JPH043183A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain excellent image quality, always specified and good transfer efficiency and separability by using an LED array in a pre-transfer exposing part and controlling the voltage or current of the LED array by a sensor which is provided in the image forming device and measures temp. or humidity. CONSTITUTION:The LED array is used for the pre-transfer exposing part of the image forming device provided with the pre-transfer exposing part between a developing device and a transfer device in the peripheral edge part of a turning image carrying member and the voltage or current of the LED array is controlled by the sensor which is provided in the image forming device and measures the temp. or humidity. Namely, this image forming device has a pre-transfer exposing part lamp 13 which is the pre- transfer exposing part consisting of the LED array, a transfer material supplying device 50, paper feed rollers 51, a transfer device 14 which is an electrifier for transfer, a separating device 15 which is a destaticizer for sepn., and the sensor 21 which is provided in the peripheral edge part of a photosensitive drum 10 and obtains the information on the temp. or humidity in the device. The excellent image quality is obtd. by the simple constitution in this way without being affected by environmental conditions and the transfer efficiency of the toner images to a transfer material and the separability of the transfer material from the image carrying member are always well maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus such as an electrophotographic copying machine, in which a toner image on an image carrier is transferred to a transfer material, and the transfer efficiency is improved.
The present invention also relates to an image forming apparatus that improves the separation property when separating the transfer material from the image carrier so that a good image can be obtained.

[Conventional technology]

Generally, in an electrophotographic image forming apparatus, a sheet-like transfer material is attached to a toner image electrostatically adhered to an image carrier having a photoreceptor layer, and a transfer device is used to transfer the transfer material from behind the transfer material. A separator l which attaches the toner image to the transfer material by performing transfer charging with a polarity opposite to that of the toner image, and which performs charging with a polarity opposite to that of the transfer device or an alternating current bias.
This is how the charge remaining on the transfer material is removed and the transfer material is separated from the image carrier.

In order to improve the transfer efficiency and separability during the above-mentioned transfer and separation, a pre-transfer exposure section is provided between the developing device and the transfer section of the secondary image carrier periphery IIts, and a cold cathode discharge tube or the like is used for pre-transfer exposure. A lamp (hereinafter referred to as PTL) is installed to irradiate an image bearing member on which a toner image has been formed to weakly eliminate static electricity by photoconduction.

[Problem to be solved by the invention]

The charge removal by pre-transfer exposure using PTL is performed by irradiating light onto the image carrier to which the toner image is attached, but when observed in detail, the gaps between the toner particles attached to the image carrier This is done by inputting light from the PTL.

However, if this PTL is made to turn on all the time,
The irradiated light enters the photoreceptor layer of the image carrier, scatters and reflects within the photoreceptor layer, circulates around the layer, and removes the charge, which disturbs the charged state and causes the toner particles that were forming the toner image to become stuck on the image carrier. It sometimes moved slightly over the body, causing image disturbances and lowering the image quality.

In addition, when a switch is provided on the PTL and the separability is deemed to be good, the PTL switch is manually turned off. This has caused problems such as paper jams and other problems resulting in poor paper passing.

Furthermore, the transfer efficiency of the toner image onto the transfer material and the separability of the transfer material from the image carrier after the toner image transfer will be affected by changes in environmental conditions such as the temperature inside the device during image formation and the temperature of the transfer material. There is a property that the transfer efficiency and separability in charging and neutralization deteriorate due to changes in the resistance value. A technique for suppressing changes in transfer efficiency and separability due to changes in environmental conditions is disclosed, for example, in Japanese Patent Application Laid-Open No. 56-69653, but nothing is described regarding the use of PTL.

The present invention solves the above problems, has a simple structure, has excellent image quality, and has consistently good transfer efficiency and separation.
Therefore, it is an object of the present invention to provide an image forming apparatus that has excellent paper passing properties for transfer materials.

[Means to solve the problem]

The object is to provide an image forming apparatus in which a pre-transfer exposure section is provided between a developing device and a transfer section at the peripheral edge of a rotating image carrier, in which an LED array is used in the pre-transfer exposure section; This is achieved by an image forming apparatus characterized in that the voltage or current of the LED array is controlled by a temperature or a sensor for measuring temperature provided within the image forming apparatus.

〔Example〕

FIG. 1 is a configuration diagram showing an embodiment of an image forming apparatus of the present invention. In the figure, IO is a photosensitive drum which is a drum-shaped image carrier, 11 is a charger that charges the circumferential surface of the photosensitive drum 10, 30 is an exposure device, 12 is an image exposure section, 40 is a developer, and 13 is an LED. A pre-transfer exposure lamp (PTL) which is a pre-transfer exposure unit consisting of an array, 50 a transfer material supply device, 51 a paper feed roller, P a recording paper which is a transfer material, 14
15 is a separator that is a static eliminator for separation; 21 is a sensor provided at the peripheral edge of the photosensitive drum 10 for obtaining information about the temperature inside the device (inside the machine); , 60 is a fixing device, 70 is a cleaning device, 52
is a conveyor belt which is a means for conveying the recording paper P.

In the conventional PTL using a cold cathode discharge tube, it is difficult to stably increase or decrease the amount of emitted light by adjusting the applied voltage or current, but the PTL of this embodiment has the following advantages: Since an LED array was used, it became possible to freely and stably adjust the amount of light by changing the applied voltage and current.

To explain the operation of the image forming apparatus, the peripheral surface of the photoreceptor drum 10 is uniformly charged by the charger 11, and then the peripheral surface of the photoreceptor drum 10 is exposed to light in the image exposure section 12 by the exposure device 30 to electrostatically charge the peripheral surface of the photoreceptor drum 10. form a latent image.

Thereafter, the latent image is developed and visualized by the developing device 40 to become a toner image. This toner image is subjected to pre-transfer exposure by the PTL 13 to which a predetermined voltage is applied under the control of the control unit 20 based on information from the sensor 21, and then the paper is fed from the paper feeder 50 at the same timing. The image is transferred onto the recording paper P fed by the roller 51. This transfer is performed by charging the recording paper P with a polarity opposite to that of the toner by a transfer device 14 from behind. A high alternating current voltage is applied by the post-transfer separator 15 to eliminate static electricity, and the recording paper P is separated from the photoreceptor drum IO. The separated recording paper P is transferred to the conveyor belt 521: therefore, the fixing device 60I
; the toner image is fixed on the recording paper and discharged outside the apparatus.

On the other hand, the photosensitive drum 10 to which the toner image has been transferred is cleaned of residual toner on the circumferential surface by a cleaning device 70, and is ready for the next copy.

When controlling the voltage applied to PTL 13, for example, when sensor 2 = temperature sensor is used, the relationship shown in Table 1 below is established, and transfer efficiency, separation performance, and image quality are all good. Good results were obtained.

Table 1, FIG. 2 shows an example of the 70-chart for the above control. If the temperature inside the machine exceeds 30°C, the applied voltage of PTL 13 is set to 24V in this embodiment, but it is also possible to detect a temperature of 40°C or higher, and an alarm is issued at this point. The device may be configured to notify the operator of the abnormality or to issue an alarm and stop the operation of the device at the same time.

In addition, when a temperature sensor is used as the sensor 21, PTI
, 13, the relationship between the applied voltage and the relative temperature inside the machine is as follows:
Good results were obtained as shown in the table.

In the above example, the applied voltage of the PTL 13 was changed according to the environmental conditions to increase or decrease the amount of light emitted by the PTL 13, but the applied voltage was held constant and the energizing current was controlled. Of course, it is also possible to increase or decrease the amount of light emitted from the PTL 13.

〔Effect of the invention〕

According to the present invention, with the configuration and control as described above,
The pre-transfer exposure amount is automatically adjusted according to environmental conditions. Therefore, the image quality is excellent without being affected by environmental conditions with a simple configuration, the transfer efficiency of the toner image to the transfer material and the separation of the transfer material from the image carrier are always maintained well, and the paper passing property is improved. It has now become possible to provide a significantly superior image forming apparatus.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the image forming apparatus of the present invention, and FIG. 2 is a flowchart showing an example of applied voltage control of the PTL shown in FIG. IO...Photosensitive drum 11...Charger 12...
・Image exposure section 13...Pre-transfer exposure section lamp (PTL) 14...Transfer device 15...Separator 20...Control section 21...Sensor 40...Developer P...Recording Paper figure 2

Claims (1)

[Claims] In an image forming apparatus in which a pre-transfer exposure section is provided between a developing device and a transfer section at the peripheral edge of a rotating image carrier, an LED array is used in the pre-transfer exposure section, and an LED array is provided in the image forming apparatus. An image forming apparatus characterized in that the voltage or current of the LED array is controlled by a temperature or a sensor that measures temperature.