JP5784527B2 - Document reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a document reading apparatus and an image forming apparatus that guide a light frame of a document while moving a moving frame that guides light from a light source to an image surface of the document and guides reflected light from the image surface to an image sensor.

  A document reading device that reads a document image is provided as a single peripheral device of a personal computer, or mounted as an image scanning unit in an image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine. In general, an original reading operation in an original reading apparatus irradiates light from a light source such as a cold cathode tube lamp onto an image surface of an original placed on a platen glass, and reflects light from the image surface to an image sensor such as a CCD sensor. Incident light is reflected and the reflected light is converted into an electrical signal by the image sensor. Further, in this document reading operation, the light source light is guided to the image surface of the document, and the irradiation position is changed while moving the moving frame body that guides the reflected light from the image surface to the image sensor along the image surface of the document, The entire image surface of the original is scanned.

  Since the moving amount of the moving frame is managed based on the home position, the moving frame needs to be at the home position in the standby state in order to start the scanning operation promptly from the scan start instruction. If the moving frame is not at the home position in the standby state, a positioning operation for moving the moving frame to the home position must be performed before the start of scanning. For this reason, the scanning operation cannot be started quickly, and the time required for the scanning operation is increased accordingly, and convenience is lowered. Therefore, the moving frame is held at the home position by continuously supplying a hold current to the motor that drives the moving frame.

JP 2002-44996 A

  However, when the hold current is continuously supplied to the motor as in the prior art, the power consumption in the standby state becomes a problem. For example, in the case of a stepping motor driven at 24 [V] 600 [mA], power of 14.4 [W] is consumed as power consumption by the hold current. In addition, as in Patent Document 1, it has been proposed to reduce power consumption by reducing the hold current value of the motor other than during operation to a level that does not affect the hold operation in the printer. Power consumption in the standby state is required, and the fundamental problem cannot be solved.

  An object of the present invention is to provide an original reading apparatus and an image forming apparatus that can start a scanning operation promptly from a scan start instruction even when a moving frame is displaced from a home position.

The document reading apparatus according to the present invention includes a moving frame that guides light from a light source to an image surface of a document and guides reflected light from the image surface of the document to an image sensor in a sub-scanning direction along the image surface of the document. A document reading apparatus that executes a scanning operation while moving the image to acquire image data of a reading range, and a home position detecting unit that detects a home position of the moving frame, and when a start of scanning is instructed, An original reading unit that moves the moving frame forward and then moves the moving frame back to the home position to acquire image data in a range wider than the reading range in the sub-scanning direction; and the moving frame Measured by the return path travel distance measuring means for measuring the travel distance of the return path movement, and the preset travel distance of the forward path movement and the return path travel distance measuring means of the moving frame. When said less than the difference preset value of the moving distance of the backward movement, comprising a reading range extracting means for extracting the image data of the reading range of the image data obtained by the original reading means It is a feature.
Furthermore, the document reading apparatus of the present invention, when the difference between the moving distance of the moving the moving distance and the return of the forward movement is equal to or greater than the preset value, may be executed rescanning .
Furthermore, in the document reading apparatus of the present invention, when the rescan operation is executed , the document reading unit may acquire only image data in the reading range.
According to another aspect of the present invention, there is provided an image forming apparatus including the above-described original reading apparatus and a recording unit that forms an image based on image data in the reading range acquired by the original reading apparatus .

  According to the present invention, even when the moving frame body is deviated from the home position, the scanning operation can be started promptly from the scan start instruction without positioning the moving frame body at the home position. Since it is not necessary to pass a hold current to the motor that moves the body, there is an effect that power consumption during standby can be reduced.

1 is a schematic cross-sectional view showing an internal configuration of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of the image forming apparatus illustrated in FIG. 1. It is explanatory drawing for demonstrating the positioning operation | movement using the home position sensor shown in FIG. 5 is a flowchart for explaining a scanning operation in the embodiment of the image forming apparatus according to the present invention. FIG. 6 is an explanatory diagram for explaining a scanning operation in the embodiment of the image forming apparatus according to the invention.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
An image forming apparatus 1 according to the present embodiment is a copying machine using an electrophotographic system. Referring to FIG. 1, a document reading unit 10, a document feeding unit 3, a body unit 4, an operation unit 6, and the like. It has. The document feeding unit 3 is disposed at the upper part of the document reading unit 10, and the document reading unit 10 is disposed at the upper part of the main body unit 4, and between the document reading unit 10 and the main body unit 4. A paper discharge space 8 is formed.

  The operation unit 6 is provided with a liquid crystal display unit 61 and operation buttons 62. The user operates the operation unit 6 and inputs an instruction to perform various settings of the image forming apparatus 1 and execute various functions such as a scan operation and image formation. The liquid crystal display unit 61 displays the state of the image forming apparatus 1, displays the image forming status and the number of copies, and can be used as a touch panel to perform various settings such as functions such as double-sided printing and black-and-white reversal, magnification setting, and density setting. It has become. The operation buttons 62 include a start button for instructing start of a scan operation and image formation, a stop button for instructing stop of the scan operation and image formation, and a reset button used when various settings of the image forming apparatus 1 are set to a default state. A numeric keypad for inputting the number of printed sheets and the like is provided.

  The document reading unit 10 guides light from a light source such as a cold-cathode tube lamp to the image surface of the document MS and guides reflected light from the image surface to an image sensor such as a CCD sensor, a platen glass 12, and the like. And a document reading slit 13. The moving frame 11 is fixed to a toothed belt 16 that is bridged between the motor 14 and the pulley 15, and the moving frame 11 is placed on the platen glass 12 by driving the motor 14. It is configured to move along the image surface of the document MS and scan (scan) the image surface of the document MS. In the present embodiment, it is assumed that the moving frame 11 is provided with a light source and an image sensor. The platen glass 12 is an original table made of a transparent member such as glass. The document reading slit 13 is a slit formed in a direction orthogonal to the document transport direction by the document feeding unit 3.

  When reading the document MS placed on the platen glass 12, the document MS placed on the platen glass 12 is moved in the main scanning direction while moving the movable frame 11 along the platen glass 12 in the sub-scanning direction. Image data is acquired by scanning line by line, and the acquired image data is output to the main unit 4. When reading the document MS conveyed by the document feeding unit 3, the moving frame 11 is moved to a position facing the document reading slit 13, and the document by the document feeding unit 3 is moved through the document reading slit 13. The document MS is read in synchronism with the conveying operation to acquire image data, and the acquired image data is output to the main unit 4.

  The document feeding unit 3 includes a document placement unit 31, a document discharge unit 32, and a document transport mechanism 33. The documents MS placed on the document placement unit 31 are sequentially fed out one by one by the document conveyance mechanism 33 and conveyed to a position facing the document reading slit 13, and then discharged to the document discharge unit 32. The document feeding unit 3 is configured to be retractable, and the upper surface of the platen glass 12 can be opened by lifting the document feeding unit 3 upward.

  The main body unit 4 includes a recording unit 5 that records on the recording paper P by an electrophotographic process, and includes a paper feed cassette 41, a paper feed roller 42, a paper transport path 43, transport rollers 44 and 45, and a discharge roller. 46. The paper feed roller 42, the transport rollers 44 and 45, and the discharge roller 46 function as a transport unit that transports the recording paper P. The recording paper P stored in the paper feed cassette 41 is fed one by one to the paper transport path 43 by the paper feed roller 42 and transported to the recording unit 5 by the transport roller 44. Then, the recording paper P on which recording has been performed by the recording unit 5 is discharged to the paper discharge space 8 by the discharge roller 46.

  The recording unit 5 includes a photosensitive drum 51, a charger 52, an optical scanning unit 53, a developing unit 54, a transfer roller 55, a fixing unit 56, and a cleaning unit 57. In the image formation by the recording unit 5, first, the surface of the photosensitive drum 51 is uniformly charged by the charger 52, and based on the image data read by the document reading unit 10, the optical scanning unit 53 performs the image reading of the photosensitive drum 51. An electrostatic latent image is formed by scanning the surface. Next, the electrostatic latent image formed on the surface of the photosensitive drum 51 is developed by the developing unit 54 to form a toner image. The toner image formed on the surface of the photosensitive drum 51 is transferred to the recording paper P while the recording paper P fed from the paper feed cassette 41 passes through the nip portion between the photosensitive drum 51 and the transfer roller 55. The The toner image transferred to the recording paper P is thermally fixed to the recording paper P while passing through the fixing unit 56.

  FIG. 2 is a block diagram illustrating a schematic configuration of the image forming apparatus 1. The document reading unit 10, the document feeding unit 3, the transport unit (the paper feed roller 42, the transport rollers 44 and 45, the discharge roller 46), the recording unit 5, and the operation unit 6 are connected to the control unit 7. The operation is controlled by 7. The control unit 7 is connected to an image processing unit 71, a storage unit 72, and a reading range extraction unit 73.

  The control unit 7 is an information processing unit such as a microcomputer including a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for controlling the operation of the image forming apparatus 1. The control unit 7 reads out a control program stored in the ROM and develops the control program in the RAM, thereby controlling the entire apparatus according to predetermined instruction information input from the operation unit 6.

  The image processing unit 71 is a unit that performs predetermined image processing on image data. For example, image improvement processing such as enlargement / reduction processing, gradation adjustment, and density adjustment is performed.

  The storage unit 72 is a storage unit such as a semiconductor memory or an HDD (Hard Disk Drive). The storage unit 72 stores image data acquired by reading a document by the document reading unit 10 and stores various management information. Yes.

  The reading range extraction unit 73 performs an image data extraction operation for extracting only image data in the reading range from the image data temporarily stored in the storage unit 72. The reading range is an area where image data is acquired by a scanning operation, and the entire area or a partial area of the platen glass 12 becomes a reading range depending on the setting from the operation unit 6.

  Referring to FIG. 2, the document reading unit 10 includes a motor driver 17 that drives the motor 14, a reading control unit 18 that controls the motor driver 17, and a home position sensor 19 (hereinafter referred to as an HP sensor 19). ing. In the present embodiment, a stepping motor that rotates in units of basic step angles is used as the motor 14 that moves the moving frame 11, and the rotation angle of the motor 14, that is, the moving distance of the moving frame 11 is determined by the reading control unit 18. Is determined by the number of pulses (number of steps) of the pulse signal output from. The pulse signal output from the reading control unit 18 is converted into a motor driving current by the motor driver 17 and the motor 14 is driven.

  The HP sensor 19 is attached to the moving frame body 11, and the reading control unit 18 executes a positioning operation for moving the moving frame body 11 to the home position based on the output from the HP sensor 19. As the HP sensor 19, for example, a transmissive sensor is used as shown in FIG. The casing 20 of the document reading unit 10 is provided with a shielding plate 21 at a position detected by the HP sensor 19. In the positioning operation by the reading control unit 18, first, as shown by an arrow A in FIG. After detecting 21, the moving frame 11 is moved by a predetermined step and then stopped. Therefore, as shown in FIG. 3B, the state where the shielding plate 21 is detected by the HP sensor 19 is the home position of the movable frame 11.

Next, a scanning operation for reading a document placed on the platen glass 12 by the document reading unit 10 will be described in detail with reference to FIGS.
The controller 7 enters a standby state waiting for a scan start instruction from the operation unit 6 after the power is turned on or after the scan operation is completed (step A1). In the present embodiment, the hold current is not applied to the motor 14 in the standby state of Step A1. Accordingly, when an external factor such as vibration or impact is applied to the document reading unit 10, the moving frame 11 may move.

  When a scan start instruction is input from the operation unit 6, the control unit 7 instructs the document reading unit 10 to perform a scan operation. When the scanning operation is instructed, the reading control unit 18 of the document reading unit 10 drives the motor 14 that outputs a pulse signal to the motor driver 17, and the moving frame body is indicated by an arrow X in FIG. The forward movement is performed to move 11 in the sub-scanning direction along the platen glass 12 (step A2). The moving distance of the moving frame 11 in the forward movement in step A2, that is, the step number X (hereinafter referred to as the forward step number X) by which the motor 14 rotates in the forward movement is set in advance, and the movement in step A2 The moving distance of the frame 11 is always constant. FIG. 5 shows an example in which the entire surface of the platen glass 12 is set as the reading range.

  During the forward movement in step A2, the document MS placed on the platen glass 12 is scanned to acquire image data, and the acquired image data is temporarily stored in the storage unit 72 via the control unit 7 ( Step A3). Scanning during the forward movement is started at a preset timing after the movement of the moving frame 11 is started, and the scanning range in the sub-scanning direction in which the moving frame 11 moves is wider than the reading range (platen glass 12). Is set. The scanning range is set on the assumption that the moving frame 11 is located at the home position (HP) at the start of scanning, and the number L of steps in the scanning range in the sub-scanning direction in which the moving frame 11 moves is It is set wider by B steps on the upstream side and the downstream side than the step number A of the scanning range in the sub-scanning direction of the reading range (platen glass 12).

  Next, the reading control unit 18 of the document reading unit 10 drives the motor 14 that outputs a pulse signal to the motor driver 17, and moves the moving frame 11 to the home position (indicated by an arrow Y in FIG. 5A). HP is started (step A4), and the number of steps Y (hereinafter referred to as the number of backward steps Y) by which the motor 14 is rotated by the backward movement is measured (step A5).

  Next, the reading control unit 18 of the document reading unit 10 monitors the detection of the shielding plate 21 by the HP sensor 19 (step A6). When the shielding plate 21 is detected by the HP sensor 19, the moving frame 11 is set to a predetermined state. After the step movement, stop (step A7). Thereby, the moving frame 11 is stopped at the home position (HP). In addition, the reading control unit 18 of the document reading unit 10 outputs the measured number Y of return path steps to the control unit 7.

  Next, the control unit 7 compares the forward step number X and the backward step number Y (step A8), and the difference Z between the forward step number X and the backward step number Y is smaller than the preset step number B. (Step A9). When the difference Z between the number of forward path steps X and the number of backward path steps Y is smaller than the preset number B of steps in step A9, the control unit 7 temporarily stores the reading range extraction unit 73 in the storage unit 72. An image data extraction operation for extracting only the image data in the reading range from the stored image data is instructed.

  The reading range extraction unit 73 instructed to perform the image data extraction operation first determines whether or not the forward path step number X and the backward path step number Y are equal, that is, the forward path travel distance and the backward path travel distance of the moving frame 11. It is determined whether or not they are equal (step A10). When the number of forward path steps X is equal to the number of backward path steps Y in step A10, the reading range extraction unit 73 is downstream of the upstream B steps in the sub-scanning direction of the image data temporarily stored in the storage unit 72, and downstream. The side B step is cut (step A11), and the scanning operation is terminated. When the number of forward steps X is equal to the number of backward steps Y in step A10, that is, when the moving distance of the moving frame 11 is equal to the moving distance of the backward route, as shown in FIG. The moving frame 11 is positioned at the home position (HP) at the start. Therefore, only the image data in the reading range is extracted by cutting the upstream B step and the downstream B step in the sub-scanning direction of the image data temporarily stored in step A11.

  Next, if the forward step number X and the backward step number Y are not equal in step A10, the reading range extracting unit 73 determines whether the backward step number Y is larger than the forward step number X. In other words, it is determined whether or not the moving distance of the return frame is greater than the moving distance of the moving frame 11 (step A12). In step A12, when the return path step number Y is larger than the forward path step number X, that is, when the return path movement distance is larger than the forward path movement distance of the movable frame 11, the reading range extraction unit 73 temporarily stores in the storage unit 72. The upstream (B−Z) step and the downstream (B + Z) step in the sub-scanning direction of the stored image data are cut (step A13), and the scanning operation is terminated. When the number of inbound steps X is larger than the number of outbound steps X in step A12, as shown in FIG. 5B, the moving frame 11 is closer to the platen glass 12 than the home position (HP) at the start of scanning. The position is shifted by the difference Z. Therefore, only the image data in the reading range is extracted by cutting the upstream (B-Z) step and the downstream (B + Z) step in the sub-scanning direction of the image data temporarily stored in step A11. Will be.

  In step A12, when the number of return path steps Y is not larger than the number of forward path steps X, that is, when the number of backward path steps Y is smaller than the number X of forward path steps, the reading range extraction unit 73 is temporarily stored in the storage unit 72. The upstream (B + Z) step and the downstream (B−Z) step in the sub-scanning direction of the image data being cut are cut (step A14), and the scanning operation is terminated. In step A12, when the number of return path steps Y is not larger than the number of forward path steps X, as shown in FIG. 5C, the moving frame 11 moves away from the platen glass 12 more than the home position (HP) at the start of scanning. Therefore, the position is shifted by the difference Z. Therefore, only the image data in the reading range is extracted by cutting the upstream (B + Z) step and the downstream (B−Z) step in the sub-scanning direction of the image data temporarily stored in step A11. Will be.

  As described above, in this embodiment, even when the scanning operation is performed in a state where the moving frame 11 is deviated from the home position (HP), the image data in the reading range can be reliably acquired. Therefore, it is not necessary to position the moving frame 11 at the home position (HP), and it is not necessary to apply a hold current to the motor 14 in the standby state.

When the difference Z between the number of forward steps X and the number of backward steps Y is greater than or equal to a preset number of steps B in step A9, the control unit 7 displays “the moving frame 11 is at the home position” on the liquid crystal display unit 61. A message notifying that “the rescan is performed greatly deviating from (HP)” is displayed to alert the user (step A15), and the process returns to step A2 to execute the rescan operation. When performing the rescanning operation, it is preferable that only the image data in the reading range is acquired because the moving frame 11 is located at the home position (HP) at the start of scanning.

  In this embodiment, a stepping motor is used as the motor 14, and the difference Z in the movement distance between the forward path and the return path is measured by the number of steps. However, a servo motor is used as the motor 14. Also good. In this case, the difference in the moving distance between the forward path and the return path can be measured using a rotary encoder that measures the rotation amount, rotation angle, and rotational position, or a linear encoder that measures movement in the row direction.

  Furthermore, in the present embodiment, the image data is acquired when the moving frame 11 moves in the forward path, but the image data may be acquired when the moving frame 11 moves in the backward path.

  As described above, according to the present embodiment, the light from the light source is guided to the image surface of the document MS placed on the platen glass 12, and the moving frame that guides the reflected light from the image surface of the document MS to the image sensor. In the document reading apparatus that performs the scanning operation while moving the body 11 along the image surface of the document MS in the sub-scanning direction and acquires image data in the reading range, the document reading unit 10 is instructed to start scanning. After moving the moving frame 11 forward, the moving frame 11 is moved backward until the home position (HP) is detected by the HP sensor 19, and image data in a range wider than the reading range in the sub-scanning direction is obtained. At the same time, the reading control unit 18 measures the number of steps Y of the return frame movement of the moving frame 11, and the reading range extraction unit 73 sets the preset forward path moving step of the moving frame 11. Based on the difference Z between the step number Y of movement backward that was measured to flop number X, it is configured to extract the image data of the reading range. With this configuration, even when the moving frame 11 is deviated from the home position (HP), the scanning operation can be started promptly from the scan start instruction without positioning the moving frame 11 at the home position (HP). In addition, since it is not necessary to pass a hold current to the motor 14 that moves the moving frame 11 in the standby state, power consumption during standby can be reduced.

Further, according to the present embodiment, when the difference Z between the number of steps X of the forward movement and the number of steps Y of the backward movement is equal to or larger than a preset value B, the rescan operation is executed. ing. With this configuration, even when the moving frame 11 is greatly deviated from the home position (HP), it is possible to reliably acquire image data in the reading range. Further, when executing the rescan operation, the time of the rescan operation can be shortened by acquiring only the image data in the reading range.

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Document feeding part 4 Main body part 5 Recording part 6 Operation part 7 Control part 8 Paper discharge space 10 Document reading part 11 Moving frame 12 Platen glass 13 Document reading slit 14 Motor 15 Pulley 16 Toothed belt 17 Motor Driver 18 Reading controller (return path travel distance measuring means)
19 Home position (HP) sensor (Home position detection means)
DESCRIPTION OF SYMBOLS 20 Housing | casing 21 Shielding plate 31 Original placement part 32 Original discharge part 33 Original conveyance mechanism 41 Paper feed cassette 42 Paper feed roller 43 Paper conveyance path 44, 45 Conveyance roller 46 Discharge roller 51 Photosensitive drum 52 Charger 53 Optical scanning part 54 Developing Unit 55 Transfer Roller 56 Fixing Unit 57 Cleaning Unit 61 Liquid Crystal Display Unit 62 Operation Button 71 Image Processing Unit 72 Storage Unit 73 Reading Range Extraction Unit

Claims (4)

The light source light is guided to the image surface of the document, and the moving frame that guides the reflected light from the image surface of the document to the image sensor is moved in the sub-scanning direction along the image surface of the document and the scan operation is executed. A document reading device for acquiring image data of a reading range,
Home position detecting means for detecting a home position of the moving frame;
When the start of scanning is instructed, the moving frame is moved forward and then the moving frame is moved back to the home position to acquire image data in a range wider than the reading range in the sub-scanning direction. Document reading means;
Return path moving distance measuring means for measuring the moving distance of the return path movement of the moving frame;
When the difference between the movement distance of the forward movement set in advance of the moving frame and the movement distance of the backward movement measured by the return movement distance measuring unit is smaller than a preset value, the document reading An original reading apparatus comprising: reading range extraction means for extracting image data of the reading range from the image data acquired by the means. Wherein when the difference between the moving distance of the forward movement and the moving distance of the backward movement of more than the predetermined value, the document reading apparatus according to claim 1 wherein there to perform a rescan operation. 3. The document reading apparatus according to claim 2 , wherein when executing the rescanning operation, the document reading unit acquires only image data in the reading range. An original reading apparatus according to any one of claims 1 to 3 ,
An image forming apparatus comprising: a recording unit configured to form an image based on image data of the reading range acquired by the document reading apparatus.

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