an instruction to start document reading, the control unit 100 causes the motor drive circuit 700. Is driven to place the carriage 34 at the reading start position SP, and the carriage detector 38 detects the carriage 34 at the reading start position SP and outputs an on-state signal. Upon receiving the ON state signal, the control unit 100 outputs a drive pulse applied to the motor 70 to the motor drive circuit 700. When the motor drive circuit 700 rotates the motor 70 in the forward direction under the command of the control unit 100, the carriage 34 starts to move toward the reading end position EP as shown in FIG. Is started (S1 in FIG. 6). In addition, the first movement distance measurement unit 112 that has received the ON state signal from the carriage detection unit 38 starts measuring the first movement distance of the carriage 34 (the number of drive pulses applied to the motor 70).

  Thereafter, the control unit 100 drives the motor drive circuit 700 to reversely rotate the motor 70, thereby changing the direction of the carriage 34 toward the reading start position SP (S2). The second movement distance measuring unit 113 that has received this direction change operation starts measuring the second movement distance of the carriage 34 (the number of drive pulses applied to the motor 70).

  When the carriage detection unit 38 detects the carriage 34 at the reading start position SP, an on-state signal is output. Upon receiving this signal, the determination unit 114 determines whether the first movement distance measured by the first movement distance measurement unit 112 is smaller than the total movement distance of the forward movement distance and the backward movement distance (S3). When the determination unit 114 determines that the first movement distance is equal to or greater than the total movement distance (NO in S3), the determination unit 114 operates when the carriage 34 supporting the LED 34A and the mirror 34C is moving in the forward path and the return path. Judge that no defect occurred. And the control part 100 receives the instruction | indication which complete | finishes a process, and complete | finishes the determination operation | movement of this embodiment.

  When the first movement distance is smaller than the total movement distance of the forward movement distance and the backward movement distance (YES in S3), the determination unit 114 performs an operation failure when the carriage 34 moves on the forward path, or the carriage 34 It is determined that one of the malfunctions occurred while moving on the return path.

  Further, the determination unit 114 determines whether the second movement distance measured by the second movement distance measurement unit 113 is smaller than the return path movement distance (S4). Here, when the carriage 34 malfunctions before the reading end position EP as shown in FIG. 7B, the direction is changed as shown in FIG. 7C, and the carriage 34 reaches the reading end position EP. Therefore, when the second movement distance is smaller than the backward movement distance (YES in S4), the determination unit 114 determines that an operation failure has occurred when the carriage 34 is moving on the forward path (S5). Upon receiving this determination, the controller 100 drives the motor drive circuit 700 to move the carriage 34 to the reading start position SP as shown in FIG. 7D (S6), and then returns the process to S1. Then, the motor drive circuit 700 is caused to perform the reciprocating operation of the carriage 34, and the reading unit 30 is caused to resume the document reading operation. Note that when the carriage 34 moves on the forward path, an operation failure occurs, so that the reading of the document by the reading unit 30 is interrupted, and the image being read stored in the HDD 92 is discarded by the control unit 100. Further, when the reading unit 30 has read the page of the document to the end, if the determination unit 114 determines that a malfunction has occurred when the carriage 34 is moving in the forward path, the control unit 100 discards the image of the document.

On the other hand, when the second movement distance is equal to or longer than the return movement distance in S4 (NO in S4), the carriage 34 has reached the reading end position EP and then changed direction at the reading end position EP. Determines that no malfunction occurred when the carriage 34 is moving on the forward path (S7). And the control part 100 receives the instruction | indication which complete | finishes a process, and complete | finishes the determination operation | movement of this embodiment.

  In this embodiment, when the determination unit 114 determines that a malfunction has occurred when the carriage 34 is moving on the forward path where the reading unit 30 reads a document, the control unit 100 moves the carriage 34. After the stop, it is moved to the reading start position SP, the motor drive circuit 700 is caused to execute the reciprocating operation of the carriage 34, and the reading unit 30 is caused to resume the document reading operation.

  Therefore, in this embodiment, when an operation failure occurs when the carriage 34 is moving during the reading operation of the reading unit 30, the carriage 34 is moved to the reading start position SP after the operation of the carriage is temporarily stopped. Since the reading operation by the reading unit 30 is resumed, the reading of the document is resumed from the stop position even after the carriage operation is temporarily stopped as in the prior art, and the read image is an abnormal image. Can be prevented.

  Conventionally, when an operation failure occurs when the carriage 34 is moving, the user resets the document on the second platen glass 32 when the reading operation by the reading unit 30 is resumed. However, in this embodiment, when the operation failure occurs when the carriage 34 is moving, the reading unit 30 has to be input again by operating the operation unit 47. When the reading operation is resumed, the carriage 34 is moved to the reading start position SP, so that the user resets the document on the second platen glass 32 or operates the operation unit 47 to execute the reading job. There is no need to re-enter instructions.

  Note that the configurations and processes shown in the above embodiments using FIGS. 1 to 7 are only one embodiment of the present invention, and the configurations and processes of the present invention are not limited thereto.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image reading apparatus 10 Control unit 20 ADF
30 Reading unit 31 First platen glass 32 Second platen glass 34 Carriage 34A LED
34B Shielding plate 34C Mirror 38 Carriage detection unit 70 Motor 93 Movement mechanism 100 Control unit 111 Distance information storage unit 112 First movement distance measurement unit 113 Second movement distance measurement unit 114 Judgment unit 700 Motor drive circuit

Claims (2)

Supports a light source that irradiates light on a document placed on a document table and a reflection unit that reflects reflected light of the light toward a light receiving unit, and can reciprocate in a sub-scanning direction orthogonal to the main scanning direction. A reading unit that includes a carriage provided and reads the document in the main scanning direction;
A moving mechanism for reciprocating the carriage in the sub-scanning direction;
A sensor that detects the carriage at a reading start position on one side in the sub-scanning direction in which the reading unit starts the reading;
When the reading unit performs the reading of the document, the moving mechanism moves the carriage from the reading start position to the reading end position on the other side in the sub-scanning direction, and then from the reading end position. A controller that performs a reciprocating movement for moving the return path to the reading start position;
A distance information storage unit for storing in advance a forward movement distance in which the carriage moves in the forward path and a backward movement distance in which the carriage moves in the backward path;
A first movement distance measurement unit that measures a first movement distance of the movement distance of the carriage when the control unit causes the carriage to reciprocate;
When the control unit changes the direction of the carriage and moves it toward the reading start position, the carriage moves from the direction change position where the carriage changes direction until the carriage is detected by the sensor. A second moving distance measuring unit that measures a second moving distance that is a distance;
When the carriage that has moved in the direction of the reading start position is detected by the sensor, the first movement distance measured by the first movement distance measurement unit is the sum of the forward movement distance and the backward movement distance. If the second movement distance measured by the second movement distance measurement unit is smaller than the movement distance and smaller than the return path movement distance, the operation is poor when the carriage is moving on the forward path. If the first movement distance is equal to or greater than the total movement distance, or the second movement distance is equal to or greater than the return movement distance, the carriage moves along the forward path. A determination unit that determines that no malfunction occurred when
The controller is
When the reading unit performs the reading operation of the document, when the determination unit determines that an operation failure has occurred while the carriage is moving in the forward path , the reading unit performs the reading operation. After discarding the original image, the moving mechanism moves the carriage to the reading start position, and then causes the moving mechanism to perform the reciprocating operation so that the reading unit reads the original again. Let
When the reading unit performs the reading operation of the document, when the determination unit determines that no malfunction has occurred when the carriage is moving in the forward path, An image forming apparatus that does not read the original again by the reading unit without discarding the read image of the original . The moving mechanism is
A motor for applying a driving force to the carriage;
A motor drive circuit for driving the motor by applying a drive pulse to the motor,
The distance information storage unit
Storing the pulse number of the drive pulse applied to the motor as the carriage moves on the forward path as the forward travel distance;
Storing the number of drive pulses applied to the motor as the carriage moves on the return path as the return path travel distance;
The first moving distance measuring unit is
When the control unit causes the carriage to reciprocate,
Measuring the number of pulses of the drive pulse applied to the motor as the first movement distance;
The second movement distance measuring unit is
When the control unit changes the direction of the carriage and moves it toward the reading start position,
The image forming apparatus according to claim 1, wherein the number of drive pulses applied to the motor is measured as the second movement distance.