JPH10210229A - Image reader and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a document image and a form from shifting in position and part of the image from being absent by changing image data of an unfixed type document into image data in the same format even if the document carried by an automatic document feeder is an unfixed type document and a document conveyance position is a center reference or corner reference. SOLUTION: On the basis of the size of a document detected by a document size detecting circuit and copy magnification set on a control panel 200, a printer CPU 130 selects a cassette which contains forms with optimum size. Then a read-in start position of image data for inputting the image data from a CCD line sensor to a page memory is read out of a ROM 102 and stored in an RAM 104 according to inputted copy magnification. At this point, when the size of forms calculated by the printer CPU 130 does not match with the size of an image area, a document area which is based upon the size of forms can be copied is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image corresponding to image data by an electrophotographic process and outputting the image to a sheet.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic process, in a state where a photosensitive member is charged to a predetermined surface potential by a charging device, light whose intensity is modulated in accordance with image data from an exposure device. Is irradiated, the latent image formed on the photoconductor corresponding to the image data is developed with the toner supplied by the developing device, converted into a toner image, and transferred to the photoconductor by the transfer device. When a transfer bias voltage having the same polarity as the provided surface potential is applied from the back side of the transfer material, that is, the recording sheet, the transfer bias voltage is transferred to the sheet electrostatically attracted to the photoconductor, and the heat from the fixing device causes the transfer. It is melted and adhered to the paper by the pressure provided at the same time.

In this type of image forming apparatus, in recent years,
A number of multifunction copiers have been proposed in which a printer function and a facsimile function (a printer unit is used for reception and a reading unit is used for transmission) are added in addition to a normal copying function. Further, there have been proposed many examples in which an automatic document feeder is mounted which automates the supply of a document to the image reading unit and the removal of the document from the image reading unit.

[0004]

However, when a document of a special size (atypical) is conveyed by using an automatic document feeder and the document image is copied, the output image is shifted from the center of the image or a part of the image is missing. There is such a problem. This is because the automatic document feeder cannot accurately detect the size of an irregular document (there is no detection mechanism).

[0005] The difference between the length of the original document in the main scanning direction and the actual length of the non-standard document in the main scanning direction, which is recognized when the original image is copied by conveying the non-standard document using the automatic document feeder, is determined. Appears as image shift. The purpose of this invention is
An object of the present invention is to provide an image forming apparatus capable of copying an original of an irregular size by using an automatic original feeder and appropriately copying the original on a sheet.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above problems, and has a platen on which a document is placed;
Reading means for changing the starting point of the effective reading area in accordance with the size of the original and scanning the image of the target area with respect to the original placed on the original table; Based on input means for setting and inputting a document as an arbitrary size, and a size of the document input by the input means,
An image reading apparatus comprising: a control unit that changes the start point of the read effective area and performs scanning by the reading unit.

Further, according to the present invention, a document table on which a document is placed, and a starting point of a reading effective area are changed with respect to the document placed on the document table in accordance with the size of the document. A scanning unit that scans the image to generate continuous image data, a storage unit that stores the image data generated by the scanning unit, and a document placed on the platen having an arbitrary size. Input means for setting and inputting, and based on the size of the document input by the input means, to change the starting point of the effective reading area for the reading means,
And a control unit for changing the read start position of the image data stored in the storage unit and outputting the image data, thereby providing an image reading apparatus.

Further, according to the present invention, an original platen on which an original is placed, and a starting point of an effective reading area are changed with respect to the original placed on the original platen according to the size of the original. A reading unit that performs scanning for reading the image to generate continuous image data, a storage unit that stores the image data generated by the reading unit, and a document placed on the platen.
Input means for setting and inputting the size as an arbitrary size; and storing the information in the storage means so as to change the end point of the effective reading area for the reading means based on the size of the document input by the input means. Control means for changing the read end position of the read image data and outputting the image data,
The present invention provides an image reading apparatus comprising:

Still further, according to the present invention, an image reading operation is performed by scanning a document placed on a document and a document placed on the document in a main scanning direction and a sub-scanning direction. Reading means for changing the effective reading area in the main scanning direction and the sub-scanning direction in accordance with the size of the original to perform scanning for reading an image in the target area; and reading the original placed on the original platen. Input means for setting and inputting the size along the main scanning direction and the sub-scanning direction as an arbitrary size; and, based on the size of the document input by the input means, the reading validity for the reading means. Control means for changing the area to perform scanning.

Still further, according to the present invention, there is provided a document table on which a document is placed, an automatic document feeding means for automatically feeding a document from a predetermined position to the document table, and an automatic document feeding means. When the original is fed to the platen using the scanner, the start and end points of the effective reading area are changed according to the size of the original, and the image of the target area is scanned for scanning. Reading means for scanning an image in a target area by changing the start point of the effective reading area without changing the start point regardless of the size of the document, An input unit for setting and inputting a document placed on a table as an arbitrary size; and using the automatic document feeder for the reading unit based on the size of the document input by the input unit. Are the starting point of the reading effective area and When the end point is changed and the automatic document feeder is used, control means for changing the end point without changing the start point of the effective reading area and performing scanning is provided. An image reading apparatus is provided.

Still further, according to the present invention, a document table on which a document is placed, and a starting point of an effective reading area for the document placed on the document table are changed according to the size of the document. Reading means for performing scanning for reading the image of the area, input means for setting and inputting the original placed on the original platen as an arbitrary size, and, based on the size of the original input by the input means, Control means for causing the reading means to change the start point of the effective reading area to perform scanning, image forming means for forming an image on an image carrier according to an image read by the reading means based on the control of the control means, The present invention provides an image forming apparatus comprising:

Still further, according to the present invention, a document table on which a document is placed and a starting point of a reading effective area are changed with respect to the document placed on the document table in accordance with the size of the document. A scanning unit that scans the image of the area to generate continuous image data, a storage unit that stores the image data generated by the scanning unit, and a document placed on the platen having an arbitrary size. Input means for setting and inputting the image data, and image data stored in the storage means for changing the starting point of the effective reading area for the reading means based on the size of the document input by the input means. A control unit that changes the read start position of the image data to output image data, an image forming unit that forms an image on an image carrier according to an image read by the reading unit based on the control of the control unit,
The present invention provides an image forming apparatus comprising:

Still further, according to the present invention, an original platen on which an original is placed, and a starting point of an effective reading area for the original placed on the original platen are changed according to the size of the original. A scanning unit that scans the image of the area to generate continuous image data, a storage unit that stores the image data generated by the scanning unit, and a document placed on the platen having an arbitrary size. Input means for setting and inputting the image data, and image data stored in the storage means for changing the end point of the effective reading area to the reading means based on the size of the document input by the input means. Control means for changing the read end position of the image data to output image data, image forming means for forming an image on an image carrier according to the image read by the reading means under the control of the control means,
The present invention provides an image forming apparatus comprising:

Still further, according to the present invention, an image reading operation is performed by scanning a document placed on the document table in the main scanning direction and the sub-scanning direction with respect to the document placed on the document table. Reading means for changing the effective reading area in the main scanning direction and the sub-scanning direction in accordance with the size of the original to perform scanning for reading an image in the target area; and reading the original placed on the original platen. Input means for setting and inputting the size along the main scanning direction and the sub-scanning direction as an arbitrary size; and, based on the size of the document input by the input means, the reading validity for the reading means. An image forming apparatus comprising: control means for changing the area for scanning and reading; and image forming means for forming an image on an image carrier in accordance with the image read by the reading means based on the control of the control means. To It is intended to provide.

Still further, according to the present invention, there is provided a document table on which a document is placed, an automatic document feeding means for automatically feeding a document from a predetermined position to the document table, and an automatic document feeding means. When the original is fed to the platen using the scanner, the start and end points of the effective reading area are changed according to the size of the original, and the image of the target area is scanned for scanning. Reading means for scanning an image in a target area by changing the start point of the effective reading area without changing the start point regardless of the size of the document, An input unit for setting and inputting a document placed on a table as an arbitrary size; and using the automatic document feeder for the reading unit based on the size of the document input by the input unit. Are the starting point of the reading effective area and In the case where the end point is changed and the above-mentioned automatic document feeder is used, the control means for changing the end point without changing the start point of the effective reading area and performing scanning by scanning, based on the control of this control means Image forming means for forming an image on an image carrier according to the image read by the reading means,
The present invention provides an image forming apparatus comprising:

[0016]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an image forming apparatus, that is, an electrophotographic digital copying apparatus 2 is located on an apparatus main body 4 and an upper part of the apparatus main body 4, and is formed to be openable and closable with respect to a document table to be described later. An automatic document feeder 6 that functions as a document holder that feeds an object, that is, a document one by one, toward a document table and makes the document adhere to the document table is provided. To the left of the apparatus main body 4, a finisher 8 for processing a recording sheet holding an image formed by the apparatus main body 4 is connected. The automatic document feeder 6 is connected to the main body of the apparatus by a signal line 6a, and the finisher 8 is connected to the main body of the apparatus by a signal line 8a. That the automatic document feeder 6 and the finisher 8 are connected.

The apparatus main body 4 has an upper portion facing the automatic document feeder 6 in a closed state.
And a document guide 11 which is arranged at one end of the document table 10 and indicates a position where the document should be set on the document table 10. In the vicinity of the document table 10 surrounding the document table 10, a control panel described in detail in FIG.

An exposure lamp 12 and an exposure lamp 1 for illuminating a document set on the document table 10 are provided below the document table 10.
Auxiliary reflector 1 for condensing light from document 2 on document D
3 and a first mirror 14 for bending reflected light from the document D to the left in the figure. Exposure lamp 12,
The auxiliary reflection plate 13 and the first mirror 14 are fixed to the first carriage 15, and are arranged to be movable in parallel with the document table 10 as the first carriage 15 moves. The first carriage 15 is provided with a pulse motor (not shown) transmitted by a not-shown toothed belt or the like.
The motor reciprocates in the left-right direction in FIG.

A driving mechanism (not shown) such as a toothed belt (not shown) moves the document table 10 to the left in the drawing, in the direction in which the reflected light reflected by the first mirror 14 is guided.
A second carriage 20 movably formed in parallel with the document table 10 is provided.

The second carriage 20 has a first mirror 14
A second mirror 21 that bends the reflected light from the document guided by the document downward in the figure and a third mirror 22 that bends the light rightward in the figure are arranged at right angles to each other. In addition, the second carriage 20 is moved in parallel with the original table 10 by following the first carriage 15 at half the speed at which the first carriage 15 is moved.

Below the first carriage 15 and within the plane including the optical axis of the light turned back by the third mirror 22 of the second carriage 20, the light reflected by the third mirror 22 An imaging lens 23 for forming an image at a magnification, and a CCD sensor 24 for converting the reflected light provided with the converging property by the imaging lens 23 into an electric signal, that is, image data, are arranged.

A photoconductor drum 30 as an image carrier is rotatably located at a substantially center of the apparatus main body 4 in a predetermined direction. The photosensitive drum 30 is rotated at a predetermined rotation speed by a motor (not shown).

At a predetermined position around the photosensitive drum 30, a charging charger 31 for charging the photosensitive layer on the drum surface to a predetermined surface potential, a laser diode (not shown) as a light source, and a laser beam from the laser diode are linearly irradiated. Polygonal mirror 32a, polygonal mirror 3
2a includes an imaging lens 32b for giving a predetermined imaging characteristic to the laser light deflected by 2a, and a mirror 32c for reflecting the laser light given the predetermined imaging characteristic by the imaging lens 32b toward the photosensitive drum 30. The surface of the photosensitive drum 30 is exposed by exposing the surface of the photosensitive drum 30 with laser light from a laser diode whose intensity is modulated in accordance with image data supplied from an image processing unit described later, that is, image information to be formed. A laser exposure device 32 for forming an electrostatic latent image on the surface of the photosensitive drum 30 by supplying toner as a developer to the electrostatic latent image formed on the photosensitive layer on the surface of the photosensitive drum 30 by exposure by the laser exposure device 32 Developing roller 33
a toner image formed on the photosensitive drum 30 on a recording sheet P fed from a sheet cassette described later, and a sheet P on which the toner image is transferred.
Transfer / separation device 34 for separating the photoconductor drum 30 from the photoconductor drum 30; a pre-cleaning static elimination device 35 for improving the cleaning performance by removing the charge remaining on the photoconductor drum 30 before cleaning; Cleaning device 36 for cleaning toner remaining on the surface
A static eliminator 37 for neutralizing the potential remaining on the surface of the photosensitive drum 30 is arranged in this order.

On the bottom of the apparatus main body 4 located below the photosensitive drum 30, a plurality of paper feeders are stacked vertically and are detachably mounted from the front side of the apparatus main body 4 as a multi-stage paper feeder. 40 are arranged.

The multi-stage paper feeder 40 includes an upper cassette 4 for storing a plurality of types of recording paper P of various sizes.
1, including a middle cassette 42 and a lower cassette 43,
Each of the cassettes 41, 42, and 43 can store, for example, about 500 A4 size copy paper, B4 size copy paper, and A3 size copy paper placed so as to be conveyed along the longitudinal direction. Is formed.

At predetermined positions of the upper cassette 41, the middle cassette 42, and the lower cassette 43, pickup rollers 44a, 44b, and 44c for taking out the sheets stored in the respective cassettes 41, 42, and 43 one by one are arranged. ing.

Each pickup roller 44a, 4
4b and 44c, the respective cassettes 41, 42 and 4
The conveyance rollers 45 for separating the sheets P one by one are located at positions where the leading end of the sheets P taken out of the sheet P 3 pass.
a, 45b and 45c, and separation rollers 46a, 46b and 46 disposed integrally with the respective transport rollers.
c is arranged. The separation rollers 46a, 46b, and 46c are arranged so that their axes are in parallel with the mutually combined transport rollers and are in contact with a predetermined pressure, and rotate in a direction opposite to the rotation direction of the transport rollers. As a result, only the uppermost one of the sheets P taken out of each cassette is sent out to a transport path described later.

On the right side of the multi-stage paper feeder 40 in the figure, there is provided a large-capacity cassette 47 capable of storing about 3000 frequently used sheets, for example, A4 size sheets.

At a predetermined position of the large-capacity cassette 47, a pickup roller 48 for taking out the sheets P stored in the large-capacity cassette 47 one by one is arranged. A separation mechanism 49 including a pair of upper and lower transport rollers 49a and a separation roller 49b is arranged between the pickup roller 48 and the photosensitive drum 30. The separation mechanism 49 rotates the separation roller 49b in a direction opposite to the direction in which the transport roller 49a is rotated, and thereby the pickup roller 48 rotates the separation roller 49b at the top of the sheet taken out of the large capacity cassette 47.
Only the sheets are sent to a transport path described later. A paper feed sensor 47a for detecting the conveyance state of the paper taken out of the large capacity cassette 47 by the pickup roller 48 is disposed between the pickup roller 48 and the separation mechanism 49.

On the upper part of the large-capacity cassette 47, a side cassette 50 capable of feeding paper P independently of the cassettes 41, 42, 43 and the large-capacity cassette 47, and the side cassette 50 integrated with the side cassette 50. And a manual feeder 51 capable of feeding one sheet or an irregular form of paper. It should be noted that paper empty switches 50a and 51a for detecting that the paper has run out are disposed at the distal ends of the side cassette 50 and the manual feeder 51, respectively.

Between the manual feeder 51 and the photosensitive drum 30, a pickup roller 52 for taking in the paper P from the manual feeder 51 and a transport roller 53 for transporting the paper P taken in by the pickup roller 52 are provided. Note that the transport roller 53 is a side cassette 5
It is also used to feed paper from zero.

The respective cassettes 41, 42 and 43
Further, between the large-capacity cassette 47 and the photosensitive drum 30, a transport path 54 for guiding the paper P from each of the cassettes 41, 42 and 43 and the large-capacity cassette 47 toward the photosensitive drum 30 is formed. This transport path 54
Through a transfer area between the photosensitive drum 30 and the transfer peeling device 34, it is formed integrally with a transport belt and a fixing device described later, and extends to the outside of the apparatus main body 4.

Between the cassettes in the transport path 54, the transport rollers 45a and the separation rollers 46a, 45b and 46b and the rollers 45c and 46c disposed corresponding to the respective cassettes are guided toward the photosensitive drum 30 over the rollers 45c and 46c. Conveyance sensors 54a, 54b and 54 for detecting a sheet to be fed
c and the respective rollers 45a and 46a, 4
A plurality of pairs of transport rollers 55 for transporting the sheets sent out by 5b and 46b and 45c and 46 are arranged, and the transport rollers 55 immediately afterward are directed toward the photosensitive drum 30 by the respective transport sensors 54a, 54b and 54c. The transfer timing is matched.

Near the photosensitive drum 30 and on the upstream side of the transport path 54, the inclination of the sheet P guided along the transport path 54 is corrected, and the leading end of the toner image on the photosensitive drum 30 and the sheet P And an aligning roller 56 that feeds the sheet P to the transfer area at the same speed as the moving speed of the outer peripheral surface of the photosensitive drum 30.

An aligning sensor 56a for detecting the arrival of the sheet P at the aligning roller 56 is disposed in front of the aligning roller 56, that is, on the side of the transport roller 55.

In the direction in which the paper passing through the transfer area advances, a transport belt 57 for guiding the paper on which the image (toner image) has been transferred by the transfer and peeling device 34 toward a fixing device described later is incorporated. ing.

In the direction in which the paper P is transported by the transport belt 57 and where heat is not easily applied to the photosensitive drum 30, a heat roller pair whose roller surfaces are pressed against each other is included, and the toner image is transferred. A fixing device 58 is provided for fixing the toner image on the sheet P by pressing the toner image and the sheet P while heating the formed sheet P to melt the toner image.

On the side wall of the copying machine 2 facing the fixing device 58, a sheet P on which the toner image is fixed by the fixing device 58 is provided.
Is connected. The finisher 8 includes a paper discharge tray 59a that holds the paper P on which the toner image has been fixed after passing through the fixing device 58, and is disposed between the fixing device 58 and the discharge tray 59a. The discharged copy sheet P is held under control of a discharge switching unit 60 that guides the sheet to a sheet reversing unit or a discharge tray 59a to be described later. The finisher 8 has a pair of reversing rollers 59b for reversing the surface of the sheet discharged from the discharge switching unit 60 onto the discharge tray 59 by reversing the surface on which the toner image has been transferred, and one copy of the discharged sheet. It has a stapler 59c for stapling each time.

The discharge switching unit 60 is disposed between the first and second discharge rollers 61 and 62 for propelling the sheet P passed through the fixing device 58 and between the first and second discharge rollers 61 and 62. Further, there is provided a sorting gate 63 for sorting the sheet passed through the fixing device 58 to the discharge tray 59a (finisher 8) or to a sheet reversing section described later. The second discharge roller 6
A discharge sensor 6 for detecting the transport state of the sheet sent toward the finisher 8 is provided between the finisher 8 and the finisher 8.
2a is arranged.

The reversing mechanism 64 temporarily accumulates a sheet that has already passed through the transfer area and the fixing device 58 and has a toner image fixed on at least one surface thereof.
A reversing guide path 66 that is arranged between the temporary stacking unit 65 and the sorting gate 63 and guides the paper sorted by the sorting gate 63 and guided to the temporary stacking unit 65;
A pickup roller 67 for taking out the sheets stacked in the temporary stacking section 65 one by one; a reversing conveyance path 68 for guiding the sheet P taken out by the pickup roller 67 from the temporary stacking section 65 to the aligning roller 56 again; The paper feed roller 69 feeds the paper P guided to the transport path 68 toward the aligning roller 56.
A paper jam sensor 65a for detecting a paper jam is disposed in the reversing guide path 66. Before the paper feed roller 69, a paper stop for measuring the timing at which the paper feed roller 69 feeds the paper to the subsequent stage is provided. A switch 68a is provided. The paper stop switch 68a determines that a paper jam (jam) has occurred when the paper is not detected within a predetermined time after the start of the operation of the pickup roller 67 and the paper feed roller 69.

The automatic document feeder 6 has a cover 71, and the rear edge of the cover 71 is attached to the rear side of the upper surface of the copying machine 2 by a hinge device (not shown). As described above, the apparatus 6 is formed so as to be openable and closable with respect to the document table 10 by rotating and displacing the entire apparatus 6.

On the left side of the upper surface of the cover 71, a document feeding table 72 for holding a plurality of documents D is arranged. Documents D set on the document feeder 72 are sequentially taken out one by one from the left side of the document feeder 72 in the drawing, that is, one end of the automatic document feeder 6, and the document table 10 is A pickup roller 73 for supplying to one end side is arranged.

At a predetermined position of the document feeding table 72, a document detection sensor 72a for detecting whether or not the document D is set on the document feeding table 72 is provided. In the document taking-out direction of the pickup roller 73, that is, in the document table 10 side,
A paper feed roller 74 for sending out the original D taken out by the pickup roller 73 toward the original table 10, and an original for temporarily holding the original D fed by the paper feed roller 74 to remove the inclination of the leading end of the original. A lining roller 75 is provided. An aligning sensor 7 for detecting that the document D is being conveyed toward the aligning roller 75 is provided between the aligning roller 75 and the paper feed roller 74.
5a is arranged.

At a position inside the cover 71 where the automatic document feeder 6 is closed and opposed to the document table 10, a size enough to cover almost the entire document table 10 is given. Document D conveyed from document feeder 72 via roller 74 and aligning roller 75
A transport belt 76 for transporting the original to a predetermined position on the document table 10 is arranged. The transport belt 76 is wound around belt rollers 77 arranged in a pair on the left and right sides in the figure, and is rotated by a belt driving mechanism (not shown) in both the right and left directions in the figure.

In the right portion of the automatic document feeder 6, a reversing roller 7 for sending out the document D, which is moved from the left side in the figure to the right side in the figure by the conveyor belt 76, toward the outside of the cover 71.
8. A pinch roller 79 for pressing the document D against the reversing roller 78, and whether the document D conveyed by the reversing roller 78 and the pinch roller 79 is returned to the conveyance belt 76 again or discharged to a predetermined discharge position, that is, the cover 71. The flapper 80 to be switched, a paper discharge roller 81 for discharging the document D conveyed by the reversing roller 78 when the flapper 80 is switched to the discharge side, and a jam for detecting the jam of the document D near the reversing roller 78 A sensor 82 and the like are arranged.

FIGS. 2 to 6 are block diagrams schematically showing the control mechanism of the laser exposure type digital copying apparatus 2 shown in FIG. Electrophotographic digital copying machine 2
As shown in FIG. 2, the basic unit 301 of the digital copying apparatus 2 receives and stores image data from the basic unit 301, and stores the stored image data in the basic unit 3 again.
01 is transferred to the page memory unit 302 which transfers the data to the P.01.

The basic unit 301 includes a main control unit 311 for controlling the apparatus main body 4 and a system bus 310 to which various devices or circuits including the main control unit 311 are connected. Connected
CCD which will be described later in detail with reference to FIG.
A reading unit for transmitting image information to the sensor 24 and the CCD sensor 24; an image forming unit including the photosensitive drum 30 and its peripheral device, which will be described below with reference to FIG. 4 in the apparatus main body 4, a facsimile 312, and an image processing unit 313.
The system bus 310 is connected to the system bus connection unit 31.
4 is connected to a system bus of the page memory unit 302 which will be described later. The image processing unit 313 is connected to the page memory unit 30 by the image data interface 315.
2 image buses.

As shown in FIG. 3, the main control unit 311
Is a system CPU 1 of the digital copying apparatus 2 including an apparatus main body 4, an automatic document feeder 6, and a finisher 8.
And a ROM connected to the system CPU 100 for storing an initial program for warming up the laser exposure type copying apparatus 2 so that an image can be formed.
(Read-only memory) 102, an R that temporarily stores numerical data input from the control panel
AM (random access memory) 104, NVM (non-volatile memory) 106 for holding numerical data set when assembling the device 2 semi-permanently, image memory 108,
It comprises a timer memory 110, a timer 112, an internal interface 122, an external interface 124 and the like.

The internal interface 122 is connected to a control panel 200 shown in the later part of FIG.
The finisher 8 shown in FIG. 1 is connected to the external interface 124. Also, the external interface 124
Is connected to an external device (such as a personal computer).

The system CPU 100 includes a printer CPU 130 for controlling the apparatus main body 4 and a facsimile 312.
Is connected. The printer CPU 130 includes an image forming unit including the photosensitive drum 30 shown in FIG. 4 and its peripheral devices, and the CCD sensor 24 and the sensor 24 shown in FIG.
Is connected to a reading unit for transmitting image information.

As shown in FIG. 4, the image forming section includes a motor driving section 132 for driving a motor for rotating the photosensitive drum 30 of the apparatus main body 4 shown in FIG.
4, the transfer sensors 54a, 54b and 54c, the aligning sensor 56a, the discharge sensor 62a, and the jam sensor 6
5a and a sensor input unit 140 that detects the output of the paper stop switch 68a and notifies the printer CPU 130 and the system CPU 100 of the paper transport state inside the apparatus main body 4, a cleaning blade (not shown) of the cleaning device 36, and a switching mechanism. A mechanism driving unit 141 for turning on / off a solenoid or a driving coil (not shown) used for the fixing unit 60 or the like, a lighting time of a fixing lamp of the fixing device 58 and a passing current value are controlled to set a fixing temperature in a predetermined range. A high-voltage output control unit 143 that controls the output voltage of the lamp control unit 142, the charging unit 31, the transfer unit and the peeling unit of the transfer and peeling device 34, and the pre-cleaning neutralization device 35, and a neutralization device control unit that controls the neutralization device 37. 144, the pickup roller 44a,
In order to rotate each of the rollers 44b and 44c, 48 and 51 at a predetermined timing, a paper feed controller 145 that controls a paper feed motor disposed corresponding to each roller, and the transport rollers 45a, 45b and 45c, 55 # (4) In order to rotate the aligning roller 56 and the like at a predetermined timing, a transport control unit 146 that controls motors arranged corresponding to the rollers, and a laser drive that drives a laser diode (not shown) of the laser exposure device 32 Circuit 15
0, a modulation circuit 15 that modulates the intensity of the laser light emitted from the laser diode by the emission control by the laser drive circuit 150 in accordance with the image data to be formed.
1. A polygon motor control circuit 152 for controlling the number of rotations of a polygon motor formed integrally with the polygon mirror 32a of the laser exposure device 32, and the like.

As shown in FIG. 5, the reading unit includes the exposure lamp 12 and the auxiliary reflector 1 in the apparatus main body 4 shown in FIG.
A motor driver 160 that drives a pulse motor (not shown) that reciprocates the first carriage 15 including the third and first mirrors 14 in parallel with the document table 10 at a predetermined speed. A document controlling a document motor arranged corresponding to each roller in order to rotate the pickup roller 73 and the sheet feeding roller 74 at a predetermined timing to control the terminal voltage of the exposure lamp 12 to reach the terminal voltage of the exposure lamp 12. Paper feed controller 164,
In order to stop and rotate the aligning roller 75 rotated by the document feed control unit 164 at a predetermined timing, a solenoid (not shown) or a drive coil is turned on / off.
Aligning roller controller 166 to be turned off, flapper 8
The document conveyed toward the platen 10 is rotated by rotating one of the belt rollers 77 around which the discharge / reversal control unit 168 that controls the position A document transport control unit 170 for guiding the document to a predetermined position and discharging or reversing the document as necessary, a document size detection circuit for detecting the size (length) of the document based on the output of the aligning sensor 75a 172, the jam sensor 82 or the document detection sensor 72
a of the printer CPU 130 (and the system CP
U100) by the sensor input unit 174, etc.
Be composed.

As shown in FIG. 5, the output of the CCD sensor 24 is supplied to an image quality improvement circuit 184 via an A / D conversion circuit 181, a resolution conversion circuit 182, a shading correction circuit 183, and a line buffer. Circuit 1
A predetermined characteristic is given by the image processing unit 313 including the image processing unit 85 and the like, and is transferred to a predetermined area of the page memory unit 302 via the printer CPU 130 via the image data interface and is stored (stored).

When an image is formed from image data read for each main scanning line and stored in the line buffer memory, the timing of reading from the line buffer memory is changed, and after image processing at the time of output, The stored image data can be output from an arbitrary clock of the horizontal synchronizing signal, and the time difference is suppressed within one line even when the image synchronizing clock frequency of the image processing circuit and the image synchronizing clock frequency of the laser driving circuit are different. The period of the synchronous clock signal of the image signal of the image processing circuit and the laser exposure device 3
The image is exposed on the photosensitive drum 30 by absorbing the difference in the period of the synchronous clock of the image signal of the laser drive circuit supplied to 2 in one main scanning line. The line buffer memory is used for using the line buffer memory as a buffer memory, as will be described later with reference to FIG. 7. The write address and the read address can be changed, and both can be arbitrarily set by the system CPU 100. it can.

FIG. 7 shows the relationship between the document table 10 and the line buffer. When image data is taken into the line buffer memory, the data is set to be stored in order from the rear end of the apparatus 2. Is conveyed at the center of the platen 10 as an example. When the pixel Cn corresponding to the position of the center of the platen is centered, the pixels corresponding to both ends of a document of a certain size are ld. , Td
Becomes If the document transport position is based on the corner, it is considered that image data corresponding to the document edge is stored from the image data at the edge of the document table 10. In addition,
In any case, by setting the image data ld to td corresponding to the document as the effective image data, the outside of the effective image data can be deleted and a common image format can be used.

Next, the page memory unit 302 will be described with reference to FIG. 2 again. The page memory unit 302 has a built-in page memory 321 and a communication memory 322 for temporarily storing (storing) the supplied image data.
1, a system control unit 323 for controlling access to the page memory 321; an address control unit 324 for generating addresses of the page memory 321; and an image bus 3 used for data transfer between devices in the page memory unit 302.
25, the page memory 3 via the control bus 326 and the image bus 325 used for transferring control signals between each device in the page memory unit 302 and the system control unit 324.
When transferring image data via the image interface 315 between the data control unit 327 and the basic unit 301 when transferring data between the device 21 and another device, the basic unit 301 Data interface control unit 32 used to transfer image data between
8. When the image data is transmitted to a device having a different resolution, the image data is converted into the resolution of another device, or the image data received from the device having a different resolution can be formed by the image forming unit of the basic unit 301. A resolution conversion / binary rotation circuit 329 that converts binary image data into 90-degrees or rotates binary image data by 90 degrees, for a device that compresses and transmits or stores image data for transmission by facsimile or storage on an optical disk. A compression / expansion circuit 330 for compressing the image data input to the image data and expanding the image data supplied in a compressed form for visualization printing is connected to the image data interface control unit 315, and the image data is transmitted from the image forming unit. When outputting image data at 90 degrees or -90
Multi-value rotation memory 33 used when outputting by rotating by degrees
1 and the like.

FIG. 6 shows the facsimile 312 inside the main body 4 shown in FIG. 1, that is, the basic unit 301 shown in FIG.
FIG. 3 is a schematic block diagram for explaining. As shown in FIG. 6, a facsimile 312 is connected to a public line via a modem 190, which is a modem for analog line connection, and is a C / C device for encoding / decoding binary image data.
ODECs 191 and 192, an EPROM 193 for a communication control program, a memory for storing image data, and a pseudo SR backed up by a battery 194.
The AM 195, the work RAM 196 used for performing various kinds of processing of image data, the additional memory 197, and the received data received by facsimile,
And an interface 198 for outputting to the image processing unit 313 of FIG.

FIG. 8 is a schematic plan view showing an example of a control panel incorporated in the digital copying apparatus 2 shown in FIGS. As shown in FIG.
The control panel 200 sets a copy key 202 for setting a copy mode for executing a copy function, a FAX key 204 for setting a FAX mode for executing a facsimile function, and a printer mode for executing a printer function. A printer key 206 is provided.

Further, the control panel 200 includes F
In the AX mode, it is used for calling abbreviated registration FAX numbers and abbreviated registration, and corresponds to a number from "0" to "9" for inputting a numerical value such as the number of copies or the size of an irregular document in the copy mode. Numeric keypad 208 for outputting a signal, print key 210 for instructing the start of copying, clear / stop key 2 used to correct the number of copies or to stop the copying operation, etc.
12, an all clear key 214 for clearing all selected modes and various set conditions, and a magnification setting key 216 for setting a copy magnification.

Further, the control panel 200 includes:
A paper size key 218 for selecting and setting the size of paper on which an image is to be formed, an automatic paper selection key 220 for detecting the size of a document placed on a platen and automatically setting the paper size, and setting a document size And an automatic magnification selection key 224 for automatically setting a copy magnification based on the paper size set by the paper size key 218 and the detected document size.

In addition to these various setting keys, an operation guide key 226 for displaying guidance information such as the contents of the set mode and operation procedure, a preheating key 228 for setting a preheating state, and a keypad for when the printer unit is operating. An interrupt key 230 for instructing an interrupt, a setting menu key 232 used for setting an input mode for inputting an original size for a universal mode for copying an irregular size original to the paper size, and a universal mode are provided. When set, the universal size key 234 for activating the universal mode, a universal mode valid display L indicating that the universal mode has been activated
An ED 236 and an enter key 238 for fixing the input numerical value as numerical data are provided.

At the center of the control panel 200, the state of the apparatus, the operation procedure, and various messages to the user are displayed in characters, graphics, or key patterns, and data from the user is displayed in a predetermined key pattern or graphics. A display panel 240 constituted by a touch panel type liquid crystal display device capable of input is provided.

Next, an operation of copying an image of a document by the copying apparatus shown in FIGS. 1 to 8 will be described. Device 2
Is turned on according to a control program stored in the ROM 102 when a main switch (not shown) is turned on, and forms an image corresponding to the supplied image data in response to a print request or facsimile reception from an external device. Initialized as possible. In this case, the control panel 20 shown in FIG.
For example, the display section of “0 is waiting for automatic reception. Please press the print key for copying. "

When the print key 210 of the control panel 200 is turned on after the document D to be copied is set on the document tray 72 of the automatic document feeder 6, the empty sensor 72a of the automatic document feeder 6 is turned on. Is checked, and after it is detected that a document is set on the document tray 72, the pickup roller 73 is driven by driving current supplied from the document feed control unit 164 to a document motor (not shown), and The lowermost document among the documents set on the tray 72 is
Guided to 4.

The document D guided by the paper feed roller 74 is further conveyed toward the aligning roller 75. Subsequently, when the leading end of the document D passes through the aligning sensor 75a, the clutch (not shown) is turned on by the aligning roller control unit 166, and the aligning roller 75 is stopped. As a result, the document D taken out of the document tray 72 via the pickup roller 73 is temporarily stopped, so that the inclination of the document D with respect to the document transport direction is corrected.

Next, a drive motor (not shown) is rotated under the control of the document transport control section 170, the belt roller 77 is rotated in the document feeding direction, and the transport belt 76 is rotated.
Further, at a predetermined timing, a clutch (not shown) is turned off and the aligning roller 75 is rotated again, so that the document D is fed from the aligning roller 75 to the transport belt 76.

Thereafter, the document D is conveyed onto the document table 10 of the copying machine 2 by rotating the conveyance belt 76 for a predetermined time by the conveyance motor. The transport belt 76 is stopped after a predetermined time, that is, a predetermined time determined by the interval between the aligning sensor 75a and the document guide 11, has passed since the rear end of the document D has passed through the aligning sensor 75a. No brake prevents rotation due to inertia.

On the other hand, when the leading edge of the document D is detected by the aligning sensor 75a,
PU 130 is notified that document D has been transported to a predetermined position, and then document D detected by document size detection circuit 172 via aligning sensor 75a.
The printer CPU 130 selects a cassette accommodating the paper P having the optimal size based on the size of the paper P and the copy magnification set from the control panel 200. Then, in accordance with the input copy magnification, the reading start position of the image data for inputting the image data from the CCD line sensor 24 to the page memory 321 is set in the ROM.
Called from 102 and stored in RAM 104. At this time, if the size of the paper P calculated by the printer CPU 130 based on the original size and the input copy magnification does not match the size of the image area defined based on the copy magnification, the size of the paper P Then, the reading start position, that is, the copyable document area is calculated based on the reference. In addition, the start position of writing on the photosensitive drum 30 by the laser exposure device 32 is similarly defined and stored in the RAM 104. At this time, if the size of the paper P calculated by the printer CPU 130 based on the original size and the input copy magnification does not match the size of the image area defined based on the copy magnification, the size of the paper P Then, the reading start position, that is, the copyable document area is calculated based on the reference. The writing start position on the photosensitive drum 30 by the laser exposure device 32 is also defined in the same manner.
04 is stored.

Since the upper limit of the size of the copyable document area is limited by the maximum size of the sheet that can be fed by the copying apparatus 2, the maximum size of the sheet that can be fed is limited to the maximum size. If “A3” is set, for example, even if the size of the document D is “B4” and 141% is input as the copy magnification, the size that can be actually copied is “A3”.
4 "size. Therefore, in this case, the reading start position is set to a position corresponding to the “A4” size.

Further, for example, a document D of "A4" size
If a copy magnification of 105% is input to
A cassette accommodating the “B4” size paper P is selected, and the reading start position of the “B4” size document including the displacement of the reading position corresponding to the copy magnification is set to the ROM 102 as the reading start position of the document D. Called from.

Separately, if a document D smaller than the "A4" size and larger than the "B5" size is set on the platen 10 and a copy magnification of 100% is selected,
The cassette containing the “A4” size paper P is selected, and the reading start position of the “A4” size document with the copy magnification of 100% is called from the ROM 104 as the reading start position of the document D.

If the original is of a non-standard size, the user presses the universal size key 234 of the control panel 200 shown in FIG. Enter the original size in mm units using the numeric keypad 208,
Confirm with the enter key 238. In this case, the maximum value in the main scanning direction that can be input with the ten keys is 297 mm
And the minimum value is 139 mm. This numeric keypad 208
Is temporarily stored in the RAM 104, and the NVM 10
6 can also be stored. When the universal mode key 234 is pressed to set the universal mode, the universal size valid display LED 236 indicating that the universal mode is set is turned on.

When a copy start is instructed by the print key 210 in a state where the universal mode is set, even if a document is supplied by using the automatic document feeder 6, the automatic document feeder 6 Without using the detected document size information, the length of the document in the main scanning direction, which is information of an atypical size that has been registered in advance (or input before the copy start instruction by the print key 210), that is, the document Using the width, ld and td are calculated.

Thereafter, as shown in FIG. 9, the read address of the line buffer memory is changed to ld so as not to read the image data before the pixel specified by ld.

The image data of the atypical document read as described above has the same format regardless of whether the document transport position is the center reference or the corner reference.

On the other hand, the exposure of the image on the photosensitive drum 30 by the laser exposure device 32 must be changed from the center to both ends in accordance with the sheet size so that the center of the photosensitive drum 30 is aligned with the center of the sheet. . Therefore, the range of the effective image data to be exposed is varied according to the paper size, and a position corresponding to the width is calculated by the horizontal synchronization signal and the number of synchronization clocks of the laser drive circuit according to the paper size to be used, and the time difference buffer buffer is used. The output timing to the control circuit will be changed.

In this case, the same processing can be applied regardless of whether the document transport position is the center reference or the corner reference. Next, the exposure lamp 12 of the first carriage 15 is turned on at a predetermined brightness, and the rotation of a pulse motor (not shown) causes the first carriage 15 to move the document D on the document table 10.
At a predetermined speed.

Subsequently, the image information of the document D placed on the document table 10 is reflected by the first mirror 14 of the first carriage 15 and reflected light generated by being illuminated by the exposure lamp 12 and the reflection plate 13. The light is sequentially reflected by the second mirror 21 and the third mirror 22 of the second carriage 20, passes through the imaging lens 23, and forms an image on the reading surface of the CCD sensor 24.

The image information of the document D formed on the CCD sensor 24, that is, the reflected light from the document D is transmitted to the CCD sensor 2.
4 after photoelectric conversion at a predetermined resolution by the RAM 1
The pixel is taken in order from a pixel at a predetermined position (not shown) of the CCD sensor 24 corresponding to the reading start position stored in the A / D converter 04, is converted into a digital signal by an A / D conversion circuit 181, and is converted into a resolution conversion circuit 182 and a shading correction circuit 1.
83, an image processing unit 313 including an image quality improvement circuit 184, a binarization circuit 185, and the like, given predetermined characteristics, and transferred to a predetermined area of the page memory 321 of the page memory unit 302 via the printer CPU 130. Is stored (stored).

In parallel with the start of supply of image information to the CCD sensor 24 or at a predetermined timing, the printer CPU
Under the control of 130, a motor drive voltage is supplied from the motor drive unit 132 to a motor (not shown), the motor (not shown) is rotated at a predetermined speed, and the photosensitive drum 30 is rotated at a desired speed. At the same time, a predetermined potential is applied from the charging device 31 to the surface of the photosensitive drum 30 by the high voltage output control unit 143. As an example, the initial surface potential supplied to the photosensitive drum 30 is set to approximately -650 volts.

The image data temporarily stored in the page memory 321 is exposed to a PLL signal returned from the polygon motor for rotating the polygonal mirror 32a of the laser exposure device 32 to the printer CPU 130 via the polygon motor control circuit 152. As a start signal, the modulation circuit 151
Thereby, the light intensity of the laser light emitted from the laser diode (not shown) of the laser exposure device 32 is intensity-modulated,
An electrostatic latent image is formed on the surface of the photosensitive drum 30. In addition,
The number of rotations of the polygon motor for rotating the polygonal mirror 32a is determined by the polygon motor control circuit 152 based on the resolution required for the image output from the apparatus body 4.
The rotation speed is set to an appropriate value.

The electrostatic latent image thus formed is developed by the high voltage output controller 143 with toner supplied from the developing roller 33a of the developing device 33 to which a developing bias voltage of, for example, -450 volts is applied. Then, similarly, the toner image is transferred onto the sheet P by the transfer and peeling device 34 to which a predetermined transfer voltage has been applied by the high-voltage output controller 143.

The toner image transferred onto the sheet P is separated from the surface of the photosensitive drum 30 together with the sheet P by a peeling output from the transfer peeling device 34 to which a predetermined peeling voltage is applied by the high voltage output controller 143. The sheet is conveyed to the fixing device 58 by the conveyance by the conveyance belt 57, and
8 is fixed on the sheet P.

The paper P on which the toner image has been fixed is transferred to the copying apparatus 2 via first and second discharge rollers 61 and 62.
The output tray 5 of the finisher 8 disposed outside the
9a.

The photosensitive drum 30 on which the toner image has been transferred onto the paper P is continuously rotated, and is exposed to light by a static elimination output from the pre-cleaning static eliminator 35 to which a predetermined pre-cleaning static elimination voltage is applied by the high voltage output controller 143. The charge of the residual toner remaining on the surface of the body drum 30 is removed,
Subsequently, the remaining toner is removed by the cleaning device 36, and the charge is further removed by the charge removing device 37, and subsequently used for the next image formation.

On the other hand, when all the image information of the first original D currently positioned on the original table 10 is supplied to the CCD sensor 24, the control of the original transport control unit 170 responding to the control of the printer CPU 130 Causes the transport belt 76 to rotate, so that the front and back of the document D are exchanged, or the next document D is fed. In other words, the transport motor is rotated by a drive current to a transport motor (not shown) under the control of the document transport control unit 170, the belt roller 77 is rotated in a predetermined direction, and the transport belt 76 is rotated.

Thus, when the original is a one-sided original, the first original currently set on the original platen 10 is conveyed toward the reversing roller 78, and the cover 71 is The document is discharged to a document receiving area formed at a predetermined position.

Subsequently, the empty sensor 72a
The presence or absence of the next original D is checked, and if the original D remains, the original feeding operation is repeated, and thereafter, the second original is set on the original platen 10 in the same manner as the first original. Then, the image information of the second document is read.

In this way, a series of image formation is repeated for all the documents D set on the document tray 72 of the automatic document feeder 6. FIG. 10 is a schematic diagram illustrating another example of a method of changing the image forming area for the non-standard size original described with reference to FIGS. 7 and 9.

In the method shown in FIG. 10, the length of the original in the main scanning direction (original width) and the width in the sub-scanning direction (original length) are determined by:
The format is set in mm units. The length and width are input using the numeric keypad 208, and the numeric data is determined by the enter key 238. The maximum value that can be input with the numeric keypad 208 is 297 mm in the main scanning direction, 430 mm in the sub-scanning direction, and the minimum value is 139 mm in the main scanning direction and 139 mm in the sub-scanning direction.
139 mm.

Thereafter, when the document is conveyed toward the document table 10 by the automatic document feeder 6, the size of the document is specified based on the time during which the aligning sensor 75a detects the document.

That is, the transport speed for transporting the original is h
If [mm / sec] is set, the original length L = h × tim [mm] when the original passage detection time detected by the aligning sensor 75a is tim.

Accordingly, while the automatic document feeder 6 conveys a document, document length information is obtained by a document conveying operation. Hereinafter, since the document is of an irregular size, the document size information detected by the automatic document feeder 6 is not used,
Using the width in the main scanning direction, which is information of an irregular size, which is registered in advance (or is input prior to the input of a copy start signal by the print key 210), ld and td
Is calculated.

However, the set size may be different from the direction of the document being actually conveyed (the direction in which the user sets the document). In this case, image displacement may occur even though the universal function is installed. There is a possibility that a problem may occur. For this reason, based on the flowchart shown in FIG. 11, it is determined whether or not the direction of the original being transported using the length information of the original detected by the automatic original feeder 6 matches the preset original transport direction. Is determined, and if they do not match, the set data in the main scanning direction and the length data in the sub-scanning direction are exchanged, and ld and td are replaced.
Is calculated.

Hereinafter, by specifying the read address of the line buffer memory to be equivalent to ld so as not to read the image data before the ld pixel, the image data of the atypical document read as described above is transferred to the document transporter. Regardless of whether the position is the center reference or the corner reference, the image data has the same format.

[0096]

As described above, according to the image forming apparatus of the present invention, the document conveyed by the automatic document feeder is an irregular document, and the document conveyance position is either center-based or corner-based. However, the image data of the atypical document is changed to image data of the same format. As a result, it is possible to prevent the original image from being displaced from the sheet or from missing part of the image. Therefore, undesired miscopy is suppressed, and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an image forming apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram schematically showing a control unit of the image forming apparatus shown in FIG.

FIG. 3 is a block diagram schematically showing a basic unit (main control unit) of the image forming apparatus shown in FIG. 1;

FIG. 4 is a block diagram schematically showing an image forming unit of the image forming apparatus shown in FIG.

FIG. 5 is a block diagram schematically showing a reading unit of the image forming apparatus shown in FIG.

6 is a block diagram schematically showing a facsimile unit of the image forming apparatus shown in FIG.

FIG. 7 is a schematic diagram showing a relationship between a document table and data in a line buffer in the image forming apparatus shown in FIGS. 1 to 6;

FIG. 8 is a schematic plan view showing an example of a control panel incorporated in the image forming apparatus shown in FIGS. 1 to 7;

FIG. 9 is a schematic diagram showing an effective image data range of image data stored in a line buffer memory in the image forming apparatus shown in FIGS. 1 to 8;

FIG. 10 is a flowchart showing an example of control for setting a length of a document in the main scanning direction (document width) and a width in the sub-scanning direction (document length), and then setting an effective image data range of image data.

FIG. 11 sets the length of the original in the main scanning direction (original width) and the width in the sub-scanning direction (original length), and then sets the effective image data range of the image data. 9 is a flowchart illustrating an example of control for preventing occurrence of a shift in an image data range.

[Explanation of symbols]

 2 laser exposure type copying apparatus (image forming apparatus), 4 apparatus main body, 6 automatic document feeder, 8 finisher, 10 document table, 11 document guide, 12 exposure lamp, 23 imaging lens, 24 ... CCD sensor, 30 ... Photoconductor drum (image carrier), 31 ... Charging device, 32 ... Laser exposure device, 32a ... Polygon motor, 33 ... Developing device, 34 ... Transfer peeling device, 35 ... Electrification device before cleaning, DESCRIPTION OF SYMBOLS 36 ... Cleaning device, 37 ... Static eliminator, 100 ... System CPU, 102 ... ROM, 104 ... RAM, 130 ... Printer CPU, 140 ... Sensor input part, 146 ... Transport control part, 150 ... Laser drive circuit, 151 ... Modulation circuit .., 152... Polygon motor control circuit, 164. Controller control section, 170: document transport control section, 172: document size detection circuit, 174: sensor input section, 200: control panel, 226: operation guide key, 232: setting menu key, 234: universal size key, 236 ... Universal mode valid display LED, 240: display panel, 301: basic unit, 302: page memory unit, 311: main control unit, 312: facsimile, 313: image processing unit.

Claims (12)

[Claims] An image reading apparatus reads an image of a target area by changing a starting point of an effective reading area according to a size of the original. Reading means for performing scanning; input means for setting and inputting a document placed on the platen as an arbitrary size; and reading means based on the size of the document input by the input means. Control means for changing the start point of the effective reading area to perform scanning. 2. An original plate on which an original is placed, and reading of an image in a target region of the original placed on the original plate by changing a starting point of a read effective area according to the size of the original. Reading means for performing scanning to generate continuous image data; storage means for storing image data generated by the reading means; and setting and inputting an original placed on the platen as an arbitrary size Input means, based on the size of the document input by the input means, to change the start point of the image data stored in the storage means to change the start point of the effective reading area for the reading means; Control means for outputting image data by changing the image data. 3. A document table on which a document is placed, and an image of a target area is read from the document placed on the document table by changing a start point of an effective reading area according to the size of the document. Reading means for performing scanning to generate continuous image data; storage means for storing image data generated by the reading means; and setting and inputting an original placed on the platen as an arbitrary size Input means, based on the size of the document input by the input means, to change the read end position of the image data stored in the storage means in order to change the end point of the effective read area for the reading means. Control means for outputting image data by changing the image data. 4. A document table on which a document is placed, and an image reading operation is performed by scanning the document placed on the document table in a main scanning direction and a sub-scanning direction. Reading means for changing the effective reading area in the main scanning direction and the sub-scanning direction according to the size of the original to perform scanning for reading an image in the target area; and the main scanning direction of the original placed on the original platen. Input means for setting and inputting the size along the sub-scanning direction as an arbitrary size; and changing the effective reading area for the reading means based on the size of the document input by the input means. An image reading apparatus, comprising: a control unit for reading and scanning. 5. A document table on which a document is placed, an automatic document feeder for automatically feeding a document from a predetermined position to the document table, and a document using the automatic document feeder. When feeding the document to the platen, the start and end points of the effective reading area are changed according to the size of the document to scan the image in the target area, and the document is scanned without using the automatic document feeder. Reading means for reading the image of the target area by changing the start point of the effective reading area without changing the start point regardless of the size of the original; Input means for setting and inputting the original to be arbitrarily sized, and when the automatic document feeder is used for the reading means based on the size of the original input by the input means, Change the start and end points of the area, and An image reading apparatus, comprising: a control unit for performing scanning by changing the end point without changing the start point of the effective reading area when using the automatic document feeder. 6. A document table on which a document is placed, and an image of a target area is read by changing a starting point of a reading effective area according to the size of the document on the document placed on the document table. Reading means for performing scanning; input means for setting and inputting a document placed on the platen as an arbitrary size; and reading means based on the size of the document input by the input means. Control means for changing the starting point of the effective reading area to perform scanning, and image forming means for forming an image on an image carrier in accordance with an image read by the reading means under the control of the control means. Characteristic image forming apparatus. 7. A document table on which a document is placed, and reading of an image in a target area of the document placed on the document table by changing a starting point of a reading effective area according to the size of the document. Reading means for performing scanning to generate continuous image data; storage means for storing image data generated by the reading means; and setting and inputting an original placed on the platen as an arbitrary size Input means, based on the size of the document input by the input means, to change the start point of the image data stored in the storage means to change the start point of the effective reading area for the reading means; An image forming apparatus comprising: control means for changing and outputting image data; and image forming means for forming an image on an image carrier in accordance with an image read by the reading means under the control of the control means. 8. A document table on which a document is placed, and an image of a target area is read from the document placed on the document table by changing a starting point of a reading effective area according to the size of the document. Reading means for performing scanning to generate continuous image data; storage means for storing image data generated by the reading means; and setting and inputting an original placed on the platen as an arbitrary size Input means, based on the size of the document input by the input means, to change the read end position of the image data stored in the storage means in order to change the end point of the effective read area for the reading means. An image forming apparatus comprising: control means for changing and outputting image data; and image forming means for forming an image on an image carrier in accordance with an image read by the reading means under the control of the control means. 9. A document table on which a document is placed, and an image reading operation is performed by scanning the document placed on the document table in a main scanning direction and a sub-scanning direction. Reading means for changing the effective reading area in the main scanning direction and the sub-scanning direction according to the size of the original to perform scanning for reading an image in the target area; and the main scanning direction of the original placed on the original platen. Input means for setting and inputting the size along the sub-scanning direction as an arbitrary size; and changing the effective reading area for the reading means based on the size of the document input by the input means. An image forming apparatus, comprising: a control unit for reading and scanning; and an image forming unit for forming an image on an image carrier in accordance with an image read by the reading unit based on the control of the control unit. 10. A document table on which a document is placed, an automatic document feeding means for automatically feeding a document from a predetermined position to the document table, and a document using the automatic document feeding means. When feeding the document to the platen, the start and end points of the effective reading area are changed according to the size of the document to scan the image in the target area, and the document is scanned without using the automatic document feeder. Reading means for reading the image of the target area by changing the start point of the effective reading area without changing the start point regardless of the size of the original; Input means for setting and inputting the original to be arbitrarily sized, and when the automatic document feeder is used for the reading means based on the size of the original input by the input means, Change the start and end points of the area In the case of using the automatic document feeder, control means for changing the end point without changing the start point of the effective reading area and performing scanning by scanning; and an image read by the reading means based on the control of the control means. And an image forming means for forming an image on an image carrier according to the following. 11. The reading means includes: an exposing means for performing line-shaped exposure scanning; and an exposure length changing means for changing the line-shaped exposure scanning length of the exposing means in accordance with a change in the effective reading area. The image reading apparatus according to claim 1, wherein: 12. The reading means includes: an exposure means for performing a line-shaped exposure scan; and an exposure length changing means for changing a line-shaped exposure scan length of the exposure means in accordance with a change in a read effective area. The image forming apparatus according to claim 6, wherein: