JPS62174780A - Electrostatic recording device - Google Patents

Abstract

PURPOSE:To reduce toner consumption and to obtain excellent picture quality at low cost with lightweight constitution by stopping developing operation while the part of a photosensitive body which need not be charged electrostatically owing to the difference in arrangement position between an electrostatic charging electrode and a transfer electrode passes through a development position. CONSTITUTION:The electrostatic charging electrode 2 and transfer electrode 6 are connected to a power source 18 in parallel and turned on and off with the same switch 20. At the time of a start button 20 is turned on, the power source 18 is turned on at time t1 and the photosensitive body 1 is held at a voltage V1 and then at a voltage V2 at time t2 which is a specific time later by the overlap charging of the electrodes 2 and 6, thereby forming an image. The part of the photosensitive body corresponding to the time T1 from the time t1 at the time of the photosensitive surface is at an electrostatic charging position 2a to the time when the front end part of the image reaches the development position 5a and the time T2 from the time when the rear end part of image exposure is at the position 5a of the time when the charging position of the photosensitive body reaches the development position is regarded as the part which need not be charged electrostatically to stop the developing operation. Consequently, the toner attraction from a developing roller 5b to the photosensitive body is stopped to reduce the toner consumption, thereby obtaining excellent picture quality.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electrostatic recording device, and particularly to an improved electrostatic recording device of a type in which a charging electrode and a transfer pole are turned on and off at the same timing.

[Conventional technology]

Conventional electrostatic recording devices have separate high-voltage power supplies for charging electrodes and transfer electrodes, but it is difficult to turn on each power supply.
, OFF were controlled at different timings.

[Problems to be solved by the invention]

Since a high voltage power supply stably outputs a high voltage of several kilovolts, it is both heavy and expensive, and using two of these leads to an increase in the cost of the product. Also, if you control ON and OFF at different timings, the high voltage power supply will turn ON.
, OFF causes noise and increases the chance of disrupting control. To this end, it is conceivable to use one common power source for the charging electrode and the transfer pole, and drive the charging electrode and the transfer pole at the same timing. Due to the difference in the position of the poles, charged parts (
(hereinafter referred to as unnecessary charged portions). When this unnecessary charged portion passes through the development position, a large amount of developer is deposited on the photoreceptor, increasing the amount of developer consumed. Further, there are disadvantages such as increased cleaning load. The present invention aims to improve these drawbacks by 4 degrees.

[Means to solve the problem]

The purpose of this is to turn on the charging electrode and transfer electrode at the same timing.
, an electrostatic recording device that turns off while an unnecessary charged portion of the photoreceptor, which is caused by a difference in the arrangement positions of the charging electrode and the transfer pole with respect to the photoreceptor, passes through a development position;
This is achieved by an electrostatic recording device characterized in that the developing action of the developing device is stopped.

【Example】

An embodiment of the present invention will be described using the configuration diagram in FIG. 1 and the time change curve of the photoreceptor surface potential in FIG. 2. However, the invention is not limited to this embodiment. A charging electrode 2 is provided on the outer periphery of the photoconductor I, which is rotatably provided.
, a focusing light transmitting body 3, a magnetic brush developing device 5, a charging electrode 6, a cleaner 8, and a static elimination lamp 9 as an optical system during image exposure.
is arranged above, and an original table 10 is movable for scanning in synchronization with the movement of the surface of the photoreceptor l. It is set in Noh. Also provided below are conveyance nipping rollers 11 and 12 for feeding the transfer paper 13 as a transfer material, and a conveyance section 14 for conveying to the fixing device 15. In addition, the charging electrode 2 and the transfer pole 6 are connected to a DC high voltage power source 18.
Connections are made to the 1114th column via the N and OFF switch. One current from [the power source] 8 is I to the charged electrode.
cy is shunted, and part of it becomes a radiation current of 1 cb to the back plate, and the other part becomes a radiation current of 1 cd to the photoreceptor drum J, and ltv is shunted to the transfer pole, and a part of it becomes a radiation current of 1 cb to the back plate. radiation current to +tb other -i
l is the radiation current 1td to the drum. Also, Ic
The sum of y and ltv is one. The photoreceptor 1 has a photosensitive layer 1a formed on the outer surface of a conductor layer 1b, and the conductor layer 1b is grounded and connected to the power source 18 through the ground. In this way, the charging electrode 2 and the transfer electrode 6 can be turned on and off at the same time by the same switch 20 from the same power source 18. Further, in this embodiment, the angle between the transfer pole 6 and the static elimination lamp 9 is 130° when viewed from the center of the photoreceptor l.
The static elimination position 9a of the static elimination lamp 9 and the charging position 2a of the charging electrode 2
The angle between the charging electrode 2 and the focusing light transmitting body 3 for image exposure is 30°, the angle between the transmitting body 3 and the developing position 5a is 85°, and the developing Position 5a and transfer pole 6
The angle between them is 85°, but the angle is not particularly limited to this. Furthermore, although the photoreceptor is drum-shaped, it is not limited to this, and it is of course possible to use a belt-shaped photoreceptor. Further, a bias potential is applied to the developing roller 5b of the developing device 5 by a DC power supply 27 with the same polarity as the surface potential of the charged photoreceptor drum. The toner in the developer 25 uniformly fed into the developing device 5 forms a latent image on the photoreceptor 1 due to the appropriately set potential difference between the surface potential of the photoreceptor 1 and the bias potential of the developing drum 5b. The toner image is transferred to the IRJ section, where it is attracted and a toner image that is an IRJ visual image is formed. The power supply 27 is configured so that its output voltage is variable iif. If the voltage is increased and the bias potential of the developing roller 5b is brought closer to the surface potential of the photoreceptor, the toner will not transfer to the photoreceptor drum l. It becomes undeveloped. Next, the operation and effects of this device will be explained. When the high-voltage DC power source 18 is turned on by 4 degrees with the switch 2o, the change in surface potential of the rotating photoreceptor at the charging electrode position 2a with respect to time is shown by the curve in FIG. That is, time t. Shortly after turning on the copy button, the DC high-voltage power supply is turned on at time L1 and the photoconductor is charged at the charging position, and its surface potential maintains V, pol). Superimposed charging of the charging by the pole 6 and the charging by the charging electrode 2 is performed, and V, Pol!・The time is reached when the DC high voltage power supply 18 is turned off. Until then, this surface potential V, volts, is maintained at a desired constant value. Therefore, in order to obtain good image quality with stable image density, the electrostatic recording apparatus of this embodiment is not used for image formation at least from time t to t, and after time 11, the surface potential V, -. Each function was made to work in order to use the range for image formation. This will be explained below using the operation diagram shown in FIG. The photoreceptor used is a cylindrical selenium photoreceptor with a diameter of 50 nanometers and a circumferential length of 1571 mm, so that copies of A3 size or smaller can be made. Of course, the photoreceptor may also be coated with a fr)it semiconductor. It is designed so that A3 size and A4 size copies can be made with a feed of 296 mm, and 1 size and 85 size copies can be made with a feed of 254 mm. In FIG. 3, the vertical axis shows the circumferential length of the photoreceptor and its converted rotation angle. Then, the image exposure start position is set to 0. Also, the horizontal axis is the time axis. Press the copy button at time t. , press I as shown in ■.
The document table, which has been waiting at the IOME position, moves to the start line as shown in ■. On the other hand, at time t1, the high-voltage power supply is turned on, and the transfer pole and charging electrode start charging the photosensitive drum l as shown by ■ and ■'.

[Photoconductor drum located at transfer position 6a in 1]-
At time t, the L company line moves to the charged position 2a, not shown in ■, is superimposed with a surface potential by the charged electrode as shown in ■', and reaches the image exposure position 3a, shown in ■, at time L3. At this point, image exposure of the leading edge of the image is started, and after development shown in ■ and transfer not shown in ■, the leading edge of the image on the photoreceptor moves along the curve of the leading edge of the image, and at time t,... When ′ reaches ■′,
Full image exposure of 84 or 85 format length is completed. Further, in the case of full-image exposure of A3 or A4 size, the exposure is finished when the leading edge of the image reaches the square (■) at time t7. And time L
At time L3, the document table 10, which had moved to the start line (not shown in ■) a little before p, moves in synchronization with the image-exposed tip of the photoreceptor and at the same timing as the curve, as shown in ■. When the state shown in . can be confirmed, and at time 8, (as shown in ψ, the document table lO is on the curve G, and at time t11, II as shown in ■)
It stops at the OMB standby position and completes one cycle of copying. Here, if the image exposure rear end is A3 or A4 size, the curve [
C and complete development at the time t indicated by @
At time tlO shown in , the transfer to the transfer paper is also completely completed. At this time t1°, the high voltage power supply that was ONI for simultaneous charging at time L1 is turned on as shown in ■ and @'.
Make it FF. The period during which the high-voltage power supply is turned on is indicated by hatching on the operation diagram in FIG. The required image exposure and development times are also indicated by hatching in FIG. The charge erase lamp is turned on when the copy is turned on, and is kept on until the main motor is turned off. In addition, in the case of B4.85 format, the rear end of the image exposure is curved r.
・Move on .]', and complete image exposure, development, and transfer at times 17/, 9', and LIO', indicated by ■'', CD'', and @'', Turn off the high voltage power supply
let Here, the difference between the transfer position and the charging position in the distance in the moving direction of the photoconductor -1- is the line speed of the photoconductor or document table = LP-L, < L, -L. The relationship is As shown in the figure, since only a certain range of photoreceptor surface potential is used for image formation, a high-quality image without density unevenness can be obtained. However, in this case, the surface of the photoreceptor due to charging electrodes is not fully charged even after the image exposure of the unnecessary charged area and the rear end of the image in the range from time t to time t when vl is applied to the photoreceptor due to simultaneous charging. The unnecessary charged portions due to the application of potential being continued until the transfer is completed are developed when they reach the development position 5a. Since there is no transfer paper corresponding to this area, the toner on the photoreceptor remains untransferred, which increases the cleaning load on the cleaner and may not be able to clean it completely. Furthermore, the amount of toner consumed increases, making it inefficient. Therefore, it is necessary to prevent such unnecessary charged portions from being developed. Therefore, firstly, the time L1 when the first high voltage power supply is turned on is
Time T from time t+' when the photosensitive surface of the photoreceptor that was at the charging position 2a reaches the developing position 5a to time t4 when the leading edge of the image shown in ■ reaches the developing position 5a shown in ■. Turn off the development function. Second, the time shown in ■, ■'' is, (A size), t,,'
Time Lg (A size), ts' (B size) when the rear end of image exposure in (B size) reaches the development position 5a shown in ■, OD''
From, time T,. Or the high voltage power supply 18 is turned off at TIG'.
The developing function is stopped for the time L1p (A size) when the charging position of the photoreceptor 2 moves to the developing position when the image becomes F, and the time 1', , T, ' until L+t' (B size). In this way, the eleventh and second measures described above are performed. As a means for the above-mentioned treatment, as in this embodiment, the developing device 5
The bias voltage applied to the surface of the developing roller 5b is varied by a variable bias power supply 27 to increase it by the period T, T, or T,' to balance the potential on the surface of the photoreceptor. In another embodiment, the developing device 5 is moved back from the photoreceptor. In this way, the adsorption of toner from the developing roller 5b to the photoreceptor l is stopped, so that unnecessary charging portions are no longer developed. Therefore, unnecessary toner is not consumed in unnecessary development. There is also a method of erasing the unnecessary charged portion by using a neutralizing lamp before the unnecessary charged portion of the photoreceptor reaches the developing position 5a. Effects of the Invention According to the present invention, an expensive DC high-voltage power supply can be used in common for the charging electrode and the transfer electrode, and can be turned on and off at the same timing, and furthermore, unnecessary charging portions are not developed. Since a bias power source can be taken care of, it has become possible to provide an electrostatic recording device that is light, small, low cost, has good image quality, and has good toner consumption efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electrostatic recording device that is an embodiment of the present invention, FIG. 2 is a curve of the photoreceptor surface potential versus time of the embodiment, and FIG. 3 is an operation diagram of the embodiment. It is a diagram (timing chart). I...Photoreceptor 2...Charging electrode 2a...Charging position 3...
・Focusing light transmission body 3a... Image exposure position 5... Developing device 5a... Developing position 5b... Developing roller 6... Transfer pole 6a... Transfer pole position 8.
・・Cleaner 9・Static charge removal lamp 9a・Static charge removal position I3・
...Transfer paper 18...Power supply 20...Switch 25...Developer

Claims (1)

[Claims] This is an electrostatic recording device that turns on and off a charging electrode and a transfer pole at the same timing, and the unnecessary charged portion of the photoconductor caused by the difference in the arrangement position of the charging electrode and the transfer pole with respect to the photoconductor is located at the developing position. An electrostatic recording device characterized in that the developing action of a developing device is stopped during the passage.