JPS5926956B2 - Multiple transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a multiple transfer device, such as color copying, which sequentially forms a multicolor developed image on a photoreceptor and transfers the multicolor developed image to a transfer member.

In transfer type copying apparatuses, a configuration is generally used in which a transfer roll holding a transfer material is brought into contact with a drum-shaped photoreceptor. The transfer method to this transfer material is 1.
A method in which a high voltage is applied to the photosensitive drum in advance using a post charger, and the transfer material is passed between the grounded transfer roll and the drum. 2 or a method of applying a high potential of opposite polarity to the toner to the transfer roll (bias transfer) is common.

The apparatus of the above type can be effectively used in color copying apparatuses in particular because positioning can be easily performed during transfer.

However, if the alignment is misaligned due to a paper feeding error, the time loss is significant because color reproduction requires three to four times as much transfer time as monochrome copying. Further, in such a case, the toner on the photosensitive drum is transferred to a portion where there is no transfer material, resulting in staining of the transfer roll. Moreover, since this type of roll is generally made of an elastic material such as rubber, it is extremely difficult to clean it. In view of the above points, the present invention provides a multi-transfer device that achieves good control during transfer, eliminates device contamination due to malfunction, and eliminates wasted operating time of the device.

The present invention, which achieves the above object, forms electrostatic latent images corresponding to each color component on a photoreceptor, develops each latent image with a corresponding color developer, and transfers each developed image to a transfer material. In a multi-transfer device that obtains a multicolor image by repeating a step of transferring onto a transfer material on a transfer body, a transfer material detection means for detecting the presence or absence of a transfer material on a transfer material holding and conveying member; a transfer voltage application means;
The apparatus includes a control means for causing the transfer voltage applying means to start applying a voltage to the transfer material in response to a detection signal from the transfer material detection means.

Furthermore, by providing a control means for applying a voltage of the transfer voltage applying means to the transfer material according to the length of the transfer material in accordance with a detection signal from the transfer material detection means, the transfer material can be transferred in accordance with the size of the transfer material. A voltage can be applied. Then, the holding state of the transfer material is detected by the transfer material detection signal from the transfer material detection means, and based on the result, the separation means is activated to separate the transfer material that has completed the transfer process from the transfer material holding and conveying body. This prevents wasted operating time of the device. Below, in order to facilitate understanding of the present invention,
A specific example will be explained with reference to the drawings.

FIG. 1 illustrates an embodiment of a transfer type copying apparatus.

The original on the document platen glass 1 includes an illumination system (an iodine lamp 3 and a reflective shade 2) that is integrated with the first scanning mirror 4.
), and the reflected light is transmitted to the first scanning mirror 4 and the second scanning mirror 4.
It is scanned by a scanning mirror 5.

The first and second scanning mirrors move at a speed ratio of 1:1/2 to keep the optical length of the first half of the lens 6 constant. The above reflected light image passes through a lens 6 and reaches a color separation filter 7, which separates the light image into three colors (R (Red), G
(Green), B (Blue)) Filter 7
A, 7b, 7c, and the color-separated optical image forms an image on the photosensitive drum 14 via a fixed third mirror 8 and a fixed fourth mirror 9, and further through a dust-proof sealing glass 10.

The photosensitive drum 14 is rotatably supported on a shaft 53, rotates in the direction of the arrow with the printing operation, is positively charged, for example, by the primary charger 13, and then receives the color-separated light. While the image is irradiated, static electricity is removed by the AC static eliminator 11, and the entire surface is uniformly irradiated by the full-surface exposure lamp 54 to obtain a high-contrast electrostatic latent image. Photosensitive drum 14
The upper electrostatic latent image is then visualized by a developing device 15.

This developing device 15 includes C (cyan), M (magenta),
It is composed of four developing units 15a, 15b, 15c, and 15d for Y (yellow) and B&W (black). Each developing device includes a magnet 152, developer stirring screws 153, 154, and a waste carrier conveying screw 155 inside a non-magnetic sleeve 151. The developer replenished from Hopper 1 is Screw 15.
4 to one end and pushed up through the first openings of the upper and lower supporting plates 156, and after being uniformly stirred by 153, it is supplied to the surface of the sleeve 15 for development. On the other hand, a suction duct 16 is provided before and after each developing device, and the duct is further connected to a suction prower 21 via a dust collection filter 19 in a dust collection filter box 20.゛゛1゛1゜゛゛After development, the toner image on the photosensitive drum is charged with an arbitrary polarity by a post charger 22, and then reaches a transfer section.

The transfer material P is stored in a force set 40 that is detachably attached to the main body, and the force set 40 is attached to a shaft 4 fixed to an outer box 406.
03, a spring 407 that always biases the intermediate plate upward, a size switching plate 401 for the transfer material P, and a separation claw 408. This device has a similar force setting. It has two levels and stores paper of different sizes.

When you select either the upper or lower force set using the selection button in the operation section located on the top of the main unit, the pick up roll 3
Simultaneously with the operation of 6, the first timing roll 35 stops,
At this point, the transfer material P sent out from the force set forms a loop and stops instantaneously, and then reaches the second timing roll 31 via the guide 41 and the feed rolls 32 and 33. The second timing roll 31 stops a little before the transfer material reaches the transfer material P, so the transfer material P hits the second timing roll 31 to form a loop and then stops. After that, the second timing roll 3 is moved in synchronization with the toner image on the photosensitive drum.
Activate 1. The transfer material P contacts the transfer roll 24 via the guide 46, and is then subjected to a corona discharge from the back surface of the transfer material P with the same polarity as the post-charging polarity by the electrostatic attraction charger 23. electrostatically adheres to the surface.

The transfer roll 24 has a conductive rubber 243 wrapped around the outer periphery of an elastic roll 241 and is grounded.

The transfer material P electrostatically attracted to the transfer roll 24 is brought into pressure contact with the toner image on the photosensitive drum in synchronization with the toner image to transfer the toner image, and a yellow toner image is formed on the transfer material.
Similar steps are carried out using other red and green filters to sequentially expose and develop, and the transfer of cyan and magenta toner images is repeated. The transfer material P on the transfer roll repeats transfer three times in total while being electrostatically attracted. Also color separation filter 7
is changed to the next filter 1 during the reversal process of the optical system, and a 1:1 correspondence is set between filter 1 and its corresponding developing device by the programming device. As mentioned above, R, . G. Color separation exposure using each filter in B, C,
．． M. After development with the Y toner and three times of overlapping transfer, the program device operates the separation claw 25, and the electrostatically attracted transfer material P is peeled off from the transfer roll 24.
The image is conveyed to a fixing device 48 via a conveyor belt 47.

The fixing device 48 includes heaters 484, 48 . Further, an elastic roll 482 is installed between the two and brought into pressure contact with 481 and 482.

The fixing device having such a structure heats and melts the powder image on the transfer material P and fixes it. Further, the static electricity on the transfer material is removed by the static eliminator 49, and the transfer material is discharged onto a tray. After the transfer material P is peeled off, the transfer roll cleaning device 30 is activated by a command from the program device to clean the transfer roll, and the toner removed by the blade cleaner is conveyed to one side by the lower screw 29. and collected in the toner tray.

Further, after transferring the toner images of each color, the photosensitive drum 14
A cleaning device consisting of an elastic blade cleans the surface before the next cycle.

FIG. 2 explains the transfer unit mechanism. When the leading edge of the transfer material passes through the guide 46 or once wraps around the transfer roll 24 and reaches a position where it is irradiated by the lamp L3 again, a light receiving element CdS3 such as CdS catches the reflected light. The lamp L3 is turned on at a timing synchronized with the toner image on the photosensitive drum 14. In this embodiment, since the photosensitive drum 14 and the transfer roll 24 having an integer ratio are mechanically engaged with their respective gears, the micro switch MS-b (FIG. 3a) is activated by the cam 319 on the transfer roll. By setting the power to 0N and lighting the lamp L3, timing synchronized with the toner image can be obtained. At this time, if the transfer material does not come, CdS3
Since there is no light from the lamp L3, switch SW7 for the transfer bias applied to the transfer roll, or switch SW7' for charging before transfer, is not turned on, and when the transfer material arrives, the switch SW7 is not turned on. It is configured to look like a person.
Therefore, when performing three transfers, the same operation is performed three times, and an example of the circuit configuration is shown in FIG. That is, lamp L3
The change in current of the light receiving element CdS3 that receives the reflected light is amplified by the operational amplifier OPA, transistors T and l are turned on, and relay R is excited. With this configuration, the transfer material is excited during the transfer operation. On the other hand, if the switch contact of this excited relay R is used as the direct transfer roll or the pre-transfer charging bias power switch SW7 or SW77, it will operate faster by 12 lengths as shown in the second figure. Synchronize with a corresponding delay using a CR timer, etc.

An example of the circuit and signal waveforms are shown in FIG. 2C and d. That is, a signal slightly delayed by the capacitor C with respect to the detection signal A is output at the N point. By inputting this signal into C (TA75O4), a signal delayed by the required delay time Δt is obtained at point B. This signal can be used to activate relay R. In the above example, the transfer material itself is used as the switch signal source, but in response to the detection signal of the transfer material, another program detects whether the transfer material is A4 size or B4 size, for example. Depending on the size detection signal, a transfer material such as A4 or B4 is transferred to the transfer roll 24 and the photosensitive drum 14.
It may be configured such that SW7 or SW7' is held in the ON state while passing between the two.

In addition, if the color of the transfer roll is similar in brightness to the transfer material,
Since it is difficult to detect the light receiving element, if the transfer roll is made of metal, it should be plated with black or other color, or if it is made of rubber, black conductive rubber can be used. The resistance change becomes noticeable.

In addition, in the second illustrated example, if this type of machine is working normally, the lamp L3 should be switched off at the point when the leading edge of the transfer material almost passes through the working part of the transfer material detection device. However, if the lamp is always on, the transfer roll can be made ready for transfer by the length of the transfer material, regardless of the slow speed at which the transfer material is fed and transferred.

On the other hand, if the transfer material is fed out of position with respect to its normal position or if a shift occurs during the transfer operation, the separation claw 25 may be operated in response to the detection signal to transport the transfer material out of the machine. .

The present invention is configured to detect the presence or absence of the transfer material P and the size of the transfer material as described above, and then control the operation of the transfer means such as the transfer bias or pre-transfer charging.

Therefore, toner is less likely to adhere to areas on the transfer roll where there is no transfer material, and in the case of a transfer method that applies a high potential negative, the photosensitive plate can be transferred without using an insulator (transfer material). Since there is no direct contact with the high potential transfer roll, the photoreceptor will not be damaged. In addition, the transfer material can be detected over a length that almost matches the length of the transfer material and at a time corresponding to the image on the photosensitive drum, and the presence or absence and position of the transfer material can be detected immediately before or after transfer. Transfer material that is no longer useful as a copy can be ejected immediately.This is done each time a transfer is made, minimizing wasted operating time.Especially in color copying, the transfer roll is transferred three times. Therefore, it is possible to prevent a half-finished copy in which it takes a long time to complete the copy and the entire original is not copied.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the copying apparatus according to the present invention, FIG. 2 is a partial sectional view of the transfer unit mechanism, and FIGS.
Figure d is an example of a control circuit. In the figure, 1 is a document table glass, 14 is a photosensitive drum, 24 is a transfer roll, and L3 and CdS3 are means for detecting the transfer material P.

Claims (1)

[Scope of Claims] 1. An electrostatic latent image corresponding to each color component is formed on a photoconductor, each latent image is developed with a corresponding developer of each color, and each color developed image is transferred onto a transfer material holding and conveying member. A multi-transfer device that obtains a multicolor image by repeating the process of transferring onto a transfer material includes: a transfer material detection means for detecting the presence or absence of a transfer material on a transfer material holding and conveying body; a transfer voltage application means; and a transfer material detection means. 1. A multiple transfer device comprising: control means for causing a transfer voltage application means to start applying a voltage to a transfer material according to a detection signal. 2. Form an electrostatic latent image according to each color component on the photoconductor, develop each latent image with a corresponding developer of each color, and transfer the developed image of each color to the transfer material on the transfer material holding and conveying member. A multi-transfer device that obtains a multicolor image by repeating processes includes a transfer material detection means for detecting the presence or absence of a transfer material on a transfer material holding and conveying body, a transfer voltage application means, and a detection signal applied to the transfer material by the transfer material detection means. 1. A multiple transfer device comprising: control means for applying a voltage of a transfer voltage applying means in accordance with the length of a transfer material. 3. Form an electrostatic latent image according to each color component on the photoconductor, develop each latent image with a corresponding developer of each color, and transfer the developed image of each color to the transfer material on the transfer material holding and conveying member. A multi-transfer device that obtains multicolor development by repeating processes includes a transfer material detection means for detecting the presence or absence of a transfer material on a transfer material holding and conveying body, a transfer voltage application means, and a detection signal applied to the transfer material by the transfer material detection means. a means for controlling the voltage application operation of the transfer voltage applying means according to the transfer process, and a separating means for separating the transfer material after the transfer process from the transfer material holding and conveying body, and the transfer material is detected by the transfer material detection means. A multiple transfer device comprising: detecting the holding state of the transfer material based on a signal; and operating the separation means based on the detection result to separate the transfer material from the transfer material holding and conveying body.