JPH0511633B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention detects a weak current generated when toner is transferred from a developing roll to a photoreceptor during development, and adjusts the amount of toner to be replenished according to this detected current. The present invention relates to a toner supply motor control device for a copying machine.

2. Description of the Related Art In conventional electronic copying machines, an electrostatic latent image formed on the surface of a photoreceptor in an exposure process is developed into a toner image in a development process, and this toner image is transferred to paper in a transfer process. In the developing process, the surface of the photoreceptor is developed by a developing roll to which a developing bias is applied, but when toner is transferred from the developing roll to the photoreceptor during development, a weak current is generated in the developing bias application circuit. This weak current is proportional to the amount of toner transferred from the developing roll to the photoconductor, that is, the amount of toner consumed during development, so this current value is detected and a new amount of toner corresponding to this current value is sent to the developing device. By replenishing the toner, the toner concentration of the developer in the developing device will always be constant, thereby making it possible to obtain a copied image with a stable density.

In addition, "automatic image density control method for copying machines" using the above method has already been published in Japanese Patent Application No. 59-274175, Japanese Patent Application No. 59-274176, Japanese Patent Application No. 59-274177, and Japanese Patent Application No. 59-27417.
-274178 and other applications have been filed.

Problems to be Solved by the Invention However, both applications were for "automatic image density control methods for copying machines" and did not disclose specific control devices.

An object of the present invention is to provide a toner supply motor control device for a copying machine for implementing the above-mentioned conventional automatic image density control method.

Means and effects for solving the problem When developing an electrostatic latent image with a developing roll to which a developing bias power supply is applied, a problem occurs when the toner in the developer is transferred from the developing roll to the electrostatic latent image on the photoreceptor. A device that replenishes toner to the developing device by detecting the current with a current detection circuit provided in the developing bias application circuit and controlling the rotation of the toner supply motor according to this current value, detects the toner consumed during development. means for determining whether the amount satisfies the minimum time required to drive the toner supply motor; and if the amount satisfies the minimum time required, the toner supply motor is activated in synchronization with turning on the developing motor; In addition, if the required minimum time is not satisfied, this is stored in the memory, and the value stored in the memory is set as the condition that the minimum time required to drive the toner supply motor is satisfied. By providing a means for controlling the toner supply motor to turn on in synchronization with the turning on of the developing motor when the amount of toner is exhausted, the toner can be reliably supplied to the developing device in an amount commensurate with the amount consumed. Machine toner supply motor control device.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. In the figure, 1 is a photoconductor of a copying machine, 2 is a charger that charges the surface of the photoconductor 1, and 3 is a charger that guides the original image to the surface of the photoconductor 1 to form an electrostatic latent image on the surface of the photoconductor 1. This shows an optical system such as a self-cleaning lens. The electrostatic latent image formed on the surface of the photoreceptor 1 in the exposure process is developed into a toner image by the developing device 4, and then transferred to a sheet 6 fed by a paper feeding device (not shown) in the transfer device 5. The toner image on the paper 6 is transferred and further sent to a fixing device (not shown) by the conveying means 7, so that the toner image on the paper 6 is fixed on the surface of the paper 6. Further, untransferred toner remaining on the surface of the photoreceptor 1 without being transferred to the paper 6 is removed by a cleaning device 8.

On the other hand, in the developing device 4, a developing roll 10 is provided in the housing 4a in close proximity to the photoreceptor 1. The developing roll 10 has a slit 1 rotated in the direction of the arrow by a developing motor 18 around a magnetic roll 10a having magnetic poles arranged as shown in FIG.
0b, the developing bias application circuit 11
At the same time, the developing bias power source 12 is applied, and the magnetic action of the magnet roll 10a causes the sleeve 1 to
The developer in the housing 4a is adsorbed on the surface of the housing 4a in the form of a brush. Further, the developer adsorbed on the surface of the sleeve 10b is trimmed by the trimming bar 13 so that the spike height is constant, and then reaches the photoreceptor 1, whereupon the electrostatic latent image formed on the surface of the photoreceptor 1 is removed. When the toner is transferred from the developing roll 10 to the photoreceptor 1,
A weak current flows through the developing bias circuit 11 as follows.

That is, there is usually a gap of about 1.0 to 1.5 mm between the photoreceptor 1 and the developing roll 10, as shown in FIG. It is filled with sufficiently insulating toner that is electrostatically attracted to the carrier. At this time, the toner and the carrier, which have a certain charge due to triboelectric charging, are electrically balanced, but the amount of charge that the electrostatic latent image has when it comes into contact with the surface of the photoreceptor 1 on which the electrostatic latent image is formed. Toner in the developer is transferred to the photoreceptor 1 side in an amount corresponding to the amount. As a result, the charge on the toner particles disappears from the developing roll 10,
In order to replenish this, a weak current flows to the developing roll 10. This weak current is proportional to the amount of toner transferred from the developing roll 10 to the photoreceptor 1 during development, that is, the amount of toner consumed during development.
The current is detected by a current detector 14 provided in the developing bias application circuit 11, and is input to a control device 15 consisting of a microcomputer.

On the other hand, a toner supply motor 17 that drives a toner supply auger 16 that supplies toner to the developing device 4 is connected to the output side of the control device 15 . This toner supply motor 17 is controlled by the control device 15.
The toner supply auger 16 is started to rotate in response to an ON signal from the developing device 4, and the toner supply auger 16 is driven by the developing device 4 for the rotation time.
However, due to the performance of the motor used, unless the on time is 0.5 seconds or more, substantially no toner is supplied.

Next, to explain this with reference to FIG. 4, the developing motor 18 which drives the developing roll 10 is
Repeat on and off as shown in Figure a. On the other hand, since the toner supply motor 17 is rotated by the ON signal output from the control device 15 for a time corresponding to the amount of toner consumed during development, the ON time is irregular as shown in FIG. 4b. Become. Furthermore, since the amount of toner consumed during development is small, when a short signal of, for example, 0.5 seconds or less is input from the control device 15 as shown by arrow A in FIG. 4b, the toner supply motor 1
7 cannot follow this and hardly rotates,
Toner is not replenished. As a result, when a document with a low image occupancy rate is successively copied, toner is hardly replenished, resulting in a shortage of toner in the developing device 4 and a decrease in the density of the copied image.

In this invention, in order to prevent the above-mentioned problem, the toner supply motor 17 is turned on at the rising time when the developing motor 18 is turned on, and the toner supply motor 17 is set to turn on the toner supply motor 17.
For example, when the toner corresponding to the rotation for 0.5 seconds or more is consumed during development. As a result, the toner supply motor 17 starts rotating as the developing motor 18 turns on, as shown in FIG. toner can be reliably supplied to the developing device 4. In addition, if the toner consumption amount is less than the minimum rotation time of the toner supply motor 17, it is stored in the memory in the control device 15, and the value stored in the memory is used as the toner supply motor 1.
When the conditions for rotating the toner supply motor 7 are satisfied, the output is output to the toner supply motor 17, and the rotation of the toner supply motor 17 is controlled.

In the above embodiment, the minimum ON time of the toner supply motor 17 was set to 0.5 seconds, but this may of course vary depending on the motor used.

Effects of the Invention As detailed above, this invention provides that when an electrostatic latent image is developed with a developing roll to which a developing bias power is applied, toner in the developer is transferred from the developing roll to the electrostatic latent image on the photoreceptor. The current generated in the developing bias application circuit is detected by a current detection circuit provided in the developing bias application circuit, and the toner supply motor 17 is controlled according to this current value.
A means for determining whether the amount of toner consumed during development satisfies the minimum time required to drive the toner supply motor 17 in a device that replenishes toner to the developing device 4 by controlling the rotation of the toner supply motor 17. If the required minimum time is satisfied, the toner supply motor 1 is turned on in synchronization with the turning on of the developing motor 18.
7 is turned on, and if the required minimum time is not satisfied, this is stored in the memory, and the value stored in the memory is used to turn on the toner supply motor 1.
By providing means for controlling the toner supply motor 17 so that it is turned on in synchronization with the turning on of the developing motor 18 when the minimum time required to drive the toner supply motor 17 is satisfied, the image occupancy rate can be reduced. Even when a document with a small amount of toner is continuously copied, an amount of toner commensurate with consumption can be reliably supplied to the developing device. This makes it possible to always obtain copies with constant image density.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall configuration diagram, FIG. 2 is an explanatory diagram of the developing device and control system, FIG. 3 is a block diagram of the inventive device, and FIGS. 4 a and b. 5a and 5b are timing charts showing the same effect. 4 is a developing device, 11 is a developing bias application circuit,
17 is a toner supply motor, and 18 is a developing motor.

Claims (1)

[Claims] 1. When developing an electrostatic latent image with a developing roll to which a developing bias power supply is applied, a developing bias application circuit is provided with a current generated when toner in the developer is transferred from the developing roll to the electrostatic latent image on the photoreceptor. In a device that replenishes toner to the developing device 4 by detecting it with a current detection circuit and controlling the rotation of the toner supply motor 17 according to this current value, the amount of toner consumed during development is detected by the toner supply motor 17.
means for determining whether or not the minimum time required to drive the toner supply motor 17 is satisfied; In addition, if the required minimum time is not satisfied, this is stored in the memory, and when the value stored in the memory satisfies the minimum time required to drive the toner supply motor 17. , the developing motor 18
1. A toner supply motor control device for a copying machine, comprising means for controlling a toner supply motor 17 to be turned on in synchronization with turning on of the toner supply motor 17.