JPH10123906A - Electrophotographic printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to substantially continue printing without having a printing stoppage state caused by an error, even in the case of printing an image having a high printing density pattern by enlarging the printing space in the case in which the consumption of toner used for forming a toner image is larger than the replenished toner quantity. SOLUTION: In the case in which the toner quantity used for forming toner image is larger than the quantity of the toner replenished by a toner replenishing device 6 at printing the image having a high printing density patter. It is judged by a microcomputer 8 that the toner consumption is larger than the replenished toner quantity when the toner concentration Tc becomes equal to or below the concentration value Tm in an appropriate extent, then, a control for enlarging the printing distance is performed by the computer 8 on order to suppress the toner consumption. The control for enlarging the printing space is performed by discontinuing to form an electrostatic latent image, that is, by discontinuing to transfer printing information from the host device. The photoreceptor 2 and a developing roll 3 are continuously rotated on this state, but, the electrostatic latent image is not formed, so that the consumption of the toner is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic printing apparatus.

[0002]

2. Description of the Related Art A conventional example will be described with reference to a flowchart shown in FIG.

[0003] The two-component magnetic brush developing system is a method in which a toner as powder ink and a carrier bead as magnetic particles in a developing machine are used to form a toner on an electrostatic latent image formed on the surface of an image carrier such as a photoreceptor. And develops it as a toner image. In such a developing method, the mixing ratio (toner density) of the toner and the carrier beads in the developing machine is an important factor in print quality. Therefore, in order to obtain a good image, it is necessary to control the toner density in the developing machine within an appropriate range. Therefore, in the conventional electrophotographic printing apparatus, a toner sensor for detecting the toner concentration Tc of the developing device is provided, and the level and the rate of change of the toner concentration Tc, the replenishment amount per time, and the like are monitored. Even if the toner inside is consumed, the toner concentration is controlled by appropriately replenishing the toner so as to keep the toner concentration Tc within an appropriate range or by stopping the replenishment of the toner. Further, if the toner density Tc is lower than the minimum density Te in the appropriate range even after the toner density control is performed, it is determined that an error has occurred, and control is performed to stop printing.

[0004]

In an electrophotographic printing apparatus of this type, when an image having a high printing density is printed, the amount of toner consumed for forming a toner image is reduced by a toner replenishing apparatus. In some cases, the amount becomes larger than the supplied toner amount. In such a case, conventionally, the toner density Tc
When the toner density Tc becomes lower than the minimum density Te in the appropriate range, this is determined to be an error and printing is stopped.

An object of the present invention is to print an image of a pattern having a high print density, and the amount of toner consumed for forming a toner image becomes larger than the amount of toner supplied by a toner supply device. An object of the present invention is to provide an electrophotographic printing apparatus capable of substantially continuing printing without intervening a printing stop state due to an error even in the case of an error.

[0006]

The above object is achieved by providing a means for extending a printing interval when the amount of toner consumed for forming a toner image is larger than the amount of toner supplied by a toner supply device. Is done.

Further, as a reference value for controlling the toner density, a first reference value (Te) indicating the lowest value and a second reference value (Tm) set to a value higher than the first reference value. This is achieved by having a means for enlarging the printing interval when the toner concentration actual value (Tc) measured by the toner sensor is equal to or more than the first reference value (Te) and less than the second reference value (Tm). You.

[0008]

1 and 2 show an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 is a block diagram of a main part of an electrophotographic printing apparatus according to the present invention, and FIG. 2 is a control flowchart.

In FIG. 1, reference numeral 1 denotes a developer accommodating section for accommodating a two-component developer composed of a toner and a carrier. A developing roll 3 is provided at a portion of the developer container 1 facing the photoconductor 2.
Is rotatably supported, forms a magnetic brush of the two-component developer on the surface of the developing roll 3, and supplies toner to an electrostatic latent image formed on the photoconductor 2 by the magnetic brush. 2, a toner image is formed.

A toner sensor 4 for monitoring the toner concentration in the two-component developer is provided in the developer container 1. A toner hopper 5 for storing toner is provided in the vicinity of the developer accommodating section 1, and the toner in the toner hopper 5 is supplied to the developer accommodating section 6 by operating the toner replenishing device 6 based on an output signal of the toner sensor 4. Replenish to 1.

Reference numeral 7 denotes a motor for operating the toner replenishing device 6, and reference numeral 8 denotes a microcomputer for controlling the toner density Tc to a value within an appropriate range.

The microcomputer 8 controls the toner density as shown in FIG. In this toner concentration control, the level and change rate of the toner concentration Tc, the amount of toner replenished per unit time, and the like are monitored, and even if the toner in the developing device is consumed by the printing operation, the toner concentration Tc falls within an appropriate range. Then, the motor 7 is driven to supply toner to the developer accommodating section 1 or the motor 7 is stopped to stop toner supply. Here, the amount of toner consumed for forming a toner image by printing an image of a pattern having a high print density is:
When the toner amount is larger than the toner amount supplied by the toner supply device 6, the microcomputer 8 determines that the toner consumption amount is larger than the toner supply amount when the toner concentration Tc falls below the density value Tm within an appropriate range. Then, control is performed to extend the printing interval in order to suppress the toner consumption.

The control to extend the printing interval is to form an electrostatic latent image when the amount of toner consumed for forming the toner image is larger than the amount of toner supplied by the toner replenishing device 6, that is, to perform electrophotography from a host device. This is performed by stopping the sending of print information to the printing apparatus. In this state, the photoconductor 2 and the developing roll 3 continue to rotate, but since the feeding of print information is stopped, the formation of an electrostatic latent image on the photoconductor 2 is not performed. Consumption is reduced. In this state, the recording paper (not shown) is not conveyed and stands by at a predetermined position.

In this embodiment, the control for extending the printing interval is performed using the timer TM. First, after the printing operation is started, the toner density is controlled, and then the timer TM
Check the value of. If the timer TM is not “0”, the timer TM counts down and proceeds to the next process when the timer TM becomes “0”. When the timer TM does not become "0", the process returns to the toner density control. Then, during the timer countdown, the control is such that the next printing is not started.

Next, it is checked whether the toner concentration Tc is within a proper range. If the toner density Tc is a value smaller than the minimum density Te in the appropriate range, it is determined that an error has occurred.
If the toner density Tc is equal to or higher than the minimum density Te in the appropriate range, it is checked whether or not the printing interval is to be increased. Here, if the toner density Tc is smaller than Tm, the timer count value T is used to extend the printing interval.
M0 is set in the timer TM, and the process returns to the toner density control.

If the toner concentration Tc is equal to or higher than Tm, a printing completion check is performed. During the printing operation, the toner density control and the control for increasing the printing interval are repeatedly performed. Therefore, if the printing is not completed, the process returns to the toner density control.
When printing is completed, toner is not consumed.
It is not necessary to perform toner density control and control for extending the printing interval.

According to the control of FIG. 2, the next printing is not performed while the timer TM is counting down, so that the interval between the first printing and the second printing is increased. During the period in which the printing is not performed, the toner is not consumed, but the toner density control is performed in the same manner as before the printing interval is increased, and the toner is supplied. Therefore, the toner density Tc is recovered by the length of the printing interval.

[0019]

As described above, according to the present invention, when printing an image of a pattern having a high print density,
Provided is an electrophotographic printing apparatus capable of continuing printing without causing an error even when the amount of toner consumed for forming a toner image becomes larger than the amount of toner supplied by a toner supply device. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an electrophotographic printing apparatus according to the present invention.

FIG. 2 is a control flowchart of the present invention.

FIG. 3 is a conventional control flowchart.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developer accommodation part, 2 ... Photoconductor, 3 ... Development roll, 4 ...
Toner sensor, 5: toner hopper, 6: toner replenishing device, 7: motor, 8: microcomputer.

Claims (3)

[Claims] A developer container for storing a two-component developer comprising a toner and a carrier; a developing roll rotatably supported by the developer container and forming a magnetic brush of the two-component developer; A toner sensor provided in the developer accommodating portion, for monitoring a toner concentration in the two-component developer; a toner hopper provided near the developer accommodating portion, for accommodating toner; and an output signal of the toner sensor. A toner replenishing device for replenishing toner in the toner hopper to the developer accommodating portion based on the toner supplied to the electrostatic latent image formed on the image carrier by the magnetic brush, In an electrophotographic printing apparatus that forms an image, a printing interval is set when the amount of toner consumed for forming the toner image is larger than the amount of toner supplied by the toner supply device. An electrophotographic printing apparatus, comprising: means for enlarging. 2. A developer accommodating portion for accommodating a two-component developer comprising a toner and a carrier, a developing roll rotatably supported by the developer accommodating portion and forming a magnetic brush made of the two-component developer; A toner sensor provided in the developer accommodating portion, for monitoring a toner concentration in the two-component developer; a toner hopper provided near the developer accommodating portion, for accommodating toner; and an output signal of the toner sensor. A toner replenishing device for replenishing toner in the toner hopper to the developer accommodating portion based on the toner supplied to the electrostatic latent image formed on the image carrier by the magnetic brush, In the electrophotographic printing apparatus for forming an image, a first reference value (Te) indicating a minimum value and a value higher than the first reference value are set as reference values for controlling the toner density. The second reference value having a (Tm), the toner sensor toner density measured value by (Tc) is a first reference value
An electrophotographic printing apparatus comprising: means for enlarging a printing interval when the value is equal to or more than (Te) and less than a second reference value (Tm). 3. An electrophotographic printing apparatus according to claim 1, wherein said printing interval expanding means is means for executing / stopping the formation of said electrostatic latent image.