JPS59128566A - Dry type copying machine - Google Patents

Abstract

PURPOSE:To keep the ratio of recovered toner in a developing device and replenished toner constant by replenishing forcibly a specified quantity of toner according to single copy or continuous plural copies in addition to toner replenishment proportionate to number of copies, size of the copy etc. CONSTITUTION:In a copying machine, interval of image formed on a toner image forming body is different depending on whether the copy is single or plural. In the case of single copy, the image interval is (b) when the length of image forming part is (a). In the case of continuous plural copies, image interval is (c), and image interval between continuous plural copies and next copy is (d), and (d)=(b). Recycle replenishing of recovered toner is made while the toner forming body is driven, and replenishing of toner is made in proportion to the number of copies. Accordingly, proportion of recovered toner becomes higher in the case of single copy. Therefore, specified quantity of toner is replenished for balancing when image interval is (b) or (d).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a dry type copying machine, particularly when the image interval between images formed on a toner image forming body is not only one copy but also continuous copying of multiple copies. The present invention relates to an improvement in a copying machine in which, in a steady state, a developing device is supplied with collected toner from a cleaning device and toner is replenished from a toner replenishing device as the copying drive is performed.

[Prior art]

As shown in Figure 1, the distance between images formed on the toner image forming body is narrower when making continuous copies of multiple copies than when copying a single copy. It is known as a compatible demand-type copying machine.

In FIG. 1, a is the driving length of the surface of the toner image forming body on which image formation is performed, b is the image interval in the case of one-copy copying,
C is the image interval in continuous quick copying of multiple copies, d is the image interval between continuous copying of multiple copies and the next copy, and this image interval d is the same as the image interval in single copying.

On the other hand, in order to improve toner utilization efficiency, there is a dry copying machine in which collected toner from a cleaning device is supplied to a developing device along with toner replenishment from a toner replenishing device, for example, by a device as shown in FIG. is also known.

In FIG. 2, numeral 2 is a magnet roller provided at one end of a drum-shaped toner image forming member so as to rotate together with the toner image forming member, and 2 is a magnet roller suspended between the magnet roller 1 and the supply roller 3. Recycling belt, 4 is a developing device, 5 is a carrier supply sleeve that is provided integrally with the developing sleeve of the developing device 4 and supplies the carrier in the developer to the recycling belt 2, and 6 is a recycling belt 2 for collecting toner collected from the cleaning device. A recovery conveyor screw 7 that collects the collected toner on the side is a recovered toner sending section that sends out the collected recovered toner to the recycling belt 2. The above is a recycling device for recovered toner. In this recycling device, when the magnets a and l rotate in the direction of the arrow together with the toner image forming body, the recycle belt 2 rotates in the direction of the arrow, and the surface of the recycle belt 2 is rotated in the direction of the arrow. The carrier that is attached to the carrier supply sleeve 5 and moves is attracted by the magnetic force of the magnet IA embedded in the magnet roller 1, and the attracted carrier is carried along with the rotation of the recycling belt 2 to the collected toner delivery section. 7, the collected toner is received and taken up, and when it reaches a position where it comes off the surface of the magnet roller 1, it is released from the attraction by the magnet IA and is then carried on the recycling belt 2. Therefore, the toner is transported on the recycling belt 2. From the recycling belt 2 to the developing device fFj at the position of the roller 3
The recovered toner is supplied by falling onto the supply conveyor screw 8 in the toner 4.

Reference numeral 9 denotes a toner replenishment device, in which a toner delivery plate 10 reciprocates in the direction of the arrow a number of times proportional to the number of copies or the copy paper size, etc., and the toner provided on the toner delivery plate 10 is The delivery hole 10A moves in and out between the toner hopper 9A and the toner delivery chamber 9B, and the toner filled in the toner delivery hole 10A in the toner hopper 9A falls from the toner delivery hole 10A in the toner delivery chamber 9B. , which supplies replenishment toner onto a supply conveyor screw 8 within the developing device. Incidentally, reference numeral 11 denotes a push-out ball that pushes out the toner from the toner delivery hole 10A and causes it to fall.

Furthermore, a dry copying machine is also known, which uses the above-mentioned demand-type copying machine with a toner supply device as shown in Fig. 2 to speed up copying and efficiently reuse recovered toner. . However, in such copying machines, the characteristics of the collected toner in terms of development performance, transfer performance, etc. have changed compared to the replenishment toner, and the recycling supply of the collected toner is difficult to drive the toner image forming body as described above. As a general rule, the supply of replenishment toner is done in proportion to the number of copies to be made, so the image interval is smaller when copying a single copy and when copying multiple copies continuously. Since the supply ratio of toner during recovery increases as the width increases, in the case of one-copy copying, the image density on the toner image forming body or in the copy gradually decreases compared to one continuous copying as shown in FIG. decrease or
There are problems in that dirt and poor cleaning occur.

FIG. 6 shows an experimental example of one-copy copying and continuous copying. Even if the image density, that is, the development density, is kept constant in the case of continuous copying, if one copy copying is repeated, as explained above, Since the ratio of recovered toner in the developer increases, the developer density gradually decreases.

[Purpose of the invention]

The present invention is intended to solve the above-mentioned problem in conventional demand-type copying machines that recycle collected toner, that is, when copying for one copy, the ratio of collected toner increases and the image density decreases. The object of the present invention is to provide a demand-type copying machine that uses toner recycling and can maintain a constant image density even when copying a single copy.

[Structure of the invention]

In the present invention, the image interval formed on the toner image forming body is 1
Continuous copying of multiple copies is more difficult than copying in sets, and in a steady state, the developing device is supplied with collected toner from the cleaning device and toner from the toner replenishing device as the copying drive is being performed. This dry type copying machine is characterized in that a predetermined amount of toner is forcibly replenished from a toner replenishing device to a developing device every time the copying process continues.

That is, the dry copying machine of the present invention, in a steady state,
In addition to toner replenishment proportional to the number of copies, copy paper size, etc., a predetermined amount of toner is forcibly replenished at a time when the image interval is in the range of d and d in Figure 1. This forced replenishment prevents the supply ratio of recovered toner and replenishment toner from changing whether copying is done in one copy or in continuous copying.

〔Example〕

The above-described toner replenishment control in the copying machine of the present invention can be carried out by using a control circuit as shown in FIG. 3 and performing control operations as shown in FIG. 4. .

In FIG. 3, PS is a density information input terminal for controlling toner replenishment based on the density information of the toner image obtained by forming a standard image on a toner image forming body and developing it, and 12 is a density information input terminal during copying drive. The comparator 13 is related to toner replenishment control, which will be described later.The main control circuit is composed of a microcomputer and controls the entire copying machine. When the density information is below a predetermined value, a toner replenishment command is issued based on the output information of the comparator 12 to replenish toner during the copying drive. 1
If the output information of 3 indicates that the density information is normal, issue a command to force the toner replenishment of a predetermined amount of toner, and then the output information of the comparator 13 indicates that the density information is abnormal. If it shows that the amount is high, the above-mentioned forced replenishment is controlled to be suspended.

Note that toner replenishment control during copying drive based on the output 'i'# information of the comparator 12 is known per se.

Next, the forced replenishment of toner in the present invention will be explained with reference to FIG. 4.

FIG. 4 is a flowchart showing the control operation of the main control circuit. When the copy drive is started, the main control circuit determines whether or not copying of the set number of copies is completed each time image formation or copying is performed. If not, it is immediately checked whether the end flag is "1" or not, and if not, the forced replenishment flag for a predetermined amount of toner is set to O. Then, when the image formation or copying reaches the set number of copies, it is checked whether the optical unit has returned to the home position "HP", and when it returns to "HP", the end flag is set to "1".
”, at that point the output of comparator 13 becomes “
If it is "LOW", that is, the image density is normal, then the forced replenishment flag is set to "'1".
If it is not "1", that is, the forced replenishment has started, the forced replenishment timer is set, the forced replenishment magnetic clutch (No) is turned on, and the forced replenishment flag is set to "1". Since the forced replenishment of the predetermined amount of toner has started, continue to wait until the forced replenishment timer counts up, and when the timer counts up, turn off the forced replenishment M (3) to replenish the predetermined amount of toner for each successive copy drive. Forced replenishment is performed when the copying drive is stopped.

In this main control circuit, even if the image formation reaches the set number of copies, when the output of the comparator 13 is "LOW", that is, when the image density is not normal and high, forced replenishment of a predetermined amount of toner is suspended.

FIG. 5 is a time chart of forced replenishment performed by the control operation shown in FIG.
It will be held at time e. Note that the line extending to the right of the "HP" line indicates the driving time for ejecting the last copy sheet.

〔Effect of the invention〕

Since the copying machine of the present invention performs toner replenishment control as described above, the supply ratio of recovered toner and replenishment toner is constant whether copying one copy or continuous copying.
As shown in the figure, even in the case of one-copy copying, the effect of stabilizing the image density is achieved in the same way as in continuous copying.

Note that the present invention is not limited to the example described above, and may be such that, for example, forced replenishment of a predetermined amount of toner for each successive copy drive is performed based on a start signal from a copy start button.

[Brief explanation of drawings]

FIG. 1 is a chart showing the interval between images formed on a toner image forming body, FIG. 2 is a schematic side view of the configuration of a toner supply device to a developing device, and FIG. 3 is a control used in the copying machine of the present invention. A schematic diagram of the circuit, FIG. 4 is a flowchart of the control operation performed by the control circuit of FIG. 3, FIG. 5 is a time chart of forced replenishment performed according to the flowchart of FIG. 4, and FIG. FIG. 7 is a graph of image density changes in a demand-type copying machine for recycling. FIG. b, c, d...image gap, 1...magnetic roller,
2... Recycle belt, 3... Supply section roller, 4
...Developing device, 5.Carrier supply sleeve, 6.Recovery conveyor screw, 7.Recovered toner sending section, 8.Supply m conveyor screw, 9..Toner supply device, 1o ...toner delivery board,
11... Push ball, PS... Density information input terminal, 12, 13... Comparator. Patent Applicant: Konishiroku Photo Industry Co., Ltd. *1 Figure 5 Figure 6 Sekiho Seimaki - 10

Claims (1)

[Scope of Claims] (1) The interval between images formed on a toner image forming body is narrower in continuous copying of multiple copies than in the case of copying one copy, and in a steady state, development occurs as copying drives. In a copying machine in which the device is supplied with recovered toner from a cleaning device and toner from a toner replenishing device, a predetermined amount of toner is forcibly replenished from the toner replenishing device to the developing device every time a continuous copy is driven. A dry type copying machine characterized by the following features: (2) The dry type copying machine according to claim 1, wherein the forcible replenishment of the predetermined amount of toner is performed when the copying drive is stopped. (5) The dry type copying machine according to claim 1, wherein the forcible replenishment of the predetermined amount of toner is performed at the start of copying drive.