JP2620802B2 - Image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus such as a copying machine, and more particularly to an image forming apparatus having a continuous shooting function.

(Prior Art) Conventionally, in this type of apparatus, the potential of a charger for charging a photoreceptor is changed to form a top margin on transfer paper, and a lamp for forming a top margin is omitted to eliminate the periphery of the photosensitive drum. There is known one that simplifies. In such an apparatus, for example, the leading end margin is formed as shown in FIG. That is, the photosensitive drum 100
At a position separated from the photosensitive position R by a distance l
101 while placing it on the opposite side of the scanning direction from the original The document scanning position detection sensor 102 is arranged at an interval of, and it is assumed that the scanning speed has already reached a predetermined scanning speed when passing through the sensor 102 from the scanning optical system. The scanning optical system is moved without discharging the charger 101 for a predetermined time or distance, and when the scanning optical system reaches the image destination, the charger 101 is discharged to form a tip margin of about 2 mm. I do.

In this case, in an apparatus that performs continuous copying of an original, when forming the leading edge margin on the second surface, the setting conditions in a common adjustment unit such as a timer are used based on the signal obtained by the sensor 102. By performing the same scanning and discharging as the first surface by changing the above, an appropriate margin is formed at the tip of the second surface.

(Problems to be Solved by the Invention) In recent years, a small-diameter photosensitive drum is often used in order to reduce the size of the apparatus. However, when a small-diameter photosensitive drum is used, an image is formed. Means must be closely arranged around the drum.

However, in such a conventional example, in order to form the leading end margin at the time of continuous shooting based on the signal obtained by the same detection sensor 102, the distance between the charger 101 and the exposure position R and the detection sensor 102 And the distance between the image destination position P is constant As a result, the charger 101 cannot be brought sufficiently close to the exposure position, and a small-diameter photosensitive drum in which the respective units are densely arranged cannot be used. Furthermore, since the detection sensor 102 is disposed at a position where the moving speed of the scanning optical system should be constant, the distance from the start of the movement of the scanning optical system to the arrival at the image destination is long, and the driving time , And the speed of image formation cannot be increased.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to reduce the size of the apparatus by using a small-diameter photoreceptor and quickly perform continuous image formation. It is an object of the present invention to provide an image forming apparatus capable of performing such operations.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a scanning optical system having a different moving speed according to a copy magnification and a plurality of originals are continuously scanned by the scanning optical system. To expose the photoconductor,
A continuous shooting function for selectively forming an image corresponding to each document;
An image forming apparatus having a function of forming a non-image area on each of the images on the photoconductor by controlling a charging unit in synchronization with the scanning optical system. The timing of controlling the charging unit to form an image area is defined as time information of the scanning optical system including time from the start of the movement of the scanning optical system to the time when the scanning optical system starts moving and reaches a predetermined scanning speed. , And are set corresponding to each document.

(Operation) In the present invention having the above configuration, the timing for controlling the charging means for forming a non-image area in an image corresponding to each document is set from the start of the movement of the scanning optical system. Based on the time information of the scanning optical system including the time from the start of the movement to the time when the scanning speed reaches the predetermined scanning speed, each is set corresponding to each document and a non-image area is formed in each image. Therefore, the position of the charging means and the position of the means for detecting the charging criterion are not limited as in the case where the charging criterion is the same.

Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the image forming apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a document placing glass on which a document is placed, which is provided on an upper portion of the apparatus main body. L is a document illumination lamp that scans the document, and is unitized together with a reflection mirror 2 that reflects document image light. Reference numerals 3 and 4 denote reflection mirrors for guiding the image light reflected by the reflection mirror 2 to the imaging lens 5, which are incorporated in the mirror unit at an angle of 90 ° to each other. The imaging lens 5 is a zoom lens, driven by a pulse motor M that drives an optical system,
Magnification copying of the original image is performed. In addition, 6,7
Reference numerals 8 denote reflection mirrors for guiding image light formed by the imaging lens 5 to a photosensitive drum 9 as an image carrier. S is a sensor for detecting the home position of the optical system.

Around the photosensitive drum 9, means for forming an image by a known electrophotographic method are provided at respective positions. That is, reference numeral 10 denotes a primary charger for uniformly charging the surface of the photosensitive drum, and has a grid 10a capable of adjusting a charged voltage. 11 denotes a latent image formed on the drum 9 by a developer such as toner. A transfer unit for transferring the toner image onto transfer paper S as a transfer material; a cleaning unit for removing toner remaining on the surface of the drum 9; This is a pre-exposure lamp for removing static electricity.

Below the photosensitive drum 9, a cassette 15 containing transfer paper of a predetermined size can be inserted. In the vicinity thereof, a switch 16 for detecting the presence or absence of transfer paper in the cassette 15 when the cassette is inserted, and a switch group 17 as detection means for detecting the size of the cassette 15, that is, the size of the transfer paper.
Are provided. Reference numeral 18 denotes a pickup roller for sending out the transfer paper, reference numerals 19 and 20 denote paper feed rollers for transporting the transfer paper via a transfer paper guide 21, and reference numeral 22 denotes a registration roller for feeding the transfer paper to the transfer unit at a predetermined timing. In this embodiment, a manual feed guide 23 is provided in the vicinity of the registration roller 22 so that the transfer paper can be fed manually.

Reference numeral 26 denotes a transport unit that transports the transferred transfer paper to the fixing unit 27. The fixing unit 27 includes a fixing unit including a heat roller and a pressing roller, and further includes a paper discharge roller 30 that discharges the fixed transfer paper onto a paper discharge tray 31.

In the above configuration, when performing image formation, first, the document illumination lamp L is stopped at a position detected by the home position sensor S, more specifically, at a position where the document illumination lamp L is moved backward by a predetermined distance from the position detected by the home position sensor S. ing. When the scanning of the original is started, the pulse motor M, which is the driving source of the optical system, moves in the direction in which the optical system moves forward (rightward in the drawing) until the driving pulse rate corresponding to the selected magnification value is reached. So-called slow-up control in which the pulse rate gradually increases is performed. That is, the moving speed of the document illumination lamp L is gradually accelerated and reaches the target position. Thereafter, the optical system is scanned at a predetermined speed, and the light image of the document is guided to the photosensitive drum 9 via the mirrors 2, 3, and 4, the imaging lens 5, and the mirrors 6 and 7.

On the other hand, since the surface of the photosensitive drum 9 is uniformly charged by the primary charger 10 and is rotating in the direction of the arrow, a latent image corresponding to the original image is sequentially formed on the surface of the drum 9, and this latent image is developed. The image is visualized by the unit 11 as a toner image. Then, the toner image is transferred onto the transfer paper by the operation of the transfer charger 12. In this case, the transfer papers stacked in the cassette 15 are taken out one by one from the top by the pickup roller 18 and moved to the transfer position by the paper feed rollers 19 and 20 and the registration roller 22 along the transfer paper guide 21. Further, the transfer paper having received the transfer of the toner image by the transfer charger 12 is transported by the transport unit 26 to the fixing unit 27 and undergoes image fixing. Thereafter, the transfer paper having undergone the fixing is discharged by a discharge roller 30, and the discharge tray
It is placed on 31.

Also, when performing copying by hand,
When the transfer paper is placed thereon and inserted to the paper feed sensor 25, the transfer paper is fed to the transfer unit by the paper feed roller 20, and then the original image is transferred through the above-described process.

Next, a method of forming a margin at the leading end of an image and a method of aligning the leading end with a transfer sheet will be described with reference to FIG.

As a means for preventing toner adhesion in a non-image area, a static elimination means using a light source such as an LED lamp or a fuse lamp is generally used, but in this embodiment, a voltage value of a grid 10a provided in the primary charger 10 is controlled. As a result, the photosensitive drum 9 is neutralized. This is because the number of members around the photosensitive drum 9 is reduced, and a smaller-diameter photosensitive drum can be used. However, in this case, the exposure point R of the photosensitive drum 9 and the grid of the charger 10
The distance A from the home position sensor S cannot be set sufficiently short as compared with the distance B between the home position sensor S and the original contact position, that is, the image destination. After a predetermined period of time according to the magnification selection value from the start of the movement, the voltage of the grit 10a is switched from a low level to a predetermined voltage, thereby forming a 2 mm margin at the leading end of the document.

On the other hand, when the leading edge margin formed on the photosensitive drum 9 in this manner is adjusted to the transfer paper, the exposure point R and the transfer portion Q
Is shorter than the distance D between the registration roller 22 and the transfer section, the image forming apparatus waits at the position of the registration roller 22 before the image at the leading end of the document is actually exposed on the photosensitive drum 9. It is necessary to re-feed the transfer material and feed it toward the transfer section.

Therefore, in the present embodiment, the leading edge of the image is aligned with the transfer paper as follows. That is, first, when the document illumination lamp L starts to move, moves by the distance E, and reaches the target speed, it is detected by the home position sensor S. The value obtained by dividing the value of the distance B + 2 mm from the timing at which the light passed through the home position sensor S by the speed according to the selected magnification is used. This time is defined as x. Also, a registration roller
The value obtained by subtracting the time required for the image at the exposure point R of the photosensitive drum 9 to reach the transfer portion from the time from the start of refeeding to the time at which the transfer sheet reaches the transfer portion is defined as y, and
Time required to feed the transfer paper by 2mm (2mm ÷ 100mm / s = 0.0
Add 2 sec, but the transport speed = 100 mm / s (Equation (1)).

x- (y + 0.02) = Z (sec) (1) That is, the registration roller 22 is moved at the timing when the above Z seconds have passed since the passage through the home position sensor S.
Is operated, and re-feeding is performed, whereby a transfer paper image having a margin of 2 mm can be obtained according to the selected magnification.

The scanning distance of the optical system having the lamp L and the like is set to a predetermined distance according to cassette size data, magnification data, and the like.
When the vehicle reaches the target position, it performs slowdown control and stops, and then performs slowup control and constant speed control again in the direction of the home position sensor S to move backward. Then, when the home position sensor S is detected, slowdown control is performed, and the motor is stopped at a predetermined position regardless of the selected magnification.

Next, a description will be given in detail of the leading edge margin control at the time of continuous page shooting with reference to the block diagram of FIG. 3 and the flowchart of FIG.

First, in steps S1 to S3 (the number of steps, the same applies hereinafter), when the apparatus is powered on, the apparatus enters a standby state in which image formation can be performed unless there is a copy prohibition condition, and a copy start signal for performing continuous shooting is input. Starts the page continuous copying process. In this case, when the set number of copies is “n”, the first side is copied n times and then the second side is copied n times.

Next, in S4 to S11, when the document scanning system drive timing has been reached, the microcomputer MC outputs an excitation pattern to the pulse motor drive circuit 40, and rotates the pulse motor M to move the optical system. Table at this timing
4 based on the charge-charge ON timer data and the data of the front-end margin adjustment volume shown in FIG.
Start timer T1 to activate. The charged charge ON timer data is stored in advance in the ROM of the microcomputer MC as data according to the following logic. The pulse motor M is driven by the microcomputer MC under slow-up control.
When this control is completed, an excitation pattern having a constant frequency corresponding to the copy magnification is output, and the optical system is scanned at a constant speed.

Tables 1 to 3 are data tables stored in the ROM of the microcomputer, and Table 1 is a table of excitation pattern output frequencies at the time of slow-up.
Perform slow-up from o.1 to the table number specified by the copy magnification. Table 2 shows the original scanning speed data.
Predetermined data corresponding to the copy magnification is selected. Table-3
Is a slow-up end table number corresponding to the copy magnification.

For example, if the distance from the drive start position of the exposure unit to the image tip is 24 mm and the exposure unit moves 0.12 mm when the pulse motor M rotates 1 step, the original scanning system drive timing Table 3 shows that the slow-up end table No. has a copy magnification of 100%.
In this case, a value of “15” is obtained. That is, the moving distance of the exposure unit during the slow-up is 15 (step) × 0.12 (m
m) = 1.8 (mm), and the time required during that time is 28.5 [ms] obtained by adding Table Nos. 1 to 15 in Table 1. After completion of the slow-up, an excitation pattern is output based on the frequencies shown in Table-2. For example, if the copy magnification is 10
When it is 0%, the excitation pattern is sequentially output every 1.2 [mS]. Therefore, the time from the end of the slow-up to the arrival at the image destination is {(24−1.8) /0.12} × 1.2 [ms] = 222 [m
S]. As a result, when the copy magnification is 100%, the time from when the pulse motor M is driven to when the exposure unit reaches the image destination is (28.5 + 222) = 250.2 [ms].
Assuming that the time required for the charged position charged on the photosensitive drum by the primary charger 10 shown in FIG. 2 to reach the exposure point R due to the rotation of the photosensitive drum 9 is x, as described above, Time minus this x (28.5 + 22
2) By operating the charger 10 at -x [mS] (Table 4) via the high-voltage unit 41, it is possible to obtain a proper leading margin when copying the first side. This time x can be arbitrarily set based on the data of the front end margin adjustment of the first surface. Tables obtained in the same manner also for other copy magnifications
Activate the timer T1 and the charger 10 according to the data of 4.
Form the top margin of the face.

Next, according to the procedures shown in S6, S12, and S13, the copying of the second side is performed after the copying of the first side is completed. In this case, when the original scanning system drive timing is reached, the exposure unit is moved in the same manner as when copying the first side. Then, immediately after the exposure unit has passed the home position sensor S, the timer T2 is operated. The timer T2 activates the charger 10 after a predetermined time based on the data of the margin adjustment signal on the second side including the cassette size, the copy magnification, and the volume. still,
It is assumed that the exposure unit completes the slow-up before reaching the home position sensor and moves at a constant speed.

Thereafter, the copying process is performed, and when the copying of the second side is completed, S2
To return to the standby state.

(Effects of the Invention) In the present invention having the above-described configuration and operation, the timing for controlling the charging means to form a non-image area in an image corresponding to each document is determined from the start of movement of the scanning optical system. Based on time information of the scanning optical system including the time from the start of movement of the scanning optical system to the time when the scanning optical system reaches a predetermined scanning speed, by controlling the charging potential of the photosensitive member at the time of scanning each document, Since the position can be selected arbitrarily and a small-diameter photoconductor can be used,
The size of the device can be reduced.

In addition, since the non-image area can be formed separately according to the original, if the formation of one non-image area is started simultaneously with the original scanning, the original scanning distance can be shortened, and the image forming time can be shortened. Can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an explanatory view showing the principle of forming a leading end margin and aligning the leading end with a transfer sheet in the embodiment. 3
FIG. 4 is a block diagram showing a control system relating to the formation of the leading edge margin of the embodiment, FIG. 4 is a flowchart showing the procedure of forming the leading edge margin of the embodiment, and FIG. 5 is an explanatory diagram showing a conventional method of forming the leading edge margin. is there. DESCRIPTION OF SYMBOLS 1... Original table 9... Photosensitive drum (image carrier) 10... Primary charger, 10 a. Grid L... Original illumination lamp, M... Pulse motor MC. Position sensor T1, T2 …… Timer

Continuation of front page (56) References JP-A-61-215565 (JP, A) JP-A-50-137746 (JP, A) JP-A-62-27766 (JP, A)

Claims (1)

(57) [Claims] A scanning optical system having different moving speeds according to a copying magnification and a plurality of originals are successively scanned by a scanning optical system to expose a photosensitive member to selectively form an image corresponding to each original. An image forming apparatus having a function of forming a non-image area on each of the images on the photoconductor by controlling a charging unit in synchronization with the scanning optical system. Correspondingly, the timing for controlling the charging means to form a non-image area on an image includes a time from the start of the movement of the scanning optical system to the time from the start of the movement of the scanning optical system to a predetermined scanning speed. An image forming apparatus, wherein the image forming apparatus is set for each document based on time information of a scanning optical system.