JP2916649B2 - Color image forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus, such as a color copying machine or a color printer, which completes one image by repeating an image forming process a plurality of times.

2. Description of the Related Art In a color image forming apparatus for forming a multicolor image such as a color copying machine, an image forming process for forming a plurality of single color images of different colors is generally repeated a plurality of times to obtain a required multicolor image. Has become.

For example, in a color copying machine using electrophotography,
The original is separated into three colors, and the image forming process of [original exposure-charging-image exposure-development-transfer-cleaning] is repeated three times, or the image forming process of adding a black image is repeated four times to transfer. The color image of the original is reproduced on paper. In addition, the transfer is not performed each time, and the process of “document exposure-charging-image exposure-development” is repeated for each color, and a multicolor toner image is formed on the photoconductor (image carrier), and then the transfer is performed. A method of obtaining an image, a method of arranging a plurality of image forming units in series, moving a transfer sheet while sequentially forming an image in each unit, and superimposing a single color image to obtain a multicolor image are performed.

In each of these image forming apparatuses, a plurality of image forming processes for obtaining one completed image are incorporated as a series of operations, and once the image forming operation is started, the image forming apparatus operates continuously until the image is completed. Had become.

As described above, the conventional image forming apparatus operates as a series of operations from the start of the apparatus to the completion of the image. Therefore, for example, immediately after the apparatus is started, an error such as a setting of an original or an operating condition of the apparatus is noticed. In such a case, the apparatus does not stop until all the image forming processes are completed, and the operation is continued. Therefore, during this time, wasteful waiting time, wasteful consumption of toner, transfer paper, and the like occur, and especially when a large number of copies are made, the efficiency is often not negligible.

Therefore, in order to eliminate such waste of time and materials, a color image forming apparatus in which an image forming operation is stopped even when image formation is not completed by an emergency stop signal input at an arbitrary time. Has been proposed (Japanese Unexamined Patent Publication
62-157068).

In the above-described color image forming apparatus, when the emergency stop signal is input, the developing operation for the next color is stopped after the current color developing operation is completed, and the photosensitive drum is rotated by one rotation. After the entire surface is cleaned as described above, the photosensitive drum is stopped.

When an emergency stop signal is input, charging and the like are stopped in synchronization with the input, but until the color developing operation is completed, the formation of the toner image is continued. Supply of toner is continuing. Therefore, there is a high possibility that excess toner is consumed due to the potential of the photoconductor, and the toner may be scattered or the toner on the photoconductor may be mixed into a developing device of another color.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image forming apparatus which solves the above-mentioned problem and can prevent unnecessary toner consumption, toner scattering and mixing when stopping unnecessary copying.

Means for Solving the Problems A color image forming apparatus according to the present invention includes a developing device having an image carrier, a latent image forming device for forming a latent image on the image carrier, and a plurality of developing devices containing toners of different colors from each other. Image forming apparatus for controlling a color image forming step of forming a color toner image by operating a plurality of developing units of a developing unit, a transfer unit, a cleaning unit, a transfer paper supply unit, and the developing unit. In the apparatus, after at least a part of the color image forming process is started, an emergency stop signal generated by an external operation causes the cutting blade of the developing device to immediately contact the developing sleeve to remove the developer on the surface. The function to perform the emergency stop control to reset the device to the initial state after the removal of the ears and the stopping of the developing sleeve of the developing device are provided. Control means is characterized in that a.

When the emergency stop signal is input, the cutting blade of the developing unit is immediately brought into contact with the developing sleeve to perform the cutting to remove the developer on the surface, and the developing sleeve of the developing unit is stopped. It is not supplied to the carrier.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the mechanical structure of the main part of the digital color copying machine, and FIG. 2 schematically shows the electric structure of the main part.

As shown in FIG. 1, the copying machine includes a photosensitive drum (1) as an image carrier, and a charger (2), a writing unit (3), a developing unit (4), and a paper feeder are provided around the photosensitive drum (1). A unit (5), a transfer / separation unit (6), a fixing device (7), a static eliminator (8), a cleaning device (9), and the like are provided. A document reading unit (11) is provided below a document table (10) provided above these. Further, as shown in FIG. 2, the copying machine includes an operation panel (12) for setting operating conditions and the like, a control unit (13) for controlling the whole, and the like.

The photoconductor drum (1) is driven by a main motor (14). Further, the entire peripheral surface of the photosensitive drum (1) is charged by the charger (2), and as described later, a plurality of color images are formed thereon.

The document reading unit (11) constitutes a document reading means for reading a document placed on a document table (10) by exposing and scanning with a moving optical system, and a document scanning lamp unit having an exposure lamp (16). 17), a movable mirror unit (18), a lens (19), a light resolving prism (20), and an image sensor (21) (CCD). Although not shown, the lamp unit (17) is provided with a cooling fan. The original is scanned by the lamp unit (17), and the image is reflected by the mirrors of the lamp unit (17) and the movable mirror unit (18) to form a lens (1).
9) and sent to the photo-resolving prism (20) to form an image on an image sensor (21) that splits the light into a plurality of colors and receives each color image. The received color image is photoelectrically converted into an electric signal corresponding to each color image. In the processing section
After AD conversion, the image signal is further processed into an image signal for recording by an image processing unit (not shown).

Write unit (3) is read unit (11)
Latent image forming means for forming an electrostatic latent image by writing an image signal from the image processing unit disposed in the photoconductor drum (1) for each recording color one by one, and comprises a semiconductor laser ( (Not shown), a polygon motor (22), a polygon mirror (23), a fixed mirror (24), and the like. The image sensor (21) of the reading unit (11) and the yellow, magenta, and
Based on the image signal corresponding to the cyan recording color, the laser beam generated by the semiconductor laser is
An image is exposed on the peripheral surface of the photosensitive drum (1) uniformly charged via the polygon mirror (23) and the fixed mirror (24) rotated in 2), and an electrostatic latent image is formed.

The developing unit (4) constitutes a developing unit that develops a latent image on the photosensitive drum (1) into a toner image, and a plurality of, for example, three developing units containing developers containing toners of different colors. Containers (25), (26) and (27) are provided. The first developing device (25) has a yellow toner and the second developing device (26)
Contains a magenta toner, and the third developing device (27) contains a developer containing a cyan toner. These developing units (25), (26) and (27) are operated individually one by one, and develop the electrostatic latent image on the photosensitive drum (1) to form a toner image. In addition, one developing device (25) (26) (2
While 7) is in operation, other developing units (25) (26) (27)
The developer layer is not moving away from the photosensitive drum (1) and is in a non-operating state. In these developing units (25), (26) and (27), a two-component non-contact developing method is suitably used.

The paper supply unit (5) transfers the transfer paper to the photosensitive drum (1).
And a paper feed unit (28), a paper feed roller (29), and the like.

The transfer / separation unit (6) constitutes transfer means for transferring the toner image formed on the photosensitive drum (1) to transfer paper, and includes a transfer unit (30) and a separator (31). I have.

The cleaning device (9) constitutes cleaning means for cleaning the peripheral surface of the photosensitive drum (1) by, for example, a blade cleaning method or a fur brush cleaning method.

Although not shown, the operation panel (12) is provided with a start key, an emergency stop key, various operation condition setting keys, various indicators, and the like.

The control unit (13) constitutes control means for controlling each part of the copying machine to control the color image forming process, and includes a microcomputer (not shown).
The photosensitive drum (1), the charger (2), the reading unit (11), the writing unit (3), the developing unit (4), the paper feeding unit (5), the transfer / separation unit (6), The fixing device (7), the static eliminator (8), the cleaning device (9), and the like are sequence-controlled by a program stored in a memory of a microcomputer of the control unit (13).

FIG. 3 shows an example of the developing device (25). The developing device (25) itself is known, and a magnet roller (33) (in this case, the number of N and S magnetic poles is 11), a developing sleeve (34), a layer A thickness regulating member (35), a supply roller (36), a stirring partition (37), a first stirring member (38), and a second stirring member (39) are provided.
An ear cutting blade (40) is provided below the developing sleeve (34) in the case (32). Other developing units (26) (2
7) is similar to this.

In the case of color copying, charging of the photosensitive drum (1) by the charger (2), exposure scanning of the original by the reading unit (11), latent image formation by image exposure of the writing unit (3), and development by the developing unit (25) The image forming process including the development by (26) and (27) is repeated three times, thereby forming a multicolor toner image obtained by synthesizing a single color toner image on the photosensitive drum (1).

In the first image forming process, the reading unit (11) performs document exposure for recording using, for example, yellow toner, and an image signal corresponding to yellow toner recording is output from the image processing unit to the writing unit (3). You. The photoconductor drum (1) is charged by a charger (2). Based on the image signal for yellow toner recording, the yellow toner is exposed on the photoconductor drum (1) by image exposure of a writing unit (3). An electrostatic latent image for recording is formed. The electrostatic latent image for yellow toner recording is developed by the image forming of the first developing device (25) having yellow toner, and a yellow toner image is formed.

Similarly, in the second image forming process, the reading unit (11) performs document exposure for recording using, for example, magenta toner, and an image signal corresponding to magenta toner recording is sent from the image processing unit to the writing unit (3). The electrostatic latent image for magenta toner recording is formed on the photosensitive drum (1) by image exposure of the writing unit (3) based on the image signal for magenta toner recording. The electrostatic latent image for magenta toner recording is developed by the operation of the second developing device (26) having magenta toner, and a magenta toner image is further superimposed on the photosensitive drum (1) having a yellow toner image. Formed.

Furthermore, similarly, in the third imaging process,
For example, document exposure for recording with cyan toner is performed, an image signal corresponding to cyan toner recording is output from the image processing unit to the writing unit (3), and writing is performed based on the image signal for cyan toner recording. An electrostatic latent image for cyan toner recording is formed on the photosensitive drum (1) by image exposure of the unit (3). The electrostatic latent image for recording the cyan toner is developed by the operation of the third developing device (27) having the cyan toner, and a cyan toner image is further formed on the photosensitive drum (1) having the yellow and magenta toner images. They are formed in layers. And
Thus, a multicolor toner image of yellow, magenta, and cyan is formed on the photosensitive drum (1).

When a multicolor toner image is formed by the three image forming processes in this manner, transfer paper is supplied from the paper supply unit (28) to the photosensitive drum (1), and the transfer / separation unit (6) is In operation, the toner image is transferred to the transfer paper. Then, the transfer paper to which the toner image has been transferred is fixed by a fixing device (7) to be a completed copy, and a discharge tray (not shown)
Is discharged.

During the three image forming processes, the cleaning device (9) is separated from the photosensitive drum (1) and stops operating. When the transfer is completed, the cleaning device (9) operates to remove residual toner on the photosensitive drum (1),
When cleaning of the entire photosensitive drum (1) is completed, the photosensitive drum (1) is stopped, and one image forming cycle is completed.

FIG. 4 is a time chart showing the progress of the image forming process in the above copying machine.

In FIG. 4, the solid line indicates a process during normal operation, and each line indicates that the process is in an operating state during an upper period, and is in a rest state during a lower period. .

When the activation signal at time t ₀ is input, the photosensitive drum (1) starts rotating, at the same time, the charger (2) causes the entire charge the photosensitive drum operated (1). When the photosensitive drum (1) rotates and the vicinity of the head of the charged portion reaches the position of the writing unit (3), the reading unit (11) operates to start document exposure for yellow toner recording. At the same time, the image exposure of the writing unit (3) is activated to start forming a latent image for yellow toner recording (time t1). When the vicinity of the head of the yellow latent image on the photosensitive drum (1) reaches the position of the first developing device (25),
The first developing device (25) and its developing sleeve (34) are activated to start developing with yellow toner (time t2),
Although it depends on the recording length, in the case of the recording of the maximum length, this continues while the photosensitive drum (1) makes substantially one rotation.

When the photosensitive drum (1) rotates and the vicinity of the head of the yellow toner image reaches the position of the charger (2) again, the photosensitive drum (1) is charged again, and development exposure and image formation for magenta toner recording are performed. Exposure is started (time t3). Further, when the vicinity of the head of the magenta latent image on the photosensitive drum (1) reaches the position of the second developing device (26), the second developing device (26) and its developing sleeve (34) are operated, and the magenta toner Is started (time t4). At this time, the magenta toner image is formed so as to overlap the already formed yellow toner image.

Similarly, document exposure and image exposure for cyan toner recording are started at time t5, and development with cyan toner is further started at time t6, but when the vicinity of the head reaches the transfer / separation unit (6). (Time t7), transcription
The separation unit (6) is operated, transfer to the transfer paper sent in synchronization with the toner image on the photoconductor drum (1) is started, and the photoconductor drum (1) rotates substantially once, so that the entire image is This continues until the transfer and separation have been completed.

When the leading end of the photosensitive drum (1) after the transfer and the separation reaches the position of the charge eliminator (8) (time t8), the charge eliminator (8) further reaches the position of the cleaning device (9) (time t8). t9), the cleaning devices (9) are activated to start cleaning the surface of the photosensitive drum (1).

When the photosensitive drum (1) further rotates substantially one turn to complete the entire cleaning, and returns to the position where the photosensitive drum (1) is almost started, that is, the position shown in FIG. 1, the photosensitive drum (1) stops. Then, one cycle of the multicolor image formation is completed (time t10).

During this time, charging, document exposure and image exposure are stopped for the third time, that is, at time t11 at which the cyan image forming process is completed, development is at time t12, transfer is at time t13, static elimination is at time t14, and cleaning is sequentially stopped at time t15. At time t10 when the photoconductor drum (1) stops, all the states return to the initial state, and are ready for the next start. The intervals at the respective times correspond to the distances of the respective devices on the photosensitive drum (1). In FIG. 4, arrows 1 to 4 indicate the times at which the photosensitive drum (1) makes one rotation and returns to the starting position after startup, and one cycle is completed by four rotations of the photosensitive drum. You can see that.

Next, the operation of the above copying machine at the time of an emergency stop will be described.

For example, if an emergency stop signal is input from the emergency stop key at time T1 when the document exposure for yellow toner recording, the image exposure for yellow toner recording, and the yellow toner development are in progress after starting at time t1, the control is performed. The unit (13) performs an emergency stop operation indicated by a dotted line in FIG. 4 according to a predetermined program. That is,
Simultaneously with the input of the stop signal, the charging, the exposure of the original by scanning of the exposure lamp (16), the image exposure, and the cooling fan of the lamp unit (17) are stopped, and the front end of the developed yellow toner image is cut off. At the time T2 when the discharger (8) has reached the opposite position, the discharger (8) is operated, and then the cleaning device (9) is operated (time T3) to start removing the toner that has already adhered, and (1) is rotated by the required length, the cleaning is completed, and stops at the point of time T4 when it is almost returned to the start position, and the state becomes restartable. Note that the static eliminator (8) and the cleaning device (9) stop at time points T5 and T6, respectively, when static elimination and cleaning are completed.

At the same time as the emergency stop signal is input, the developing units (25) (26) (2
7) Since the developing sleeve (34) stops,
The developer is not supplied to the photosensitive drum (1).
Therefore, consumption of excess toner is prevented, and toner is not scattered and toner on the photosensitive drum (1) is not mixed into the developing units (25), (26), and (27) of other colors. .

Developing unit (25) (26) (27) Cutting blade blade (40)
A non-operating state (developer supply state) separated from the developing sleeve (34) as shown by a chain line in FIG. 3 and an operating state (spike cutting state) in contact with the developing sleeve (34) as shown by a solid line. Is switched to When the blade (40) is switched to the non-operation state, the developer is supplied to the photosensitive drum (1) by the rotation of the developing sleeve (34). Blade (40)
Is switched to the operating state, even if the developing sleeve (34) rotates, the developer on the surface thereof is cut off by the blade (40) and removed, so that the developer is supplied to the photosensitive drum (1). Will not be. Then, simultaneously with the input of the emergency stop signal, the ear cutting is performed as follows. That is, during normal operation, as shown by the solid line in FIG.
0) is deactivated, and is activated simultaneously with the input of the emergency stop signal as indicated by the broken line in FIG. In this case, during normal operation, the developer is supplied to the photosensitive drum (1) by the rotation of the sleeve (34), and at the same time as the emergency stop signal, the ear is cut off, so that the developing sleeve (34)
The developer is no longer supplied to the photosensitive drum (1) even if is rotated. Then, after the ear cutting, the developing sleeve (34) is stopped.

When the developing unit (4) performs regular development, the application of the bias voltage of the developing device can be continued even during an emergency stop.

In both normal development and reversal development, when an AC bias voltage and a DC bias voltage are applied to the developing device,
At the time of emergency stop, at least application of the AC bias voltage can be stopped.

FIG. 5 shows an example of a bias voltage applying device for the developing device (25) in the case of regular development. This device (4
7) a first terminal (A1) to which an AC power supply (41) and a DC power supply (42) are connected in series, a second terminal (A2) to which a DC power supply (43) is connected, and a third terminal (float terminal) ) (A3), and the sleeve (34) of the developing device (25) is switched and connected to any of these terminals. Similar bias voltage applying devices are provided in other developing units (26) and (27). In this case, during normal operation of the developing device, the developing devices (25), (26) and (27) are connected to the first terminal (A
1), and is switched to the second terminal (A2) simultaneously with the input of the emergency stop signal in the same manner as when the developing device is not operating in the normal operation. For this reason, during the normal operation of the developing device, the AC bias voltage and the DC bias voltage are applied as shown by the solid line in FIG. 4, but the application of the AC bias voltage is stopped simultaneously with the input of the emergency stop signal, The application of only the DC bias voltage is continued.

FIG. 6 shows an example of a bias voltage applying device for the developing device (25) in the case of reversal development. This device (4
8) a first terminal (B1) to which an AC power supply (44) and a DC power supply (45) are connected in series, a second terminal (B2) to which a resistor (46) is connected, and a third terminal (float terminal) (B3), and the developing sleeve (34) of the developing device (25) is switched to and connected to any of these terminals. Similar bias voltage applying devices are provided in other developing units (26) and (27). In this case, during normal operation of the developing device, the developing devices (25), (26) and (27) are connected to the first terminal (B
1), and is switched to the second terminal (B2) simultaneously with the input of the emergency stop signal in the same manner as when the developing device is not operating in the normal operation. For this reason, during the normal operation of the developing device, the AC bias voltage and the DC bias voltage are applied. However, simultaneously with the input of the emergency stop signal, the application of both the AC bias voltage and the DC bias voltage is stopped, and the bias voltage is reduced. No longer applied.

In the above-described copying machine, an emergency stop signal can be input at any time during multi-color image formation, and the apparatus can be stopped quickly, and wasteful consumption of materials such as toner and transfer paper and work time can be achieved. It can be significantly reduced.

The present invention can be applied to a color image forming apparatus other than the digital color copying machine as described above. For example, the present invention can be similarly applied to a transfer drum type analog color copying machine disclosed in JP-A-2-13977.

According to the color image forming apparatus of the present invention, as described above, extra toner is not supplied to the image carrier at the time of emergency stop, and therefore, consumption of extra toner is prevented, and There is no scatter or toner on the image carrier is mixed into the developing units of other colors.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a main part of a digital color copying machine showing an embodiment of the present invention, FIG. 2 is a block diagram of a main part of the copying machine, and FIG. FIG. 4 is an enlarged longitudinal sectional view, FIG. 4 is a time chart showing an example of the operation of each part during normal operation and emergency stop of the copying machine, and FIG. 5 is an example of a bias voltage applying device of a developing device. FIG. 6 is an electric circuit diagram showing a modification of the bias voltage applying device of the developing device. (1) photoconductor drum (image carrier), (3) writing unit (latent image forming means), (4) developing unit (developing means), (5) paper feeding unit (transfer) Paper supply means), (6) transfer / separation unit (transfer means),
(9) ... cleaning device (cleaning means),
(13) Control unit (control means), (25) (26)
(27) Developing device (34) Developing sleeve (40)
… Hot cutting blade.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 21/00 384 G03G 15/08 507H (72) Inventor Takao Tsuda 1 Sakuracho, Hino City, Tokyo Konica Corporation Hino Plant (56) References JP-A-62-157068 (JP, A) JP-A-62-81674 (JP, A) JP-A-2-137869 (JP, A) JP-A-2-138571 (JP, A) Kaihei 1-296264 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 13/08-13/095 G03G 15/08-15/095 G03G 21/14 G03G 21/00 370-540

Claims (1)

(57) [Claims] 1. An image carrier, a latent image forming means for forming a latent image on the image carrier, a developing means having a plurality of developing devices containing toners of different colors, a transfer means, a cleaning means, and a transfer paper supply A color image forming apparatus for controlling a color image forming step of forming a color toner image by separately operating a plurality of developing units of the developing means. After the start of the developing unit, an emergency stop signal generated by an external operation causes the cutting blade of the developing device to immediately contact the developing sleeve to remove the developer on the surface, and perform the cutting of the developing device. A color image forming apparatus characterized in that the control means has a function of performing an emergency stop control for bringing the apparatus to an initial state after stopping the developing sleeve. Place.