JPS58127948A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To obtain stable picture images at any temp. by detecting the temp. of a photoreceptor or near the same, and controlling developing bias according to the detection signal thereof. CONSTITUTION:A potential sensor 45 is provided in the position in a post stage of an electrostatic charger 42 near a photoreceptor 41a, and the potential of the photoreceptor after electrostatic charging is detected with said sensor. According to the detected potential, the voltage of the charger 42 is controlled to control the charging potential on the photoreceptor 41a so as to make the same constant. A temp. sensor 46 is provided in a position near the photoreceptor 41a, and measures the temp. of the photoreceptor 41a. The sensor 46 detects the temp. of the photoreceptor which is so controlled as to provide linear or stepwise developing bias. The charging potential is controlled to be constant and the developing bias is controlled according to temp. in the above-mentioned way, whereby the process control is accomplished surely even with an electrophotographic receptor having temp. dependency and the image quality is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic recording device having a temperature-dependent photoconductor, and more specifically, the present invention relates to an electrostatic recording device having a temperature-dependent photoconductor, and more specifically, the above-described photoconductor controls charging and exposure even when there is a temperature change, thereby stably achieving good performance. The present invention relates to an improvement in an electrostatic recording device capable of obtaining a reproduced image.

In general, when a temperature-dependent photoreceptor is used in an electrostatic recording device, it is known that the characteristics of the photoreceptor change due to changes in temperature within the electrostatic recording device, which may affect multiple images.

Furthermore, in an electrostatic recording apparatus using a temperature-dependent photoreceptor, methods for controlling various conditions such as charging and development in order to obtain stable copied images are known.

(1) Methods for controlling charging include (1-1) A method of controlling the charging potential to a constant level by detecting the charging potential of the photoreceptor or the dark area potential of the photoreceptor.

(1-2) A method of controlling the charging potential to be constant by detecting the temperature of the photoreceptor.

(2) Methods for controlling development (2-1)
A method of controlling the developing bias value by detecting the level of bright and dark areas on the photoreceptor.

(2-2) A method of detecting the temperature of the photoreceptor and controlling the development resistance value.

There is. However, with the above conventional techniques, it is impossible to obtain a satisfactory copy image.0(1-1)(1-2
), since the sensitivity of the photoreceptor changes depending on the temperature, the exposure conditions and developing bias are the same, resulting in a decrease in image density at high temperatures and the sound of fogging at low temperatures.

(2-1) In (2-2), since the charging potential of the photoreceptor when charged under the same conditions varies depending on the temperature,
Even if the developing bias conditions are controlled, the image density decreases at high temperatures, and fogging occurs at low temperatures.

In the case of a temperature-dependent photoreceptor, as shown in the relationship diagram between charging potential and photoreceptor temperature in FIG. 1, the charging potential decreases as the photoreceptor temperature increases under the same charging conditions. Furthermore, as shown in the relationship between the photoreceptor temperature and the amount of halved charging light (the amount of irradiated light required to reduce the charged potential of the photoreceptor by half) in Figure 2, the sensitivity improves as the photoreceptor temperature rises. .

The present invention is an electrostatic recording device that uses a temperature-dependent photoreceptor, and controls charging and developing bias to obtain a stable image at any temperature. In an electrostatic recording device that detects the body surface potential and controls the charging means based on the detection signal to keep the charging potential almost constant, the temperature of the photoreceptor or its vicinity is detected and the developing bias is adjusted based on the detection signal. The present invention provides an electrostatic recording device fi'fi which is characterized in that it controls.

That is, the charged potential of the photoreceptor is controlled by detecting the potential after the photoreceptor is charged, or the dark area potential of the photoreceptor is formed by 2-standard exposure, and the charged potential of the photoreceptor is kept almost constant at any temperature by controlling by detecting the potential. By detecting the temperature of the photoreceptor and controlling the developing bias amount to vary according to the temperature, a stable image can be obtained at any temperature.

No. 31A shows the relationship between the photoreceptor temperature and potential according to the present invention. No. 31 is the charging potential that is controlled to be kept almost constant regardless of the photoreceptor temperature, and the bright and dark areas of the image at this time are In terms of potential, 32 indicates the dark part of the image, and 33 indicates the bright part (background) potential. 34 is a developing bias which detects the temperature of the photoreceptor and thereby changes and controls the developing bias depending on the temperature. Although the relationship between the photoreceptor temperature and the developing bias shown in Figure 3 is linear, it is also possible to perform stepwise control as a stepwise curve to the extent that no difference is recognized in the copied image. be.

FIG. 4 is a schematic diagram of an embodiment of the present invention, in which the potential of the photoreceptor after being charged is detected to control the amount of charge to a constant level, and the temperature of the photoreceptor is measured to control the developing bias. This is seven examples. In the figure, reference numeral 41 denotes a photoreceptor drum, and on its circumferential surface is a temperature-dependent photoreceptor 41 having charging characteristics as shown in FIG. 1 and sensitivity characteristics as shown in FIG.
A is stretched and rotates clockwise. 42 is a charger that charges the photoreceptor 41&, and 43 is an image exposure section.

A real image of the document is projected by the image exposure section 43 onto the photoreceptor 41a, which is uniformly charged by the charger 42, to form a latent image. 44- is a photoreceptor 51a that performs development in a developing section.
Toner is applied to the upper latent image to form a toner image. During development, the amount of toner adhering to the latent image portion changes according to changes in the developing bias, and development is performed under different conditions.

In the general electrostatic recording device described above, the potential sensor 45 is provided in the vicinity of the photoreceptor 411L and at a position corresponding to the post-processing of the charger 42, and detects the photoreceptor potential after charging.
The voltage of the charger 42 is controlled according to the photoreceptor potential after charging, so that the charging potential on the photoreceptor 41a is constant.

Reference numeral 46 denotes a temperature sensor, which is provided at a position close to the photoreceptor 41m and measures the temperature of the photoreceptor 41. The temperature sensor 46 is a contact type or non-contact type thermocouple, thermistor, etc., and detects the temperature of the photoreceptor, and the temperature sensor 46 detects the temperature of the photoreceptor.
Control is performed so that the developing bias is linear or stepwise as shown in 4.

FIG. 5 shows potential detection by potential sensor 45 and temperature sensor 4.
6 is a timing chart in which charging and developing bias are applied in response to temperature detection by No. 6; FIG. Here, the control of the charging means or the control of the developing bias is controlled so as to be kept constant at least during the charging step for substantially recording both images or during the developing step.

Note that in this embodiment, the charger was controlled by detecting the photoreceptor potential, but as another method of potential detection, it is also possible to detect the potential of the bright and dark areas of the image and control the charger based on this. There it is. Regarding this, JP-A-55-1171
No. 64, JP-A-53-98834, JP-A-Sho. 5
Detailed proposals have been made in Publication No. 4-17847 and the like.

Although one embodiment has been described above, the present invention enables process control even in temperature-dependent electrophotographic photoreceptors by controlling the charging potential to a constant level and controlling the developing bias according to the temperature. This can ensure that the image quality is stabilized.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the photoreceptor temperature and charging potential, and FIG. 2 shows the relationship between the photoreceptor temperature and the half-reduced amount of charging light. FIG. 3 shows the relationship between the charging potential and the developing bias controlled by the present invention, FIG. 4 shows a schematic configuration diagram of an embodiment of the present invention, and FIG. 5 shows a timing chart of this embodiment. , 51... Photoconductor drum 51g... Photoconductor 52
...Charger 53...Image exposure section 54...
・Developing section 55... Potential sensor 56... Temperature sensor agent Yoshimi Kuwahara

Claims (3)

[Claims] (1) In an electrostatic recording device that detects the surface potential of the photoreceptor before or after exposure and controls the charging means based on the detection signal to keep the charging potential approximately constant, the temperature of the photoreceptor or its vicinity is detected. An electrostatic recording device characterized in that the developing bias is controlled based on the detected signal. (2) The electrostatic recording apparatus according to claim 1, wherein control of the charging means is maintained constant at least during the charging process for recording one substantial image. (3) Electrostatic recording according to claim 1 or 2, characterized in that the development bias is kept constant at least during the development process for recording a substantial image. Device.