JP2914514B2 - Toner density control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner density control device for controlling a toner density of a developing device for visualizing an electrostatic latent image.

[Conventional technology]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine that develops an electrostatic latent image formed on a photoreceptor with a toner, in order to maintain a proper toner density, when the toner density in a tank of the developing apparatus falls below a certain control level. The toner is supplied from the hopper 371 to the tank 373 (see FIG. 3). In such an image forming apparatus, for example, in a case where a document is continuously copied, the developed image may be thinned because the toner supply amount cannot keep up with the toner consumption amount.

For this reason, a second control level is set between the control level and the empty level, and when the toner density falls below the second control level, the copying operation is temporarily stopped to supply toner, and the toner density is reduced to a certain level. (Japanese Patent Application Laid-Open No. Sho 62-105173, Japanese Patent Application Laid-Open No.
-156782).

[Problems to be solved by the invention]

However, in the above-described toner density control device, it takes a long time after the copying operation is stopped to recover to the predetermined level, and the copying operation is stopped for a long time. In other words, when continuous copying is performed at intervals of several seconds in a case where the toner consumption is large, such as continuous copying of a document having a large black solid area, the user may stop for several tens of seconds to several minutes. However, when the amount of toner remaining in the hopper 371 decreases, the amount of toner supplied to the tank 373 decreases. In this case, it is necessary to notify the user that the toner needs to be replenished to the hopper 371 and to prevent the copying from being performed at a low density for a long time.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem, and to provide a toner density control device having a short stop time for recovering the toner density at the time of recording.

[Means for solving the problem]

In order to achieve the above object, the present invention is directed to an image forming apparatus in which recording is performed while toner is supplied while a detected toner concentration is between a control level and an empty level. A rest level setting means for setting a rest level, an altitude discriminating means for judging whether or not the toner density is equal to or lower than the rest level, and a recording operation for suspending the recording operation for a preset time each time one recording is completed. A pausing means; and a control means for driving the recording operation pausing means when the toner concentration does not change above the pausing level.

According to a second aspect of the present invention, a detection level setting means for setting a detection level between a pause level and an empty level, a second density determination means for determining whether or not the toner density is equal to or lower than the detection level, and the toner density And a display means for performing an empty display when the value changes to below the detection level.

Further, the present invention further comprises a stopping means for stopping the recording operation when the toner concentration changes below the detection level.

[Action]

According to the toner density control device having the above-described configuration, when the toner density changes below the pause level set between the control level and the empty level, the recording operation is paused for a preset time, and after the time has elapsed, the recording operation is stopped. To resume.
This pause of the recording operation is always performed every time one recording is completed when the toner concentration becomes lower than the pause level.

Further, according to the toner concentration control device of the second aspect, when the toner concentration changes below the detection level set between the pause level and the empty level, an empty display is performed.

Further, according to the toner density control device of the third aspect, when the toner density changes below the detection level, the recording operation is stopped.

〔Example〕

FIG. 2 is a configuration diagram of a digital copying machine (image forming apparatus) to which the toner density control device according to the present invention is applied.

The copying machine 21 has a contact glass 22 and a document holder 23 on its upper surface, and has an optical mechanism L and an image forming means P inside.

The optical mechanism L includes a light source including a halogen lamp 24 and a reflection plate 25, reflection mirrors 26, 27, and 28, a lens unit 29, and a solid-state imaging device (hereinafter, referred to as a CCD) 30. And
When the recording (copy) operation is started, the light from the light source is reflected by the original placed on the contact glass 22, and the reflected light is guided to the lens unit 29 via the reflecting mirrors 26, 27, and 28. After that, it is read by CCD30.

The image forming means P includes a laser generator 31 and a polygon mirror.
32, reflector 33, photoconductor 34, charging device 35, blank lamp
36, a developing device 37, a transfer device 38, a separating device 39, a cleaning device 40, and the like. Then, laser light corresponding to the read original is emitted from the laser generator 31.
On the other hand, the surface of the photoreceptor 34 is uniformly charged by the charging device 35, is exposed to the laser light passing through the polygon mirror 32 and the reflection mirror 33, and an electrostatic latent image is formed. Thereafter, the electrostatic latent image developed with the toner by the developing device 37 is transferred to the transfer device.
After being transferred to the paper by 38, the photoreceptor is
Separated from 34.

Further, as a paper feeding mechanism, a paper feeding cassette 41, a paper feeding roller 42, and a registration roller pair 43 are arranged in this order from the upstream in the feeding direction, whereby the paper is fed to the photoconductor 34, and the transfer is performed. Done. A transport belt 44, a fixing device 45, a discharge roller 46, a discharge tray 47, and the like are provided as a fixing and discharging mechanism for the sheet after the transfer. Note that an automatic document feeder (not shown) may be provided to automatically and sequentially feed a plurality of documents between the contact glass 22 and the document holder 23.

Next, a configuration example of the developing device 37 will be described with reference to FIG.

The hopper 371 stores toner. The supply roller 372 supplies toner from the hopper 371 to the tank 373. The stirring rollers 374 and 375 stir and mix the toner and the carrier in the tank 373 and frictionally charge the toner. The developing roller 376 supplies toner to the photoconductor.

Then, the frictionally charged toner is supplied to the photoconductor, and the electrostatic latent image on the photoconductor is developed with the toner. Also,
The hopper 371 can be appropriately replenished with toner.

Subsequently, a block configuration showing an example of the control system will be described with reference to FIG.

The toner density sensor 1 is provided at an appropriate position around the stirring roller 375 (see FIG. 3), detects the toner density, and outputs a voltage corresponding to the toner density to a central control unit (hereinafter referred to as CPU) 11.
Is output to Note that the voltage from the toner density sensor 1 (hereinafter, referred to as a sensor voltage) decreases as the toner density increases and increases as the toner density decreases. The operation unit 2 starts copying,
This is for setting the mode, setting the magnification, setting the number of copies, and the like. Further, the operation unit 2 has a display area in which an empty signal is received from the CPU 11 and an empty display is performed. The AD converter 3 converts an image signal from the CCD 30 into a digital signal and outputs the digital signal to the image memory 4. The image memory 4 stores the digital signal and outputs the stored content to the CPU 11.

The optical system motor 5 drives the light source of the optical mechanism L and the reflecting mirrors 26, 27, 28 and the like in accordance with a control signal from the CPU 11. The toner supply motor 6 drives the supply roller 372 in response to a control signal from the CPU 11. The toner stirring motor 7 is driven by a stirring roller 374,3 in response to a control signal from the CPU 11.
It drives 75. The paper feed roller motor 8 is connected to the CPU 11
The sheet feed roller 42 and the pair of registration rollers 43 are driven in response to a control signal from the CPU. Each of the above motors 5
Instead of 8, the driving force may be transmitted from the main motor by a clutch.

The RAM 9 and the ROM 10 store the processing program of the CPU 11, the processing contents, and a preset sensor voltage and the like. That is, the ROM 10 has a sensor voltage V _C corresponding to a toner density at a control level at which a copy operation can be performed without supplying toner, a sensor voltage V ₂ at an empty level at which a copy operation cannot be performed, and a ROM between the control level and the empty level. made copy operation there to store each time the predetermined time t _X only sensor voltage V ₁ of the quiescent level to pause _{(V C <V 1 <V} 2) and the paper said predetermined time determined by size t _X ing. Further, the ROM 10 is configured to previously store a sensor voltage V ₃ (V ₂ = V ₃ may be used) for performing an empty display.

The CPU 11 controls the motors 5 to 8 (ON / OFF of the clutches when a clutch is provided instead of the motors 5 to 8), and performs a scaling process on the image signal read by the CCD 30 as necessary. Then, the laser generator 31 irradiates a laser beam corresponding to the image signal after the scaling process. Further, CPU 11 along with (or when the clutch is provided the clutch instead of the motor 7) for driving the stirring roller 374 and 375 outputs a control signal to the toner stirring motor 7, the sensor voltage is equal to or higher than the voltage V _C A control signal is output to the toner supply motor 6 (or a clutch when a clutch is provided instead of the motor 6) to drive the supply roller 372. Furthermore, C
The PU 11 has a function of determining whether the sensor voltage is equal to or higher than the voltage V ₁ , a function of suspending the copy operation for the time t _{X at the} end of each copy operation in continuous copying, and the operation unit 2.
The Maniyuaru instruction from, or when automatic sensor voltage when the multi-consumption mode is set will be voltages V ₁ or more based on the later-described pre-scan, a識能giving pause time as described above I have. Further, CPU 11 detects the paper size has a function of setting the t _X time by the paper size detecting sensor (not shown) provided around the sheet feed cassette 41.

Next, a first embodiment of the toner density control according to the above configuration will be described with reference to the flowchart of FIG.

First, the number of copies is set by the operation unit 2 (or a plurality of documents are set in the automatic document feeder).
When copying (recording) is started, the sensor voltage V in step S ₁ is whether the following voltage V _C, namely whether the optimum toner density or higher is determined. If the sensor voltage V is equal to or lower than the voltage V _C (YES in step S ₁ ), the toner concentration is equal to or higher than the optimum toner concentration, so that the toner replenishing motor 6 (or, if a clutch is provided instead of the motor 6, the clutch). without the toner replenishment is performed by the drive of), the copy operation is performed in step S _2. That is, after an original is read and an electrostatic latent image is formed on the photoreceptor 34, the electrostatic latent image is developed with toner by the developing device 37 and transferred to paper, and the transfer paper is fixed and discharged. . Subsequently, it is determined whether a copy of the number of copies set in step S ₃ is completed, the copy of the configuration number of sheets has been completed (YES at Step S _3), the processing of this flowchart is terminated .

On the other hand, that remains the number to be copied in step S ₃ (step S ₃ in NO), it is determined whether the sensor voltage V is less than or equal to the voltage V _C returns to step S ₁ again. Then, in Step S ₁ and the sensor voltage V is equal to or higher than the voltage V _C (NO in Step S _1), whether the sensor voltage V is voltages V ₁ or less in Step S ₄ because it is less toner concentration optimum is determined , a sensor voltage V is voltages V ₁ or less (step S ₄ YES), while performing the toner replenishment by the driving of the toner supply motor 6 (or clutch) at step S ₅ to maintain the toner concentration, in step S ₂ A copy operation is performed. Whether copy setting number of sheets in step S ₃ after this has been completed is determined, and there remain sheets to be copied (Step S ₃ NO), the flow returns to step S _1. on the other hand,
When the sensor voltage V at step S ₄ is changed to voltages V ₁ or more (NO in step S _4), the sensor voltage V is whether the voltage V ₂ or less is determined in step S _6.

Then, the sensor voltage V is a voltage V ₂ or more (NO in step S _6), the toner concentration is very low, it becomes impossible good copy, the toner empty display in the step S ₁₀ (hereinafter, referred Enputei display) is Done. Then, wait until the toner is replenished to the hopper 371 in step S _11, if it is the toner replenished (YE in Step S ₁₁
S), the copy operation is performed the process proceeds to step S _2.

On the other hand, a sensor voltage V in step S ₆ is a voltage V ₂ or less (YES in step S _6), in order to recover in a short period of time the toner density shortage, the driving of the toner supply motor 6 (or clutch) at step S ₇ , The copying operation is paused for a preset time t _X , for example, several seconds. Then, after the t _X time, the copy operation is performed at step S _8, it is determined whether the copy of the configuration number of sheets in step S ₉ is completed, (steps a copy of the configuration number of sheets has been completed in S ₉ YES), the processing of this flowchart is terminated. The toner replenishing dormant copying operation is from the time when voltages V ₁ or more is detected until when the voltage V _C is detected is performed supplementation t _X time, the voltage V _C
Supply is stopped in the following cases.

On the other hand, that remains the number to be copied in step S ₉ (NO in step S _9), it is determined whether the sensor voltage V is a voltage V ₂ or less returns to step S ₆ again. As long as the sensor voltage V is not the voltage V ₂ or more (NO in step S _6), each copy to copy the set number is completed, the copy operation is performed with t _X time pause (Step S ₆ ~ loop of step S _9).

Here it will be described with reference to FIG. 5, the operation of when the sensor voltage V according to the present invention is to voltages V ₁ or more.

First, if the sensor voltage V toner consumption is large when the continuous copying operation in time point t ₁ of the voltage V _C is started, the toner density sensor voltage V is lowered gradually rises from voltage V _C. Then, the sensor voltage V at t ₂ point exceeds the voltage V _1, is resting only copying operation t _X times for each termination 1 copies, toner replenishment is performed by the drive during this period the toner supply motor 6 (or clutch) . Thus, the t _X time, so that the sensor voltage V is decreased as shown. After this copy operation is resumed, the next copy operation is completed, it is performed toner supply again t _X time. That is, the toner replenishment t _X time of the copying operation ends each is continued until the copy of the set number is completed (step S
₆ to the loop of steps S _9), the toner concentration gradually rises, the sensor voltage V at t ₃ time becomes the voltage V _C. And
When the toner density becomes equal to or higher than the control level, the toner supply is stopped, and when the toner density becomes lower than the control level, the toner supply is started again.

On the other hand, during the processing of the loop of steps S ₆ ~ step S _9, for example, made toner running low in the hopper 371 at t ₄ time, since the toner density decreases gradually reduces the amount of toner supplied to the tank 373, sensor voltage V is gradually increased to reach the voltage V ₂ at t ₅ times. In this case, empty display is performed to wait until more toner hopper 371 is replenished (step S _10, S _11).

Further, when the toner consumption is small when the continuous copying operation is started at the time point t ₁ is, t up to ₄ time the sensor voltage V is the voltage V _C, namely remained toner concentration optimum,
As shown in two-dot chain line in FIG. 5, a hopper 371 at t ₄ time
When the toner of the inner is running low, performs a normal copying without a pause of the copy operation, this after the sensor voltage V becomes voltages V ₁ or (t ₆ time), the rest of the copy operation, at t ₇ time Upon reaching the voltage V _2, empty display is performed, it may wait without further performing the copying operation until the toner in the hopper 371 is replenished.

Further, as a second embodiment of a toner concentration control, the display level between a rest level and empty level, namely V ₁ the sensor voltage V <V ₃ set the voltage V ₃ to the <V _2, the sensor voltage V is the voltage V _{When it is 3} or more (t _{9 in} the solid line in FIG. 5).
Time, time t ₈ is a two-dot chain line), empty display is performed, it may wait until more toner hopper 371 is replenished. In this case, a decrease in the toner density due to a decrease in the amount of toner remaining in the hopper 371 and a decrease in the amount of replenished toner can be notified at an early stage.

In the above description, the toner density control device is applied to a digital copying machine. However, the present invention can be applied to an image forming device such as a printer.

Moreover, by delaying the copy start time for a predetermined time may be given time t _X one by one copy end. Further, the detection of the toner density may be performed after the copying operation is stopped, or may be performed after the copying operation is completed.

Further, means for detecting the amount of toner consumption and the amount of toner supply are provided, and when the amount of toner consumption is relatively small, the time t _X is changed to be shorter, thereby stabilizing the toner concentration (see the broken line in FIG. 5). At the same time, the time until the copy is completed may be shortened.

〔The invention's effect〕

According to the present invention, when the replenished toner concentration changes below a preset pause level, the recording operation is suspended for a preset extremely short time each time one recording is completed. Can be done simultaneously. Further, since the pause control of the recording operation is performed for each recording, the recording is performed at equal intervals even when the toner consumption is large, and an irregular operation such as a long pause during continuous recording as in the related art is performed. Can be prevented and a sense of security can be given to the user.

Also, when the toner density changes below the detection level set between the pause level and the empty level, an empty display is displayed, so that the user can be notified of the decrease in toner density at an early stage, Recording can be prevented, and deterioration of the carrier can be prevented.

Further, when the toner density falls below the detection level set between the pause level and the empty level, the recording operation is stopped, so that long-time recording at a low density before toner replenishment is performed can be prevented. Degradation can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system of the toner density control device according to the present invention, FIG. 2 is a block diagram of an image forming apparatus to which the toner density control device according to the present invention is applied, and FIG. FIG. 4 is a flow chart showing a first embodiment of the operation of the toner density control device, and FIG. 5 is a timing chart for explaining the operation of the flow chart of FIG. DESCRIPTION OF SYMBOLS 1 ... Toner density sensor, 2 ... Operation part, 11 ... Central control part (CPU), 34 ... Photoconductor, 37 ... Developing device, 371 ...
Hopper, 372 ... Supply roller, 373 ... Tank.

Continuation of the front page (72) Inventor Ryuji Ueda 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Osaka Inside Mita Kogyo Co., Ltd. (72) Inventor Yasuhiro Kawai 1-2-28 Tamazuki, Chuo-ku, Osaka-shi, Osaka Mita (56) References JP-A-1-156678 (JP, A) JP-A-62-105173 (JP, A) JP-A-63-8766 (JP, A) JP-A-1-161383 (JP, A) , A) JP-A-63-8770 (JP, A) JP-A-63-8767 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/00 370-540 G03G 15 / 00 303 G03G 13/08-13/095 G03G 15/08-15/095

Claims (3)

(57) [Claims] An image forming apparatus in which recording is performed while toner is supplied when a detected toner concentration is between a control level and an empty level, wherein a pause level is set between the control level and the empty level. Setting means; density determining means for determining whether or not the toner density is equal to or less than the pause level; recording operation suspending means for suspending the recording operation for a preset time each time one recording is completed; And a control means for driving the recording operation suspending means when the recording density does not change to the suspending level or higher. 2. A toner density control device according to claim 1, wherein a detection level setting means for setting a detection level between a rest level and an empty level, and a second step for judging whether or not the toner density is equal to or lower than the detection level. A density discriminating means, and a display means for performing an empty display when the toner density changes below the detection level. 3. The toner density control device according to claim 2, further comprising a stop means for stopping a recording operation when the toner density changes below a detection level.