JPS61235874A - Toner supply motor controller of copying machine - Google Patents

Abstract

PURPOSE:To supply toner to a developing device securely by an amount suitable to consumption by turning on a toner supply motor in synchronism with the turning-on operation of a developing motor when the condition of a minimum time required to drive the toner supply motor is satisfied. CONSTITUTION:The amount of toner which is consumed during development is detected by a current detecting means provided to a developing bias applying circuit 11 to control the rotation of the toner supply motor 17 according to the current value. The toner supply motor 17 is turned on while the developing motor 18 is driven, and this toner supply motor 17 is driven on condition that toner is consumed during the development by an amount which is large enough to rotate the toner supply motor 17 for, for example, >=0.5sec. Consequently, even when an original having a small image occupation rate is copied continuously, toner corresponding to consumption is supplied securely to a developing device and copies having constant image density are obtained.

Description

Detailed Description of the Invention Industrial Application This invention detects a weak current generated by the transfer of toner from the developing roll to the photoreceptor during development, and adjusts the amount of toner replenishment 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 transferred 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.

Furthermore, "automatic image density control method for copying machines" using the above method has already been published in Japanese Patent Application No. 59-274175.
-274176, Japanese Patent Application No. 59-274177, Japanese Patent Application No. 59-274178, etc.

Problems to be Solved by the Invention However, all applications are for "Automatic Image Density Control Method for Copying Machines"
The application did not disclose a specific control device.

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 for solving the problem and its operation During development, a current detector installed in the development bias circuit detects the weak current generated by the transfer of toner from the development roll to the photoreceptor, and supplies toner according to this current value. A condition in which the amount of toner consumed during development satisfies the minimum time required to drive the toner supply motor in a device that supplies toner in an amount commensurate with the amount of toner consumed to the developing device by controlling the rotation of the motor. By controlling the toner supply motor so that the toner supply motor turns on in synchronization with the turning on of the developing motor when Machine donor feed 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 the 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 10. Indicates an optical system such as a self-hock lens. The electrostatic latent image formed on the surface of the photoreceptor 10 in the exposure process is developed into a toner image by the developing device 4, and then transferred to the paper 6 fed by a paper feeding device (not shown) in the transfer device 50, and then The toner image on the paper 6 is sent to a fixing device (not shown) by the conveying means 7 and fixed on the surface of the paper 6. Further, untransferred toner remaining on the surface of the photoreceptor l without being transferred to the paper 6 is removed by a cleaning device 8.

On the other hand, the developing device 4 is provided with a developing roll 10 adjacent to the inner photoreceptor I of the housing 4α. As shown in FIG. 2, the developing roll 10 has a structure in which a slip 10b, which is rotated in the direction of the arrow by a developing motor 18, is provided around a magnetic roll log in which magnetic poles are arranged. 12 is being applied, and the sleeve Jo is moved by the magnetic action of the magnet roll 10α.
The developer in the housing 4α is adsorbed in the form of a brush on the surface of b. Further, the developer adsorbed on the surface of the sleeve L (l) is trimmed by a trimmer 13 so that the spike height is constant, and then reaches the photoreceptor 1, where an electrostatic latent image is formed on the surface of the photoreceptor 10. 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.

In other words, there is a second
As shown in the figure, there is usually a gap of 1.0 to 1.5 degrees, and during development, this gap is electrostatically attracted to the carrier due to frictional electrification between the carrier and the carrier, which has sufficient insulating properties. The area is filled with a sufficiently insulating toner. At this time, the toner and carrier, which have a certain charge due to triboelectric charging, are electrically balanced, but when they come into contact with the surface of the photoreceptor 1 on which the electrostatic latent image is formed, the amount of charge that the electrostatic latent image has Toner in the developer is transferred to the photoreceptor 1 side in an amount corresponding to the amount. As a result, the amount of charge on the toner particles and the charge on the developing roll 10 disappears, and a weak current flows to the developing row/I/IO to replenish this. This weak current is proportional to the amount of toner 9 transferred from the developing roll 10 to the photoreceptor 1 during development, that is, the amount of toner consumed by development, and is detected by the current detector 14 provided in the developing bias application circuit 11. The data is then taken into 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 . The toner supply motor 17 starts rotating in response to an ON signal from the control device 15, drives the toner supply auger 16, and supplies toner to the developing device 4 for the rotation time; however, due to the performance of the motor used, the ON time is For example, if it is not longer than 005 seconds,
Substantially no toner is supplied.

Next, this will be explained with reference to FIG. 4. The developing motor I8 that drives the developing roll 10 is repeatedly turned on and off as shown in FIG. 4 (α) for each copy. 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. 4 (Ch). becomes.

In addition, since the amount of toner consumed during development is small, the control device 15
For example, if a short signal of 0°5 seconds or less is input as shown by arrow A in FIG. 4(b), the toner supply motor 17
cannot follow this movement and hardly rotates, so 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 problems, the developing motor 1
At the same time, the toner supply motor 17 is turned on at the rising time when the toner supply motor 17 is turned on, and the toner supply motor 17 is turned on at the rising time when the toner supply motor 17 is turned on. and when it was consumed.

As a result, the toner supply motor 17 starts rotating as the developing motor 18 turns on, as shown in FIG. 5<b>.
In addition, since the rotation time is 0.5 seconds or more, it is possible to ensure that an amount of toner commensurate with the amount of toner consumed during development is delivered to the developing device 4.
It will be possible to supply to Further, 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 when the value stored in the memory satisfies the condition for rotating the toner supply motor I7, the toner supply motor I7 is The rotation control of the toner supply moke 17 is performed.

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 described in detail above, the present invention detects the amount of toner consumed during development by a current detection means provided in the development bias application circuit, and replenishes toner according to this current value. Only when the toner supply motor satisfies the minimum on-time required to replenish toner, the toner supply motor is rotated in synchronization with the development motor off and replenishes toner to the developing device. Therefore, even when a document with a low image occupancy rate 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 FIG. 4 (α) , (b) and FIG. 5(α), (b) 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] The amount of toner consumed during development is calculated by the development bias application circuit 11.
By detecting the current value with a current detection means provided in the toner supply motor 17 and controlling the rotation of the toner supply motor 17 according to the current value,
In the device that replenishes toner to the developing device 4, when the amount of toner consumed during development satisfies the minimum time required to drive the toner supply motor 17, it is synchronized with the turning on of the developing motor 18. Toner supply motor 17
1. A toner supply motor control device for a copying machine, characterized in that the toner supply motor control device controls the toner supply motor to be turned on.