JP2006211544A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of avoiding image degradation even when an intermittent drive control is performed. <P>SOLUTION: In the image forming apparatus 1, an original document platen 3 includes a slant line L extending in a sub scanning direction in a peripheral area F3 while displacing in a main scanning direction regularly. A memory 7 stores a main scanning direction position of the slant line L corresponding to an interruption position when reading is interrupted by the intermittent drive control. A controller 9 makes a scanner 11 read the slant line L during forwarding after setting back once, and simultaneously restarts the reading of image information when the slant line L is detected at the main scanning direction position which agrees to an address of the slant line L corresponding to the interruption position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus.

  In general, an image forming apparatus such as a copying machine or a multifunction machine having a copying function is provided with an original platen on which an original is placed and driven below in the original platen in the sub-scanning direction. A scanner unit capable of reading image information is provided.

  As a conventional image forming apparatus of this type, the read image information is digitized and temporarily stored in a memory, and when the memory is full, the remaining amount of memory remains, and the drive of the scanner unit is stopped. A device that performs intermittent drive control for interrupting reading of a document is already known.

  Specifically, the intermittent drive control is performed after the scanner unit is stopped due to the memory full, and then the scanner unit is temporarily moved backward in the sub-scanning direction from the interruption position, and the scanner is vacated when the memory is vacant. A series of operations such as accelerating the scanner and reading from the time when the scanner reaches the interruption position are performed.

  In the intermittent drive control, the drive of the scanner unit is usually controlled by open loop control by a stepping motor.

As related techniques, for example, techniques shown in Patent Documents 1 and 2 below have already been proposed.
JP-A-10-51599 JP 2003-333287 A

  However, in the conventional image forming apparatus, the scanner unit is driven by open loop control, and the position where reading is interrupted is not grasped by a control unit such as a CPU. For this reason, the accuracy when the scanner unit is retracted is insufficient, and as a result, a phenomenon in which a seam occurs in the read image information is likely to occur.

  An object of the present invention is to provide an image forming apparatus capable of avoiding image deterioration even when intermittent drive control is performed.

  An image forming apparatus according to a first aspect includes a document table, an image reading unit, a storage unit, and a control unit. The document table has a document reading area including a document placement area, and an identification that extends in the sub-scanning direction while being regularly displaced in the main scanning direction in a peripheral area other than the document placement area of the document reading area. Has a display. The image reading unit includes a scanner unit that can read the image information of the document placed in the document placement region in the sub-scanning direction and can detect the identification display. The storage unit can store image information within a range of a predetermined storage capacity, and can store an identification display main scanning direction position corresponding to an arbitrary sub-scanning direction position. The control unit performs intermittent drive control for the scanner unit to interrupt reading of image information when the free space in the storage unit becomes a predetermined amount or less.

  When the reading is interrupted by the intermittent drive control, the storage unit stores the main scanning direction position of the identification display corresponding to the interruption position that is the sub-scanning direction position where the reading is interrupted. In addition, when the reading is interrupted by the intermittent drive control, the control unit temporarily retracts the scanner unit backward from the interruption position, and then the free space of the storage unit becomes larger than a predetermined amount. When the identification display is read at the position in the main scanning direction that coincides with the position in the main scanning direction of the identification display corresponding to the interruption position, the identification display is read while moving forward. Resume reading.

  In this apparatus, by utilizing the fact that the document reading area is larger than the document placement area, an identification display is attached to the peripheral area, and this can be detected by the scanner unit.

  Since the identification display used here extends in the sub-scanning direction while being displaced in the main scanning direction, a different position in the main scanning direction corresponds to each position in the sub-scanning direction. Therefore, by storing the main scanning direction position of the identification display at the interruption position, when the identification display is detected at the same main scanning direction position later, the corresponding sub-scanning direction position can be accurately specified. Thus, reading by the scanner unit can be accurately resumed from the interruption position. Thereby, even when intermittent drive control is performed, it is possible to suppress the occurrence of image seams and avoid image degradation.

  In addition, here, by using the identification display, the above-described effect can be obtained without providing any special parts.

  In the present invention, examples of the regularly-displaced identification display include a straight line inclined with respect to the sub-scanning direction. However, the present invention is not limited to this, and a function curve, other figures, etc. are predicted by calculation. Possible ones.

  Further, the front refers to the sub-scanning direction in which the scanner unit is driven during reading, and the rear refers to the opposite direction.

  An image forming apparatus according to a second aspect is the apparatus according to the first aspect, wherein the identification display is a slanted line inclined with respect to the sub-scanning direction.

  In this apparatus, an accurate interruption position is specified by using hatched lines that allow easy calculation of the position in the sub-scanning direction by calculation.

  The image forming apparatus according to a third aspect is the apparatus according to the first aspect, wherein the identification display is a plurality of oblique lines that are inclined with respect to the sub-scanning direction and arranged in the sub-scanning direction.

  In this apparatus, by using a plurality of oblique lines, it is possible to increase the inclination angle of each oblique line with respect to the sub-scanning direction, and thereby it is possible to specify the interruption position with a smaller number of pixels in the sub-scanning direction.

  An image forming apparatus according to a fourth aspect of the present invention is the apparatus according to any one of the first to third aspects, wherein the document table serves as a reference for placing a document on one end in the main scanning direction of the document placement region. In addition to having a placement reference position, an identification display is provided in the main scanning direction area adjacent to the document placement reference position in the peripheral area.

  In this device, since the identification display is attached at a location close to the reference position, the influence of deviation in the main scanning direction during image adjustment is suppressed, contributing to more accurate identification of the interruption position. Will be.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the control unit further reads the identification display while the scanner unit is moved backward in accordance with the intermittent drive control. When the identification display at the main scanning direction position that matches the main scanning direction position of the identification display at the interruption position is read, it is necessary for the scanner unit to perform acceleration for restarting reading from the interruption position. The scanner unit is further retracted from the interruption position by the distance.

  In this apparatus, the identification display is read while the scanner unit is moved backward in accordance with the intermittent drive control, and the identification display is detected at the main scanning direction position that coincides with the main scanning direction position of the identification display at the interruption position. In such a case, the scanner unit is further retracted from the interruption position by a distance necessary to perform acceleration necessary to obtain a speed required for the scanner unit to resume reading from the interruption position.

  According to the present invention, by utilizing the fact that the document reading area is wider than the document placement area, it is possible to attach an identification display to the peripheral area and cause the scanner unit to detect this.

  Since the identification display used here extends in the sub-scanning direction while being displaced in the main scanning direction, a different position in the main scanning direction corresponds to each position in the sub-scanning direction. Therefore, by storing the main scanning direction position of the identification display at the interruption position, when the identification display is detected at the same main scanning direction position later, the corresponding sub-scanning direction position can be accurately specified. Thus, reading by the scanner unit can be accurately resumed from the interruption position. Thereby, even when intermittent drive control is performed, it is possible to suppress the occurrence of image seams and avoid image degradation.

  In addition, here, by using the identification display, the above-described effect can be obtained without providing any special parts.

<Configuration of image forming apparatus>
1 and 2 show an image forming apparatus 1 in which an embodiment of the present invention is adopted.

  The image forming apparatus 1 is a multifunction machine having functions as a copying machine, a printer, a facsimile machine, and a scanner, and includes a document table 3 (see FIG. 3), an image reading unit 5, and a memory 7 (storage unit). ), A control unit 9, and another input / output unit.

  The document table 3 is made of contact glass provided on the upper portion of the image forming apparatus 1 and has a document reading area F3 including a document placement area F1 and a peripheral area F2.

  The document placement area F1 has a document placement reference position P that serves as a reference when placing a document on one end side in the main scanning direction (the back side in FIG. 1) and on the rear end side in the sub-scanning direction. In the main scanning direction area adjacent to the document placement reference position P in the peripheral area F2, a black oblique line L inclined by a predetermined angle with respect to the sub-scanning direction is drawn. The oblique line L extends in the sub-scanning direction while being displaced in the main scanning direction at a constant rate.

  The image reading unit 5 includes a scanner unit 11 and a drive unit 13 for driving the scanner unit 11.

  The scanner unit 11 includes a linear array CCD as an image pickup device, an optical system, and the like. The scanner unit 11 receives a main scanning synchronization signal output from the control unit 9 and is driven in the sub-scanning direction to place a document. The image information of the document placed in the area F1 can be read in the main scanning and sub-scanning directions. Further, the scanner unit 11 can detect the position in the main scanning direction by reading the oblique line L.

  The main scanning synchronization signal is indicated by a signal Sn1 in FIG. 4 and indicates the reading width of the document by two peaks. The other signals Sn2 and Sn3 are both output signals from the image sensor, and are shown on the same time axis as the signal Sn1 (left and right direction in FIG. 4), and are strong in accordance with the color density of the read image information. The peak of the height is output. The signal Sn2 indicates a signal output when the image sensor of the scanner unit 11 is positioned forward in the sub-scanning direction, and the signal Sn3 indicates a signal output when the image sensor is positioned rearward in the sub-scanning direction.

The drive unit 13 has a stepping motor (not shown).
The memory 7 includes a RAM 15 and a ROM 17. The ROM 17 stores a control program for an input / output unit such as the image reading unit 5 and data of an expression representing a straight line approximating the oblique line L, and an image sensor output signal. Software including an algorithm for calculating the position in the main scanning direction from the peak of the oblique line L is stored.

  In the RAM 15, image information read by the image reading unit 5 is AD-converted and stored within a predetermined storage capacity, and the free space becomes smaller than the data amount for one page of the document (memory full). When this occurs, the position in the main scanning direction of the oblique line L at the position where the reading operation is interrupted is stored as an address.

  The control unit 9 is for controlling the input / output unit such as the image reading unit 5 and performing image processing, and is constituted by a microcomputer including a CPU.

  When the memory is full in the RAM 15, the control unit 9 performs intermittent drive control. Specifically, the control unit 9 decelerates and stops the scanner unit 11, and further retracts backward from the interruption position to free up the RAM 15. When the capacity is equal to or more than one page of the document (memory empty), the scanner unit 11 is accelerated and reading is resumed from the middle position again.

  At this time, the control unit 9 causes the scanner unit 11 to read the oblique line L even during the backward movement, and when the oblique line L is detected at the main scanning direction position that coincides with the address of the oblique line L at the interruption position, The scanner unit 11 is further retracted from the interruption position by a distance required for the acceleration necessary to obtain the speed necessary for the scanner unit 11 to resume the reading operation.

  In addition, when the scanner unit 11 moves forward again, the oblique line L is read, and when the oblique line L is detected at a position in the main scanning direction that coincides with the address of the oblique line L at the interruption position, an image information reading operation is performed. To resume.

  The image forming apparatus 1 further includes an image forming unit 25, an operation panel 21, an automatic document feeder (hereinafter referred to as ADF) 23, and the like as other input / output units.

  The image forming unit 25 is for forming an image on a sheet based on the image information read by the image reading unit 5, and includes a photosensitive drum, a developing device, a fixing device, and the like (not shown). The operation panel 21 has a plurality of operation keys 21a and a liquid crystal display 21b. The operation keys 21a include a start button (not shown) for instructing reading or copying. The ADF 23 is for feeding a plurality of documents continuously onto the document table 3, and is provided so as to be openable and closable with respect to the document table 3.

<Operation of Image Forming Apparatus>
Next, the operation of the image forming apparatus 1 will be described with reference to FIGS.

  FIG. 5 is an explanatory diagram showing a change in speed of the scanner unit 11 accompanying the intermittent drive control and the sub-scanning synchronization signal Sn4, the memory full detection signal Sn5, and the memory empty detection signal Sn6 output from the control unit 9 on the same time axis. is there.

FIG. 6 is a flowchart for explaining the reading operation of the image forming apparatus 1.
When the image forming apparatus 1 reads a document, the document is placed on the document placement area F1 of the document table 3 and the start key is pressed (S1). Then, the scanner unit 11 is driven in the sub-scanning direction to read the image information of the document for each line in the main scanning direction (S2), and the read image information is sequentially stored in the memory 7.

  Here, when the memory full occurs before the reading of all the areas of the document is finished (S3 → S4), the reading operation is interrupted (S5), and the address of the oblique line L at the interruption position is stored. (S6) The scanner unit 11 is decelerated, stops at the front position of the interruption position, and then moves backward (S7). At this time, the oblique line L is also read, and when the oblique line L is detected at a position in the main scanning direction that coincides with the address of the oblique line L at the interruption position (S8), the scanner unit 11 resumes reading from the interruption position. The vehicle moves backward by a distance required to perform acceleration necessary to obtain a necessary speed (S9).

  When the memory becomes empty (S10), the scanner unit 11 is accelerated (S11), and reading is resumed from the time when the oblique line L is detected at the main scanning direction position that coincides with the address of the oblique line L at the interruption position (S12). (S13). When the reading of all the areas of the document is completed (S3), the reading operation ends.

  According to the image forming apparatus 1 described above, by causing the scanner unit 11 to read the position of the oblique line L in the main scanning direction, the position in the sub-scanning direction where the reading of the document is interrupted can be specified accurately, so intermittent drive control is performed. Even in such a case, it is possible to suppress the occurrence of seams in the image and to avoid image deterioration.

  Further, here, the interruption position can be accurately specified using a simple oblique line L without providing any special parts.

<Other embodiments>
(A) The identification display may be composed of a plurality of oblique lines. In this case, for example, when the angle θ shown in FIG. 3 is set to 45 ° or more, it becomes possible to detect the displacement of one pixel in the sub-scanning direction per line, and therefore, it is possible to specify the interruption position with higher accuracy. It becomes possible.

  (B) Further, the identification display is not limited to diagonal lines, and if the position in the sub-scanning direction can be easily determined from the position in the main scanning direction by calculation, the identification display can be performed in a predetermined function curve or in the sub-scanning direction. Other displays including graphics such as elongated triangles can be employed.

  (C) The intermittent drive control described in the above embodiment may be implemented in a hardware manner using an ASIC or the like instead of a mode performed by the CPU executing a corresponding program.

1 is an external view showing an image forming apparatus in which an embodiment of the present invention is adopted. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus. FIG. 2 is a plan view showing a document table of the image forming apparatus. FIG. 3 is a diagram illustrating a signal supplied to a scanner unit of the image forming apparatus and an output signal from an image sensor. Explanatory drawing for demonstrating the speed change etc. of the said scanner part. 6 is a flowchart for explaining the operation of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Original stand 5 Image reading part 7 Memory (memory | storage part)
9 Control unit 11 Scanner unit 15 RAM
F1 Document placement area F2 Document reading area F3 Peripheral area L Diagonal lines (identification display)
P Document placement reference position

Claims (5)

An identification display having a document reading area including a document placement area and extending in the sub-scanning direction while regularly displacing in the main scanning direction in a peripheral area other than the document placement area of the document reading area. An original platen,
An image reading unit having a scanner unit capable of reading image information of a document placed in the document placement region by being driven in a sub-scanning direction and detecting the identification display;
A storage unit capable of storing the image information within a range of a predetermined storage capacity and storing a main scanning direction position of the identification display corresponding to an arbitrary sub-scanning direction position;
A control unit for performing intermittent drive control for interrupting reading of the image information when the free space of the storage unit becomes a predetermined amount or less with respect to the scanner unit;
The storage unit stores a main scanning direction position of the identification display corresponding to an interruption position that is a sub-scanning direction position at which the reading is interrupted when the reading is interrupted by the intermittent drive control,
When the reading is interrupted by the intermittent drive control, the control unit temporarily retracts the scanner unit backward from the interruption position, and then the free space of the storage unit becomes larger than a predetermined amount. In this case, the identification display is read while moving forward, and the identification display is detected at a position in the main scanning direction corresponding to the position in the main scanning direction of the identification display corresponding to the interruption position. The reading of the image information is resumed,
Image forming apparatus.   The image forming apparatus according to claim 1, wherein the identification display is a diagonal line inclined with respect to the sub-scanning direction.   The image forming apparatus according to claim 1, wherein the identification display is a plurality of oblique lines that are inclined with respect to the sub-scanning direction and arranged in the sub-scanning direction.   The document table has a document placement reference position that serves as a reference for placing the document at one end in the main scanning direction of the document placement region, and is adjacent to the document placement reference position in the peripheral region. The image forming apparatus according to claim 1, wherein the identification display is provided in a scanning direction area.   The control unit reads the identification display while the scanner unit is moved backward in accordance with the intermittent drive control, and at a main scanning direction position that coincides with the main scanning direction position of the identification display at the interruption position. When the identification display is detected, the scanner unit is further moved from the interruption position by a distance necessary to perform acceleration necessary to obtain a speed for the scanner unit to resume reading from the interruption position. The image forming apparatus according to claim 1, wherein the image forming apparatus is moved backward.

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