JPH0363071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning copying machine, and more particularly to a scanning time control device for the copying machine.

In a scanning copying machine, if the document is of a specified size, such as B5, A4, B4, A3, etc., the carriage of the scanning optical system is required to scan the document of the specified size from the exposure reference position of the platen. The robot is moved at a predetermined speed for a certain amount of time. This is preferable because the necessary scanning area can be accurately scanned, but in the case of originals of a size other than the specified size, such as postcards, it takes a long time to scan and has the disadvantage that unnecessary parts are scanned.

In addition to the above-mentioned apparatus, there is also known an apparatus that uses a paper sensor provided in a copy paper feeding path to detect passage of copy paper, and moves a scanning optical system for a predetermined period of time after this detection. This method is simple in that it does not require an exposure reference point on the platen, but it has the disadvantage that the position of the image on the copy paper is not accurate because the position of the document on the platen is not accurately known.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that can accurately scan originals of a specified size, and can also be applied to originals of special sizes without waste. An object of the present invention is to provide an image forming apparatus that does not perform extra scanning even when using paper.

In order to achieve this objective, according to the present invention,
A scanning type image forming apparatus that scans an original image on a moving latent image carrier to form an electrostatic latent image, develops the electrostatic latent image, and transfers it to copy paper, and the image forming device From the carrier movement time t ₂ required for the latent image carrier to move the paper detecting means for detecting the edge from the original image scanning start position to the transfer position, the leading edge of the copy paper moves from the paper detection position of the paper detecting means to the transfer position. The paper is arranged so that the paper movement time t ₁ required to move the paper is long, and the paper movement time t ₁ and the carrier movement time are changed after the paper detection means detects the leading edge of the paper.
After the difference time t ₃ from t ₂ has elapsed, scanning of the original image is started, and after the difference time t ₃ has elapsed since the paper detection means detects the trailing edge of the paper, the scan control means ends the scanning of the original image. An image forming apparatus is provided.

Further, according to the present invention, there is also provided an image forming apparatus that detects the trailing edge of the paper instead of detecting the leading edge of the paper and scans the paper without waste. That is, according to the present invention, the paper detecting means for detecting the leading and trailing edges of the copy paper is determined based on the carrier movement time t ₂ required for the latent image carrier to move from the original image scanning start position to the transfer position. The paper is arranged so that the paper movement time _{t 1} required for the leading edge of the paper to move from the paper detection position of the paper detection means to the transfer position is long, and the paper movement time t ₁ from the time when the paper detection means detects the trailing edge of the paper to the transfer position is increased. Support moving time t ₂
and the difference time t ₁ − _{t 2} obtained by subtracting the paper passing time t ₄ required for the copy paper to pass through the paper detection means.
An image forming apparatus is provided, characterized in that it includes a scanning control means that starts scanning the original image after the elapse of _-t4 and ends the scanning of the original image after the elapse of the paper passing time _t4 .

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, an original 2 is placed on a platen 1, the placed original 2 is irradiated by a lamp 3, and a reflected light image from the original 2 is transmitted via mirrors 4 to 7 (as required). (A lens may be provided if necessary) The image is projected onto the image forming position A of the photoreceptor 9 rotating in the direction of the arrow. A corona charger 8 is provided on the photoreceptor 9 upstream of the imaging position A, and uniformly charges the surface of the photoreceptor 9 to impart photosensitivity. Therefore, when an optical image is projected at the imaging position A, an electrostatic latent image is formed on the surface of the photoreceptor 9. This image is developed by a developing device 10, and the developed toner image is moved to a transfer position B.

Copy paper 11 is fed on feeding path 12 at a speed synchronized with the surface speed of photoreceptor 9. Note that a paper sensor 13 is provided in the feeding path 12 so that the paper is aligned with the toner image. At the transfer position B, the toner image on the surface of the photoreceptor is transferred onto the paper 11 with the help of the transfer corona discharger 14 . After the transfer, the copy paper 11 passes through a fixing device (not shown), the toner image is fixed on the paper, and the copy is output as a copy. On the other hand, the photoreceptor 9 is provided with a cleaning device 15 downstream of the transfer position B, and the toner and latent image remaining on the surface of the photoreceptor are neutralized and cleaned in preparation for the next image formation. The above is a general description of a copying machine and should be sufficient for understanding the present invention.

There are two types of scanning copying machines: one in which an optical system such as a lamp, a mirror, or a lens is moved relative to a document on a fixed platen, and the other in which the optical system is fixed and the platen is moved. Although the present invention can be applied to any type of copying machine, for convenience of explanation, a scanning copying machine using a moving optical system will be described.

In the copying machine shown in FIG. 1, a lamp 3 and a mirror 4 are supported by a carriage 16, which moves in the direction of the arrow at a speed synchronized with the surface speed of the photoreceptor 9. This movement is controlled by a scanning time control device 17 according to the invention, which is connected to the main control section 18 of the copying machine. Further, a sensor 19 is provided on the lower surface of the platen 1 to define an exposure reference point C, and this position C also serves as a position where the edges of the original 2 are aligned. The output of the sensor 19 is input to the control device 17, and the lamp 3 starts emitting light, that is, scanning of the document for exposure is started. Further, in the present invention, a signal indicating the passage of copy paper 11 from copy paper sensor 13 is inputted not only to main control section 18 of the copying machine but also to control device 17.

To explain the operation of the carriage 16, a document of a specified size, such as B5, A4, etc., is placed on the platen 1.
When a B4 or A3 size document is placed, a predetermined size is specified on the operation panel (not shown) of the copying machine. In response to this size specification, a size specification signal is sent from the copying machine control section 18 to the control device 17, and the scanning time T corresponding to the specified size is calculated by the device 17. By pressing the start switch (not shown) of the copying machine, the controller 17 moves the carriage 16 at a predetermined speed in the direction of the arrow, and when the exposure reference point C is reached, the device 17 is activated by a signal from the sensor 19 to move the carriage 16 to the lamp 3. lights up and scanning of the original begins. After scanning has been performed for the calculated time T, the carriage 16 quickly returns to its original or home position. In addition, in this scanning, it is possible to scan an extra time α, thereby completely covering the document surface.

Next, if an original of a special size other than the standard size, such as a postcard, is placed on platen 1, scanning the standard size will require extra scanning, image formation, transfer, cleaning, etc. Undesirable. In response to this, the present invention employs a method different from the above-described scanning method when making copies from such special-sized originals. Briefly, the start of document scanning and the scanning time are determined by signals from paper sensor 13 on copy paper feed path 12. An example of this will be explained below.

Assume that a postcard is placed as an original on the platen 1, the copy paper is a postcard, etc., and a special size copy is specified from the operation panel of the copying machine. When the start switch is pressed, copy paper feeding begins, but the carriage 16 does not move. Next, when the copy paper reaches the paper sensor 13 and energizes the sensor, this is communicated not only to the copier main control section 18 but also to the scanning time control device 17. Upon receiving this signal, the control device 17 calculates the time _t1 required for the copy paper being fed at a predetermined speed to be sent from the sensor 13 to the transfer position B, and the time t1 required for the photoreceptor surface to move from the image forming position A to the transfer position A at the predetermined speed. The time _t2 required to move to transfer position B is calculated, and the time difference obtained by subtracting time _t2 from time _t1 is calculated.
t ₃ is calculated. Controller 17 controls carriage 16 such that when time t ₃ has elapsed after the copy paper reaches sensor 13, carriage 16 begins scanning the document (i.e., postcard) on the platen. The scanning period of the carriage 16 is set to be approximately equal to the period during which the copy paper passes the sensor 13. That is, scanning of the carriage 16 starts when time _t3 has elapsed after the leading edge of the paper reaches the sensor 13, and the copy paper reaches the sensor 13.
The carriage 16 finishes scanning the document after a time _t3 has elapsed since the trailing edge of the copy paper finished passing the sensor 13. Since the copy paper is the size that corresponds to the original, carry 1
The scanning time of No. 6 becomes appropriate, and unnecessary scanning etc. are completely eliminated.

Further, although the delay time of the scanning time is calculated based on the time when the copy paper reaches the sensor 13, the scan start time can also be determined based on the time when the copy paper finishes passing the sensor 13. In this case as well, it is necessary that the time t ₁ is equal to or longer than the time t ₂ plus the time t ₄ at which the copy sheet has passed.

FIG. 2 is a flowchart of the scanning operation by the scanning time control scan 17. As is clear from this figure, when the document is of a specified size such as B5, A4, B4, A3, etc., the control device 17 calculates the scanning time corresponding to each size, and adjusts the carriage 1 accordingly.
6 and scan the original for a predetermined time from the exposure reference point C, the carriage 16 is returned to the home position. If the document is of a special size, the start of scanning by the carriage 16 is delayed for a predetermined period of time, the document is then scanned for a period corresponding to the size of the document, and after the scanning is returned to the home position.

Therefore, according to the present invention, when a specified size copy is specified, the image position on the copy paper is accurately copied, and when a special size copy is specified, there is no waste such as scanning unnecessary parts. There is no need to worry about this, and copies of any size can be created properly.

Furthermore, scanning of the original is started after time _t3 has elapsed since the leading edge of the copy paper passes the sensor, and scanning of the document is ended after time _t3 has elapsed since the trailing edge of the copy paper has passed the sensor. , the scanning period can be controlled based on the length of the copy paper in the traveling direction, and even if the copy paper size is different, there is no need to perform extra scanning beyond the copy paper size, and the number of copies per unit time is reduced. It is possible to increase the number of sheets. Further, according to the present invention, after the trailing edge of the paper passes the sensor, a difference time t ₁ −t ₂ −t ₄ elapses, which is obtained by subtracting the carrier movement time t ₂ and the paper passage time t ₄ from the paper movement time t ₁ . Even with a configuration in which scanning of the original is started later and completed after the paper passing time _t4 has elapsed, unnecessary scanning is not performed, regardless of the difference in copy paper size, and the amount of time required per unit time is reduced. The number of copies can be increased.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a scanning copying machine to which the present invention is applied, and FIG. 2 is a flowchart of a scanning operation performed by the control device of the present invention. 1...platen, 2...original, 3...lamp, 4,
5, 6, 7...Mirror, 9...Photoconductor, 10...Developer, 11...Copy paper, 12...Feed path, 13...Paper sensor, 15...Cleaner, 16...Carriage, 1
7...Scanning time control device, 18...Copier main control section,
A...Image formation position, B...Transfer position, C...Exposure reference position.

Claims (1)

[Scope of Claims] 1. A scanning image forming apparatus that scans an original image on a moving latent image carrier to form an electrostatic latent image, develops the electrostatic latent image, and transfers it to copy paper, comprising: Based on the carrier movement time _t2 required for the latent image carrier to move from the original image scanning start position to the transfer position, the leading edge of the copy paper is detected by the paper detection means that detects the leading and trailing edges of the paper. The paper is arranged so that the paper movement time t ₁ required to move from the paper detection position to the transfer position is long, and the paper movement time t ₁ and carrier movement time t ₂ are changed after the paper detection means detects the leading edge of the paper. The difference time t ₃
The method is characterized by comprising a scan control means that starts scanning the original image after the elapse of time, and ends the scanning of the original image after the difference time _t3 has elapsed since the sheet detecting means detects the trailing edge of the sheet. image forming device. 2. In a scanning image forming apparatus that scans an original image on a moving latent image carrier to form an electrostatic latent image, develops the electrostatic latent image, and transfers it to copy paper, the leading and trailing edges of the copy paper From the carrier movement time _t2 required for the latent image carrier to move from the original image scanning start position to the transfer position, the leading edge of the copy paper moves from the paper detection position of the paper detection unit to the transfer position. The paper is arranged so that the paper movement time t ₁ required to move the copy paper is long, and the paper detection means detects the trailing edge of the paper, and then the paper movement time t ₁ and the carrier movement time t ₂ and the copy paper is detected. After the difference time t ₁ − _{t 2} − _{t 4} has elapsed by subtracting the paper passage time t ₄ required to pass through the means,
An image forming apparatus characterized by comprising a scan control means that starts scanning an original image and ends scanning of the original image after the paper passing time _t4 has elapsed.