JPH01314268A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent toner from being excessively replenished in initial operation and its replenishing amount from fluctuating due to peripheral temperature by counting the amount of input data and replenishing toner in response to the counted value. CONSTITUTION:The title device is provided with a photosensitive drum 12 on which an electrostatic latent image corresponding to the input data is formed, a developing device 11 developing the electrostatic latent image formed on the photosensitive drum 12 with a developer 9 containing a toner 2, a counter 35 counting the amount of input data, and a toner replenishing means replenishing the toner 2 in response to the output of the counter 35. According to the input data, the electrostatic latent image is formed on the photosensitive drum 12, and is developed with the developer 9. The toner 2 in the developer 9 is replenished in response to the amount of the input data. As a result, the toner is prevented from being excessively replenished in initial operation, or its replenishing amount from fluctuating due to peripheral temperature. In addition, an appropriate amount of toner can be replenished even if printed data has much of a black part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic apparatus typified by, for example, a copying machine, a printer, a printing device, and the like.

[Conventional technology]

Some electrophotographic apparatuses dry develop an electrostatic latent image on a photosensitive drum using a two-component developer containing a magnetic carrier and a toner. In such an electrophotographic apparatus, toner is consumed during development.

If development is performed in a state where the toner concentration in the developer has decreased, the developed concentration will decrease or the magnetic carrier will adhere to the photosensitive drum. Therefore, it is necessary to maintain the toner concentration in the developer at a predetermined level.

FIG. 2 shows the structure of a conventional developing device that maintains toner density at a constant level. In the figure, reference numeral 1 denotes a toner tank, which stores toner 2 therein. 3 is a sponge roll rotatably attached below the toner tank 2. Reference numeral 4 denotes a stirring chamber, in which a developer 9 consisting of toner and magnetic carrier is accommodated. 5 is a stirring auger, which is rotatably mounted inside the stirring chamber 4. A cylindrical magnetic sleeve 6 is rotatably supported in the stirring chamber 4, and faces the photosensitive drum 12 at a distance D (development gap). Reference numeral 7 designates a doctor member, which has a distance (doctor gap) from the sleeve 6 on the upstream side in the rotation direction of the sleeve 6 (indicated by arrow X in the figure).
They are spaced apart by d. Reference numeral 8 denotes a scraper member, which is disposed on the downstream side of the sleeve 6 in the rotational direction. Reference numeral 10 denotes a concentration sensor for detecting toner concentration, which is spaced apart from the stirring auger 5 by a distance (gap) g.

The developing device 11 is configured in this manner.

The photosensitive drum 12 is rotated in the direction shown by arrow 2 in the figure when an electrostatic latent image corresponding to input data is formed on its surface. At this time, the sleeve 6 is rotated in the direction indicated by arrow X in the figure. The developer 9 is adsorbed onto the sleeve 6, and its thickness is limited by the doctor gap d. The developer 9 adsorbed by the sleeve 6 is conveyed from the doctor gap d toward the development gap D. As a result, the photosensitive drum 12 receives the magnetic brush of the developer 9 near the developing gear D, and the electrostatic latent image on the photosensitive drum 12 is developed. The developer 9 adhering to the sleeve 6 after passing through the Tji image gap D is scraped off from the sleeve 6 by the scraper member 8 and collected into the stirring chamber 4.The collected developer 9 is passed through the stirring auger 5. As the developer rotates, it is mixed with the original developer 9.

When the developer 9 passes through the gap g as the stirring auger 5 rotates, a concentration sensor 10 detects the toner concentration in the developer. When the toner concentration falls below a predetermined reference value, the sponge roll 3 is driven to rotate, and the toner 2 is replenished from the toner tank 1 into the stirring chamber 4 . The supplied toner is stirred and mixed with the developer a by the rotation of the stirring auger 5.

In this way, the toner concentration in the developer is controlled to a constant value.

[Problem to be solved by the invention]

However, since it takes time for the density sensor 10 to generate a stable detection output after toner 2 is replenished, the density sensor 10 must be The output is now ignored. Therefore, if there are many black parts in the print data and a large amount of toner is consumed, toner may not be replenished in time. Conversely, at the beginning of the operation of the developing device 11, the toner concentration may be detected as a value lower than the actual value, and toner may be excessively replenished.

Furthermore, since the level of the detection signal from the density sensor 10 changes depending on the temperature, an appropriate toner density may not always be maintained depending on the ambient temperature.

The present invention has been developed in view of the above situation, and is designed to prevent excessive supply of toner at the beginning of operation, and to ensure that an appropriate amount of toner is always supplied regardless of the ambient temperature or even when there are many black parts in the print data. This is to replenish the amount of toner.

[Means to solve the problem]

The electrophotographic apparatus of the present invention includes a photosensitive drum on which an electrostatic latent image corresponding to input data is formed, a developing device that develops the electrostatic latent image on the photosensitive drum with a developer containing toner, and an amount of input data. The toner replenishing device includes a counter that counts the number of digits, and a toner replenishing means that replenishes toner in response to the output of the counter.

[Effect]

An electrostatic latent image is formed on the photosensitive drum in accordance with input data, and this electrostatic latent image is developed with a developer. Toner in the developer is replenished in accordance with the amount of input data.

Therefore, it is possible to prevent toner from being excessively replenished at the beginning of operation or from changing the amount of toner supplied depending on the ambient temperature. Furthermore, even if there are many black parts in the print data, it is possible to supply an appropriate amount of toner.

〔Example〕

FIG. 3 shows the structure of the developing device of the present invention.

The developing device 11 of the present invention is basically constructed in the same manner as the conventional one, except that a density sensor is not provided. Therefore, parts corresponding to those in FIG. 2 are given the same reference numerals in FIG. 3. In Figure 3,
A toner bottle 21 replenishes the toner tank 1 with toner 2. 22, 23, and 24 are a drive gear, an auger gear, and a sponge roll gear, which are meshed in sequence.

25 is a toner supply clutch. The auger gear 23 is integrally connected to the stirring auger 5.

When the former rotates, the latter also rotates.

On the other hand, the sponge roll gear 24 is connected to the sponge roll 3 via the toner replenishment clutch 25, and only when the toner replenishment clutch 25 is connected, the sponge roll gear 24 rotates along with the rotation of the sponge roll gear 24. The sponge roll 3 is also rotated.

FIG. 1 is a block diagram of an electrophotographic apparatus of the present invention using such a developing device 11. In the figure, 31 is a CPU as a control means for controlling the printing operation, and 32 is a dot data processing device that processes input data supplied from a host device, a storage device, etc. (not shown). The dot data processing device 32 outputs the data top pulse, data and sample clock to the light emitting member 33, and the light emitting member 33 irradiates the photosensitive drum 12 with predetermined light in response to these input signals to form an electrostatic latent image. Let it form. 34 is an AND circuit that calculates the AND of data and the sample clock, and 35 is a counter that counts the output of the AND circuit 34. Reference numeral 36 denotes a backup power source, which maintains the count value of the counter 35 even when the electrophotographic apparatus is powered off. A motor driver 37 drives the DC motor 38. DC motor 38 rotates drive gear 22 (FIG. 3). 39 is the toner replenishment clutch 25 (Fig. 3)
This is a control circuit that controls the

Next, the operation of the electrophotographic apparatus of the present invention will be explained with reference to the timing charts of FIGS. 4 and 5.

The CPU 31 outputs a DC motor rotation clock G (FIG. 4 G) to the motor driver 37 to drive the DC motor 38. As a result, when the DC motor 38 rotates, the drive gear 22, the auger gear 23, the sponge roll gear 24
rotates sequentially. As the auger gear 23 rotates, the stirring auger 5 is rotated, and the developer 9 in the stirring chamber 4 is stirred. On the other hand, since the toner replenishment clutch 25 is currently not connected, even if the sponge roll gear 24 rotates, the sponge roll 3 does not rotate, and therefore the toner 2 is not replenished.

After the rotational speed of the DC motor 38 becomes constant, as shown in the figure -
When the blank paper is sucked to a predetermined position and becomes ready for printing, the CPU 31, which manages pages of print data, outputs an enable signal to the dot data processing device 32.

After this, the CPU 3.1 uses the dot data processing device i32.
, one dot line pulse A for one dot line
(FIG. 4A) is further output. Print data is input to the dot data processing device 32 from an external device, a storage device, etc., and is stored therein. When the dot data processing device i32 receives the dot line pulse A, it arranges print data for one dot line. When the print data has been arranged, the dot data processing device 32 sends to the light emitting member 33 a data top pulse B representing the beginning of one dot line, followed by print data C for one dot line, and a sample clock synchronized with data C. D (B, C, D in Figure 4).

The light emitting member 33 emits light in accordance with the data C, forming an electrostatic latent image on the photosensitive drum 12.

When an electrostatic latent image for one page is formed on the photosensitive drum 12 in this way, the sleeve 6 is rotated in the same manner as in the case described above. The developer 9 in the stirring chamber 4 is transported, and the electrostatic latent image on the photosensitive drum 12 is developed.

On the other hand, data C and sample clock D (Fig. 4, Fig. 5 C)
, D) are also input to the AND circuit 34.

Data C becomes H level when corresponding to a black portion (a portion that consumes toner). Therefore, the AND circuit 34 outputs the clock corresponding to the data section of the black part as the counter input signal E (FIGS. 4 and 5 E). counter 35
Since the counter counts the number of input signals E, the count value corresponds to the substantial amount of input print data (the amount of black portion), and therefore corresponds to the amount of toner consumption.

When the count value reaches a predetermined reference value set in advance, the counter 35 generates a counter output signal F (FIG. 4F) and supplies it to the CPU 31. At this time, the CPU 31 generates a toner replenishment clutch control signal H (H in FIG. 4).

The control circuit 39 connects the toner replenishment clutch 25 while the toner replenishment clutch control signal H is input. Therefore, during that time, the sponge roll 3 rotates, and the toner 2 is transferred to the stirring chamber 4.
will be replenished. The amount of toner replenished at this time approximately corresponds to the amount of toner consumed until the count value at which the counter output signal F is generated is reached. The supplied toner is stirred into the developer 9 by the stirring auger 5.

Further, when the CPU 31 receives the input of the counter output signal F, it outputs a reset signal ■ to the counter 35 to reset the count value. Thereafter, the counter 35 counts up the counter input signal E from 1 again.

Since the count value of the counter 35 is backed up by the power supply 36, it is retained even when the electrophotographic apparatus is powered off. Therefore, when the power is turned on, the count is continuously increased from the count value immediately before the power is turned off. Note that the counter 35 may also include a built-in memory such as an EEPROM for storing count values.

〔Effect of the invention〕

As described above, according to the present invention, the amount of input data is counted and toner is replenished in accordance with the count value. This prevents the amount from changing. Furthermore, even when printing a document with many black areas, the toner density is prevented from decreasing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electrophotographic apparatus according to the present invention, FIG. 2 is a sectional view of a conventional developing device, FIG. 3 is a perspective view of a developing device according to the present invention, and FIG. 4 is a block diagram of an electrophotographic apparatus according to the present invention. Timing Chart FIG. 5 is an enlarged timing chart of a portion of FIG. 4. ■... Toner tank 2... Toner 3... Sponge roll 4... Stirring chamber 5... Stirring auger 6... Magnetic sleeve 7... Doctor part 8... Scraper member 9 ...Developer 10...Concentration sensor 11...Developer 12...Photosensitive drum Patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Scope of Claims] A photosensitive drum on which an electrostatic latent image corresponding to input data is formed, a developer that develops the electrostatic latent image on the photosensitive drum with a developer containing toner, and a device that counts the amount of input data. An electrophotographic apparatus includes a counter for replenishing toner, and a toner replenishing means for replenishing toner in accordance with the output of the counter.