JPS61267072A - Separation detector - Google Patents

Abstract

PURPOSE:To detect a defect in separation and stop the conveyance of a transfer material and the operation of respective members before a jam occurs by detecting the transfer material by an actuator an almost similar time after the transfer paper leaves a supply position whichever course the transfer material passes through. CONSTITUTION:A toner image which can be transferred is formed on the surface photoconductive layer of an image carrier (photosensitive body) 1 which rotates as shown by an arrow A by an image forming members such as primary electrostatic charger, a light image forming means, a development path. Further, the toner image is transferred through the operation of a transfer charger 3 to the transfer material which contacts or comes close to the toner image on the photosensitive body 1 through a one-way conveyance path 2. The transfer material which is charged at a transfer position and carries the toner image is discharged through the operation of a separating charger 4 to leave the surface of the photosensitive body 1 and advances as shown by an arrow lto reaches the actuator 6 of a detecting means.

Description

[Detailed Description of the Invention] (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrophotographic copying machine or a printer, and particularly to a separation detection device thereof. It is.

(Prior art and problems to be solved) A sheet-like transfer material, mainly made of ordinary paper, is brought close to or in contact with a transferable toner image formed on the surface of an endlessly running image carrier. Image forming apparatuses are conventionally known in which the steps of separating the transfer material from the image carrier and removing residual toner remaining on the surface of the image carrier with a cleaner after transferring the toner to the transfer material are conventionally known. .

In such an image forming apparatus, since the transfer material that comes close to or comes into contact with the image carrier for transfer tends to be attracted to the image carrier, a charger for separation is provided at the separation site. Separation means that neutralize the charge on the transfer material during transfer and separate the transfer material are widely used.

Although such electrostatic separation means is superior in terms of damage to the photoconductive layer on the surface of the image carrier and deterioration of the image, compared to separation means using mechanical means such as one separation claw and one separation belt, On the other hand, because it uses electrostatic phenomenon,
It is easily influenced by the environment, especially humidity, and it has not always been easy to maintain a stable separation effect.

For this purpose, a separation detection means is provided at the upstream position of the cleaner (and after separation), so that the actuator operates when the separation action is performed, and when the actuator does not operate, it is determined that the separation is defective. Some methods have already been proposed that stop the drive and conveyance of the transfer material.

It goes without saying that such a detection means must be capable of detecting and stopping the occurrence of separation failure before the transfer material reaches the cleaning device.

However, as a practical matter, the path of the transfer material is almost constant when separation is performed in a predetermined manner, but the path of the transfer material is not constant when separation occurs, so it is difficult to detect the movement of the actuator. Because it is necessary to take a long time to transfer the transfer material, it is difficult to stop the conveyance of the transfer material before the transfer material enters the cleaning device. Furthermore, by the time the course of the transfer material becomes approximately constant, the point is far from the separation point, that is, close to the cleaning device, so it is ineffective to dispose an actuator at this location.

The present invention has been completed to deal with such a situation, and in the above-mentioned image forming apparatus, no matter what path the transfer material travels through, it is generally the same from the supply position. By configuring the actuator to detect the transfer material after a period of time has elapsed, it is possible to ensure that the conveyance of the transfer material and the operation of each member are reliably stopped after a separation failure is detected, before a jam occurs. The object of the present invention is to provide such a separation detection device.

(2) Structure of the invention (technical means for solving the problem, its effect) In order to achieve the above object, in the present invention, a detection means is provided when the transfer material advances along the regular conveyance path after the separation site. The structure is such that even if a separation failure occurs, this failure can be detected in the same time as it takes for the actuator to reach the actuator.

With this configuration, even if a separation failure occurs, troubles such as the transfer material rushing into the cleaning device and causing a jam can be prevented, and the transfer material can be reliably transported before that happens. It is possible to stop the operation of each member as necessary.

(Description of Embodiments) FIG. 1 is a schematic side view showing the main parts of an embodiment in which the present invention is applied to an image forming apparatus equipped with an image carrier formed in the shape of a rotating cylinder.

A transferable toner image is formed on the photoconductive layer on the surface of an image carrier (photoreceptor) 1 rotating in the direction of arrow A by an image forming member (not shown) such as a negative charger, an optical image forming means, a developing device, etc. On the other hand, the toner image is transferred through the conveyance path 2 to a transfer material (not shown) that comes into contact with or near the toner image on the photoreceptor 1 by the action of the transfer charger 3. shall be.

The transfer material carrying the toner image is then neutralized by the action of the separation charger 4 to neutralize the electric charge obtained at the transfer site, moves away from the surface of the photoreceptor 1, moves along the arrow 2 shown in the figure, and reaches the actuator of the detection means. Reach position 6.

If the code 2 represents the distance from the point P where the transfer material is supplied to the photoconductor to the actuator 6, then the point P
The distance between the cleaning blade 7at and the cleaning blade 7at disposed on the cleaning device 7 is also made small.

In such a configuration, when the angle θ between the actuator 6 and the vertical direction is changed and the time required to detect the presence of the transfer material is measured, the results are approximately as shown in FIG. 2.

That is, in the figure, line a shows the change in time with respect to θ when the transfer material passes through the regular conveyance path, that is, when the separation is performed correctly, and as can be seen from the figure, it is almost constant. becomes.

On the other hand, the separation did not go well and the transfer material remained on the photoreceptor 1 for some time.
When the transfer material travels along the curved surface of and then is separated, as θ becomes larger, the time required for the actuator to detect the presence of the transfer material becomes shorter, and the two coincide when the angle θG is reached. In other words, regardless of the traveling path of the transfer material when θ0, the presence of the transfer material will be detected after a certain period of time.

Angle θ. It is inevitable that the value will vary slightly depending on the type of transfer material, the function of each charger, the environment, etc., but by assuming the image forming devices that are widely used and their operating conditions, it is possible to determine the effective Can be set to size.

With this configuration, the position of the transfer material can always be determined in the shortest possible time, and the driving of the photoreceptor and the conveyance of the transfer material can be stopped.

FIG. 3 shows another embodiment of the present invention, and the basic configuration of the image forming apparatus itself is the same as that in FIG.
Corresponding parts are denoted by the same reference numerals, and a description thereof will be omitted.

In this device, a photointerrupter consisting of a light emitting element 8a and a light receiving element 8b is used, and the traveling direction of the luminous flux is set at θ with respect to the perpendicular direction. Arrange it so that it forms.

With this configuration, there is no resistance to the transfer material, so smooth conveyance can be maintained.

(3) Effects of the Invention Since the detection device according to the present invention has the above-mentioned structural functions, the presence of the transfer material can be detected in the shortest possible time after the toner image is received and the transfer material is separated from the image carrier. After detection, conveyance of the transfer material and driving of the photoreceptor and other components can be stopped with sufficient time without jamming of the transfer material, which greatly contributes to improving work efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the main parts of an embodiment of an image forming apparatus showing the configuration of the present invention. FIG. 2 is a graph showing the action of the detection member (actuator). FIG. FIG. 7 is a schematic side view of main parts of an image forming apparatus showing another embodiment. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Conveyance path, 3... Transfer charger, 4... Separation charger, 6... Actuator, 8a
... Light emitting element, 8b... Light receiving element

Claims (1)

[Scope of Claims] After a synchronously traveling sheet-like transfer material is brought into contact with or close to the toner image on the surface of a traveling image carrier and the toner image is transferred to the transfer material, the transfer material is transferred to the image carrier. In an image forming apparatus that separates the transfer material from the image carrier and transports it, the transfer material is separated from the image carrier at a position after the transfer material is separated from the image carrier and is transported, regardless of the traveling path of the transfer material after the transfer material is supplied to the image carrier for transfer. A separation detection device that detects the presence of a transfer material after a predetermined time from the time of supply.