JPS58125062A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To form a proper image, by detecting the temperature of or the vicinity of the surface of a photoconductive photoreceptor and controlling a charging means on the basis of this detection temperature signal to change the surface potential before exposure of said photoreceptor in accordance with the detected temperature. CONSTITUTION:An electrostatic recorder consists of a photoreceptor 1, a temperature sensor 2, a temperature detecting circuit 21, a corona charger 3, etc. The temperature of or the vicinity of the surface of the photoreceptor 1 is detected, and the charging means is controlled on the basis of the detection temperature signal to change the surface potential before exposure of the photoreceptor 1 in accordance with the detected temperature. By this method, the deficiency of the image density at a high temperature and the photographic fog at a low temperature are prevented to obtain a proper image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a photosensitive material using a photoconductive photoreceptor. The present invention relates to charging control of the photoconductive YB body (hereinafter abbreviated as photoconductor) in a recording device.

In general, when a photoreceptor used in an electrostatic recording device such as an electrophotographic copying machine or a laser printer is charged under constant charging conditions, the vertical axis shows the surface potential of the photoreceptor, as shown by curve V in Figure 1. As shown in the graph of Fig. 1, in which the photoreceptor temperature is plotted on the horizontal axis, the surface potential of the photoreceptor decreases as the temperature rises, and the image density of the film decreases at high temperatures. However, it had the disadvantage of causing fogging due to vomiting.

Therefore, the temperature of the photoreceptor is detected in advance, and charging conditions sufficient to compensate for the temperature dependence are provided, so that the surface potential of the photoreceptor before exposure is made uniform over a predetermined temperature and thickness range, as shown in Ve in Fig. 1. A proposal was made, and its specific technical content was also published in JP-A-5
No. 6-43648, No. 55-121453 and No. 54
-73055.

However, the photoreceptor also has temperature dependence regarding its sensitivity, and when expressed with the cow dew reduction device on the vertical axis and the temperature on the horizontal axis as shown in Figure 2, the half-reduced muscle mass c decreases with temperature. . In other words, the sensitivity increases or decreases as the temperature increases,
Even if the surface potential of the photoreceptor before exposure is made to remain constant against temperature changes over a predetermined temperature range, the image density will decrease at high temperatures and peeling will occur at low temperatures. There is a possibility that this may occur. In order to avoid the above-mentioned disadvantages and form a proper image, it is necessary to perform temperature compensation for the same potential charge σ) as described above and to correct the exposed silver, which complicates the structure of the electrostatic recording apparatus.

In view of the above-mentioned circumstances, the present invention compensates for the temperature dependence of a photoreceptor by a simple means, thereby achieving uniform image quality with good reproducibility at least over the practical operating temperature range of an electrostatic recording device. The object of the present invention is to provide an electrostatic recording device that can create a copy image of.

The object of the present invention stated above is to provide a copying bag ff using a photoreceptor.
At step f, the temperature on or near the surface of the photoreceptor is detected, and the charging means is controlled based on the detected temperature signal [7, every time the surface potential of the yC body before exposure is changed according to the detected temperature. This can be accomplished by a characteristic electrostatic recording device. The specific implementation is to increase/decrease the charging potential as the detected temperature rises/falls, and also to control the image exposure to avoid the control due to temperature changes from temperature detection to charging and exposure. In order to control the charging potential based on the detected temperature near the immediately preceding photoreceptor surface solidified G (hereinafter referred to as the surface position), and to avoid the disadvantages of excessive control due to the sensitivity of the temperature sensor, etc. Selecting a representative temperature from the surface position of the photoconductor surface receiving image exposure C, setting a one-level charging potential based on the representative temperature, and charging the photoconductor surface portion while keeping it unchanged at the potential. is also a preferred embodiment.

Next, the present invention will be explained from the original document configuration. As already mentioned, the conventional method focuses on the temperature dependence of charging without considering the humidity dependence of the sensitivity of the photoreceptor, and performs temperature compensation over a predetermined temperature range to generate a predetermined band 1! It was to grant him a royal position.

As long as this method is used, as shown in Figure 3, the surface potential of the photoreceptor after exposure in both the bright and dark areas of the image decreases as the surface becomes hotter. There is a risk of fogging. In Fig. 3, the vertical axis is the potential, the horizontal axis is the temperature, and vc is the applied charging potential, V
D and VL are the dark potential and bright potential after exposure, respectively.

On the other hand, in the present invention, in order to compensate for the temperature dependence of the photoreceptor as a whole, the surface potential C of the photoreceptor after being charged and exposed (referred to as charge potential) is kept constant regardless of temperature changes. Instead, the charging means is controlled so as to change in response to temperature changes. This change in charge potential with respect to temperature is a change that increases as the temperature rises.

To explain this in detail using the example shown in Figure 4, as shown in Figure 4, in order to compensate for the temperature dependence of the sensitivity of the photoreceptor, the charging The dark area potential VD and bright area potential N after exposure are controlled by
/L are to be kept constant at least over the practical operating temperature range of the light body.

As is clear from FIG. 4, the charge level before exposure C1 of the photoreceptor to be applied is Jfl! It is necessary to control the temperature so that it increases as the temperature rises and decreases as the temperature falls.Temperature detection is performed by measuring the temperature of the surface of the sensing body using a contact type temperature sensor. It can be detected directly or near the surface of the photoreceptor using a non-contact temperature sensor.By inputting the detected temperature signal into a control device and selecting a method for controlling the charging means, various charging control systems can be used. can be assembled.

In addition, from the viewpoint of followability of charge control to detected temperature, two typical charge control systems and an intermediate system can be created.

One typical example is an analog control system that continuously detects the temperature of the surface potential of a photoreceptor in an analog manner, and charges the corresponding photoreceptor surface in an analog manner according to the detected temperature.

The other method is to sample the representative temperature of a predetermined part of the surface of the photoreceptor that is newly subjected to image exposure, such as the image leading edge of the image layer light, and charge a charge at one level corresponding to that temperature. A control system that uniformly applies a charge to the entire surface area newly subjected to image exposure, wherein the charge for one copy cycle is maintained at a constant value determined at the start of charging, and It is possible to detect the temperature at multiple points on the surface of the photoreceptor that receives image exposure, such as the leading edge, center, and edge of the image, and use the average temperature as a representative set temperature for the charging level, making it practical. It is highly effective.

In addition, in order to increase the practical effectiveness of temperature detection at the surface position of the photoreceptor, that is, to accurately and effectively compensate for the temperature dependence of the photoreceptor's chargeability and sensitivity, temperature detection, charging, and image exposure must be performed locally. Of course, the detected temperature information used for charging control and the charging state with respect to exposure should be matched to It has to be at least practically fresh.

Therefore, it is preferable that temperature detection, charging based on the detected temperature, and image exposure be performed in this order continuously at short intervals.

From a spatial perspective, it is preferable that the temperature sensor charging means and the image exposure means for carrying out the three steps are disposed close to each other in terms of the timing of the three steps described above.

Temperature sensors can be either contact or non-contact, such as thermocouples, thermistors, semiconductor temperature sensors, oscillator temperature sensors, thermal sensors, or photon sensors.

The number and position of the temperature sensors may be determined by taking into account any of the three control systems described above or the type of copying machine. When installing the temperature sensor on a long belt-shaped photoreceptor where the temperature sensor can be placed freely, the above-mentioned close placement must not be forgotten. Furthermore, the arrangement may be fixed or may be movable.

The charging control mechanism of the charging means that is controlled based on the temperature detected by the temperature sensor may be any mechanism that can generate the charging potential VC with temperature compensation as shown in Figure 4 of @11.
You may choose any of them. For example, (1) the electrician of the corona discharge wire that imparts charge to the surface of the photoreceptor by corona discharge may be controlled so that the charging potential Vc corresponds to the detected temperature. Further, when using a belt mechanism having a control grid such as a suflotron, the grid voltage may be adapted to the above-mentioned Vc. (2) A shield may be provided around the corona discharge wire, and the outflow amount of the corona ion flow may be controlled by a charging shield plate that controls the opening width of the shield to the photoreceptor surface.

Alternatively, (3) the distance between the corona discharge wire and the photoreceptor surface may be controlled, and the control may be based on the probability of corona ions reaching the photoreceptor surface or the charging life. Of course, these may be used in combination.

The control device that controls the charging means as described above based on the detected temperature signal from the temperature sensor can be easily configured by using a control circuit commonly used in control engineering.

As described above, by imparting a charging potential to the photoreceptor that compensates for both the charging characteristics of the photoreceptor and the temperature dependence of sensitivity, and performing the transfer process, it is possible to at least reach a temperature within the practical temperature range for copying. Based on automatic temperature detection, the operator does not have to worry about the temperature and can always create copy images with good reproducibility, uniform and even image quality simply by controlling the @electronic temperature. This is useful for a type of copying apparatus using an intermediate transfer member as shown in FIG. 5 and described later, in which the temperature of the sensitive C member tends to increase or the temperature change range becomes large.

Next, the present invention will be explained by examples. FIG. 5 is an explanatory diagram of a copying machine using an intermediate transfer body that employs the charging control system of the present invention, and FIG. 6 is a time chart of control when an automatic document feeder is attached to the copying machine. be.

In FIG. 5, 1 is a photoreceptor, 2 is a temperature sensor, and 21 is a temperature detection circuit. 3 is a corona discharger, and 31 is a high voltage power supply that supplies high FJE and current to the corona discharger. 4 is an image exposure device. The temperature sensor 2, corona discharger 3, and image exposure device 4 are provided adjacent to each other. 5
The G toner developing device 6 is an intermediate transfer means. In this transfer device, the toner image on the photoreceptor 1 is transferred to the rollers 6], 62.
, 63, and the transferred toner image is transferred to the intermediate transfer member M at the positions of the rollers 63, 64.
The image is transferred and fixed onto the transfer paper P.

Although not shown, a heat source is provided inside the roller 63.
The toner image on the intermediate transfer body M is melted at the transfer and fixing position,
It is heated to a temperature that allows it to be fixed.

In the case of a copying apparatus that employs such an image recording system, the photoreceptor 1 rotates while contacting the heated intermediate transfer member M, and in this case, as in the present invention, the temperature dependence of the charging characteristics of the photoreceptor is It is particularly effective to control charging by taking into account not only the sensitivity but also the temperature dependence of sensitivity.

Reference numeral 7 denotes a control device containing a control program, which detects the temperature of the photoreceptor at the leading edge of the image using a temperature sensor 2 in response to a copy start signal So, and inputs a detected temperature signal St transmitted via a temperature detection circuit 21. , the above-mentioned charging potential Vc and charging timing are determined for the detected temperature, and a control signal 8c is input to the high voltage power supply 31. Furthermore, image exposure is started at the timing when the charged area enters the image exposure area.

FIG. 6 shows temperature detection, charging, and temperature detection in the embodiment shown in FIG.
It shows the control timing of the control.

Temperature sensing is performed for a short time t at the beginning of the copying cycle.

Do it inside. Takame:, Den i! The lX31 is turned off during each copying cycle, but the voltage to the corona discharger 3 is set to a value corresponding to the detected temperature when it is turned on, and is maintained at that set voltage during one copying cycle.

[Brief explanation of drawings]

FIG. 1 is a graph showing the temperature dependence of the charging characteristics of the photoreceptor, and FIG. 2 is a graph showing the temperature dependence of the sensitivity of the photoreceptor. FIG. 3 shows the image surface potential when exposed with temperature compensation only for charging characteristics, and FIG. 4 shows the image surface potential when exposed with temperature compensation for both the charging characteristics of the photoreceptor and the temperature dependence of sensitivity. FIG. 5 is an explanatory diagram of one embodiment of the present invention, and FIG. 6 is a time chart of temperature detection, charging, and image exposure. Vc...charged potential, Vo...dark potential, VL...
・Bright area potential, 1... Photoreceptor, 2... Temperature sensor, 3... Corona discharger, 4... Image exposure device, 7
···Control device. Agent Kuwahara Kuwami 13- Kan 1 closed criticism ゛-51 degrees→ 5 drawings 4 figures 11 degrees-> Fig. 5 Fig. 6 Diagonal axis light ON FF

Claims (3)

[Claims] (1) In an electrostatic recording device that uses a photoconductive photoreceptor and has a charging means and an exposure means, the temperature at or near the surface of the photoconductive photoreceptor is detected, and the charging means is controlled based on the detected temperature signal. An electrostatic recording apparatus characterized in that the surface potential of the photoconductive photoreceptor before exposure is changed according to the detected temperature. (2) Claim 1 in which the surface potential is increased as the detected temperature increases and decreased as the detected temperature decreases.
The electrostatic recording device described in Section 1. (3) Prior to image exposure for forming an electrostatic latent image, the temperature at or near the surface of the photoconductive photoreceptor that is newly subjected to image exposure is detected, and the surface portion of the photoconductive photoreceptor is The electrostatic recording device according to claim 1 or 2, wherein the electrostatic recording device is charged to a one-level charging potential that is controlled and set based on temperature.