JPH0467160A - Color picture forming device - Google Patents

Abstract

PURPOSE:To prevent excessive consumption of toner and scattering and mixing of toner by stopping the picture forming operations of a color picture forming device including an AC bias voltage applied across a developing device and setting the device to an initialized state by means of an emergency stop signal. CONSTITUTION:When an emergency stop signal is inputted from an emergency stop key, a control unit 13 stops image exposing and developing sleeves 34 and the cooling fan of a lamp unit 17 and successively actuates a destaticizer 8 and cleaning device 9 so as to remove adhering toner. In addition, the unit 13 stops the application of AC and DC bias voltages across the developing sleeves 34 of actuated developing device 25, 26, and 27. Therefore, excessive consumption of the toner can be prevented, because no excessive toner is supplied to an image carrying body at the time of emergency stop and the toner can be prevented from scattering around and mixing into developing device of other colors.

Description

DETAILED DESCRIPTION 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.

Conventional Technology In color image forming apparatuses that form multicolor images, such as color copying machines, the image forming process that forms multiple monochrome images of different colors is generally repeated multiple times to obtain the desired multicolor image. It has become.

For example, in color copying machines that use electrophotography,
Separate the original into three colors and repeat the image forming process of [original exposure - charging - image exposure - development - transfer - cleaning] three times, or repeat the image forming process four times, including creating a black image, and transfer. It reproduces the color image of the original on paper. In addition, without having to transfer each time, [Original exposure - Charged image exposure -
A method in which multiple image forming units are arranged in series and each unit is A method is used in which a transfer paper is moved while sequentially forming images, and monochrome images are superimposed to obtain a multicolor image.

In all of these image forming apparatuses, multiple image forming processes are incorporated as a series of operations until one completed image is obtained, and once the image forming operation starts partially, it operates continuously until the image is completed. It was like that.

In this way, conventional image forming apparatuses operate as a series of processes from the start of the apparatus to the completion of the image, so for example, if an error in the document or operating condition settings of the apparatus is noticed immediately after the apparatus starts, it is possible to immediately stop the apparatus. Even if an attempt is made to do so, the device does not stop until all imaging processes are completed and continues to operate.

Therefore, during this time, unnecessary waiting time and wasteful consumption of toner transfer paper occur, which often results in a considerable drop in efficiency, especially when a large number of copies are to be made.

Therefore, in order to eliminate this waste of time and materials,
A color image forming apparatus has been proposed in which an emergency stop signal input at any time stops the image forming operation even if the image formation is not completed (Japanese Unexamined Patent Application Publication No. 62
-157068).

Problems to be Solved by the Invention In the case of the color image forming apparatus described above, charging etc. are stopped in synchronization with the emergency stop, but during the image forming process of that color, the developer conveyance of the developing means continues. There is.

Therefore, there is a high possibility that excess toner will be consumed due to the potential of the photoreceptor, and the toner may scatter or the toner on the photoreceptor may mix into the developing device of another color.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a color image forming apparatus that can prevent unnecessary toner consumption and toner scattering and mixing when unnecessary copying is stopped.

Means for Solving the Problems A color image forming apparatus according to the present invention includes an image bearing member, a latent image forming means for forming a latent image on the image bearing member, and a developing device including a plurality of developing units storing toners of different colors. A color image forming apparatus comprising a control means for controlling a color image forming process in which a color toner image is formed by separately operating a plurality of developing devices of the developing means, a transferring means, a cleaning means, a transfer paper supplying means, and the developing means. 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 at least the alternating current bias voltage of the developing unit to be turned on even if the color image forming process is not completed. The control means is characterized in that the control means has a function of performing emergency stop control to stop image forming operations including image forming operations and return the apparatus to an initial state.

Operation During an emergency stop, the alternating current bias voltage of the developing device is stopped, so excess toner is not supplied to the image 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 parts of a digital color copying machine, and FIG. 2 schematically shows the electrical structure of the main parts.

As shown in FIG. 1, the copying machine is equipped with a photoreceptor drum (1) as an image carrier, and around the photoreceptor drum (1) there is a charger (2),
A writing unit/soto (3), a developing unit (4), a paper feed unit (5), a transfer/separation unit (6), a fixing device (7), a static eliminator (8), a cleaning device (9), etc. are provided. ing.

Further, a document reading unit (11) is provided below a document table (10) provided above these. Further, as shown in FIG. 2, the copying machine is equipped with an operation knob (12) for setting operating conditions, etc., and a control unit (13) for controlling the entire machine.

The photosensitive drum (1) is driven by a main motor (14). Further, the entire circumferential surface of the photoreceptor drum (1) is charged by a charger (2), and as will be described later, images of a plurality of colors are superimposed on this.

The document reading unit (11) constitutes a document reading means for exposing and scanning a document placed on the document table (10) using a moving optical system, and includes a document scanning lamp unit (1B) having an exposure lamp (1B). 17), movable mirror unit (18), lens (19), light splitting prism (
20) and an image sensor (21) (CCD). Although not shown, the lamp unit (17
) is equipped with a cooling fan. The original is scanned by the lamp unit (17), and the image is reflected by the mirror of the lamp unit (17) and the movable mirror unit (18), and is sent to the lens (19) and the photoresolving prism (
20), the light is separated into multiple colors, and an image is formed on an image sensor (21) that receives each color image. The received color images are photoelectrically converted into electrical signals corresponding to each color image. After this is AD converted by a processing section, it is further processed into an image signal for recording by an image processing section (as shown).

The writing unit (3) is the reading unit (11)
The latent image forming means forms an electrostatic latent image by writing an image signal from an image processing section arranged in the photoreceptor drum (1) one by one for each recording color, and a semiconductor laser ( (as shown), a polygon motor (22), a polygon mirror (23), a fixed mirror (24), and the like.

The image sensor (
21) and a polygon mirror (23) where a laser beam generated by a semiconductor laser is rotated by a polygon motor 22) based on image signals corresponding to recording colors of yellow, magenta, and cyan sent from an image processing unit. )
Image exposure is then performed via a fixed mirror (24) onto the uniformly charged peripheral surface of the photoreceptor drum (1) to form an electrostatic latent image.

The developing unit (4) constitutes a developing unit that develops the latent image on the photoreceptor drum (1) into a toner image, and has a plurality of, for example, three developing units containing developers containing toners of different colors. It is equipped with containers (25), (26), and (27). The first developing device (25) stores a developer containing yellow toner, the second developing device (26) stores a developer containing magenta toner, and the third developing device (27) stores a developer containing cyan toner. These developing devices (25), (26), and (27) are individually operated one by one to develop the electrostatic latent image on the photoreceptor drum (1) to form a toner image. Note that while one developing device (25) <26) (27) is operating, the developer layers of the other developing devices (25) (2B) (27) are stationary apart from the photoreceptor drum (1). and is in an inactive state. In addition, these developing devices <25) (2B)
In (27), a two-component non-contact development method is preferably used.

The paper feed unit (5) constitutes a transfer paper supply unit that supplies transfer paper to the photoreceptor drum (1), and includes a paper feed cassette (28), a paper feed roller (29), and the like.

The transfer/separation unit (6) constitutes a transfer means for transferring the toner image formed on the photoreceptor drum (1) onto transfer paper, and includes a transfer device (30), a separator (31), etc. There is.

The cleaning device (9) constitutes a cleaning device that cleans the peripheral surface of the photoreceptor 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 operating condition setting keys, various indicators, and the like.

The control unit (13) constitutes a control means for controlling each part of the copying machine to control the color image forming process, and includes a microcomputer (path shown). The photosensitive drum (1), charger (2), reading unit (11), writing unit (3), developing unit (4), paper feeding unit (5), transfer/separation unit) ([i ), fixing device (7), static eliminator (8), cleaning device (9), etc. are sequentially controlled by a program stored in the memory of the microcomputer of the control unit (13).

FIG. 3 shows an example of the developing device (25).

This developing device (25) itself is well known, and the case (
32), the magnet roller (33) (in this figure, the N-S magnetic poles are 11 poles), the developing sleeve (34)
, a layer thickness regulating member (35), a supply roller (3B), an agitation partition plate (37), a first agitation member (38), and a second agitation member (39). An ear cutting blade (40) may be provided below the developing sleeve (34) within the case (32). The same applies to the other developing devices (2B) (27).

In the case of color copying, the charging device (2) charges the photosensitive drum (1), the reading unit (11) exposes and scans the document, the writing unit (3) forms a latent image by image exposure, and the developing device (25) ) (2G) (27) is repeated three times, thereby
A multicolor toner image, which is a composite of monochrome toner images, is formed on the photoreceptor drum (1).

In the first image creation process, the reading unit (
11), the document is exposed for recording with, for example, yellow toner, and an image signal corresponding to the yellow toner recording is output from the image processing section to the writing unit (3). The photoreceptor drum (1) is charged by a charger (2), and based on the image signal for recording yellow toner, yellow toner is applied onto the photoreceptor drum (1) by image exposure of the writing unit (3). An electrostatic latent image is formed for recording. This electrostatic latent image for yellow toner recording is produced by a first developing device (25) having yellow toner.
The toner image is developed by the operation of , and a yellow toner image is formed.

Similarly, in the second image forming process, the reading unit (11) exposes the document for recording with magenta toner, for example, and an image signal corresponding to magenta toner recording is transmitted from the image processing section to the writing unit (11).
3), and based on this image signal for magenta toner recording, an electrostatic latent image for magenta toner recording is formed on the photoreceptor drum (1) by image exposure of the writing unit (3>). This electrostatic latent image for magenta toner recording is produced by a second developing device (26) containing magenta toner.
), and a magenta toner image is further superimposed on the photosensitive drum (1) having the yellow toner image.

Furthermore, similarly, in the third image forming process, the document is exposed for recording with cyan toner, for example, and an image signal corresponding to cyan toner recording is output from the image processing section to the writing unit (3). Based on this 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 writing unit (3).

This electrostatic latent image for cyan toner recording is developed by the operation of the third developing device (27) having cyan toner, and the photoreceptor drum (27) having yellow and magenta toner images is developed.
1) A cyan toner image is further formed in an overlapping manner.

As a result, multicolor toner images of yellow, magenta, and cyan are formed on the photoreceptor drum (1).

When a multicolor toner image is formed through three image forming processes in this way, the transfer paper is supplied from the paper feed cassette (28) to the photosensitive drum (1), and the transfer/separation unit (
6) is activated and the toner image is transferred to the transfer paper. Then, the transfer paper onto which the toner image has been transferred is fixed by a fixing device 7), and a completed copy is discharged onto a paper discharge tray (path shown).

During the above three image forming processes, the cleaning device (9
) has moved away from the photoreceptor drum (1) and has stopped operating. When the transfer is completed, the cleaning device (9) is activated to remove the residual toner on the photoreceptor drum (1), and when the entire photoreceptor drum (1) has been cleaned, the photoreceptor drum (1) is removed. , and stop to complete one imaging cycle.

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

In Figure 4, the solid lines indicate the processes during normal operation, and the periods in the upper row of each line indicate that the process is in operation, and the periods in the lower row indicate that the process is in a dormant state. .

When a start signal is input at time to, the photosensitive drum (1
) starts rotating, and at the same time, the charger (2) operates to charge the entire surface of the photoreceptor drum <1>. Photosensitive drum (1
) rotates and reaches near the beginning of the charged part or the writing unit (3), the reading unit (11
) is activated to start exposing the document for yellow toner recording, and at the same time, image exposure of the writing unit (3) is activated to start forming a latent image for yellow toner recording (time tl). When the vicinity of the beginning 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 operated to start development using yellow toner (at time t
2) It varies depending on the record length, but for the maximum length record,
This continues while the photosensitive drum (1) rotates approximately once.

When the photoreceptor drum (1) rotates and the vicinity of the leading edge of the yellow toner image reaches the position of the charger (2) again, the photoreceptor drum (1) is charged again and the document is exposed and imaged for magenta toner recording. Exposure is started (time t3). Furthermore, when the vicinity of the beginning of the magenta latent image on the photosensitive drum (1) reaches the position of the second developing device (26), the second developing device (26)
Then, the developing sleeve (34) is operated to start developing with magenta toner (time t4). On this occasion,
The magenta toner image is formed overlapping the already formed yellow toner image.

Similarly, at time t5, exposure of the original document and image exposure for cyan toner recording is started, and furthermore, development with cyan toner is started from time t6, but when the vicinity of the beginning reaches the transfer/separation unit (6) ( At time t7), the transfer/separation unit (6) operates, and the photosensitive drum (1)
Transfer to the transferred transfer paper is started in synchronization with the upper toner image, and this continues until the photosensitive drum (1) rotates approximately once and transfer and separation of the entire image is completed.

When the leading edge of the photosensitive drum (1) that has been transferred and separated reaches the position of the static eliminator (8) (time t8), the static eliminator (
8) further reaches the position of the cleaning device (9) (time t9), each of the cleaning devices <9) is activated and starts cleaning the surface of the photoreceptor drum (1).

When the photoreceptor drum (1) completes cleaning of the entire surface by making approximately one more rotation and returns to the position shown in FIG. 1, the photoreceptor drum (1) stops. 17. One cycle of multicolor image formation is completed (time t 10).

During this time, charging, document exposure, and image exposure are sequentially stopped at time tll when the third cyan image forming process is completed, development at time t12, transfer at time t13, charge removal at time t14, and cleaning at time t15. At the time tlo when the photosensitive drum (1) stops, everything returns to its initial state and is ready for the next start. The interval between each of the above points is
This corresponds to the distance above the photoreceptor drum (1) of each device.

In addition, in Fig. 4, arrows 1 to 4 indicate the direction of the photoconductor tram (
1) indicates the point in time when the photosensitive drum rotates once and returns to the starting position.From this, one cycle can be completed with four rotations of the photosensitive drum.

Next, the operation of the above-mentioned copying machine during an emergency stop will be explained.

For example, if an emergency stop signal is input from the emergency stop key at time T1 when document exposure for yellow toner recording, image exposure for yellow toner recording, and yellow toner development are in progress after startup at time t1, the control The unit (13) performs the emergency stop operation shown in dotted lines in FIG. 4 according to a predetermined program. That is, at the same time as the stop signal is input, charging, document exposure by scanning the exposure lamp (1B), image exposure, cooling fan of the developing sleeve (34) and lamp unit (17) are stopped, and the front end of the developed yellow toner image is stopped. At time T2 when the static eliminator (8) reaches a position opposite to the static eliminator (8), the static eliminator (8) and then the cleaning device (9) are activated (time T3) to start removing the toner that has already adhered to the photoconductor. The drum 1) rotates by the required length, completes cleaning, returns to the starting position, and stops at time T4, making it possible to restart. Note that the static eliminator (8) and the cleaning device (9) stop at time points T5 and T6 when static elimination and cleaning are completed, respectively.

The ear cutting blade (40) of the developing device (25) (26> (27)) is attached to the developing sleeve (
The blade (40) is switched to a non-operating state (developer supply state) in which it is away from the developing sleeve (34) and an operating state (ear-cutting state) in which it is in contact with the developing sleeve (34) as shown by the solid line. When the developing sleeve (34) rotates, the developer is supplied to the photoreceptor drum (1).

When the blade (40) is switched to the operating state, even if the developing sleeve (34>) rotates, the developer on the surface of the developing sleeve (34) is cut and removed by the blade (40), so that it is not applied to the photoreceptor drum (1). Developer is no longer supplied.Developer (
25) When (2B) (27) is equipped with such a panicle cutting blade (40), in an emergency stop, instead of stopping the developing sleeve (34), it cuts the panicles,
Toner supply can be stopped. In this case, during normal operation, the ear cutting blade (40) is kept inactive as shown by the solid line in FIG. 3, and activated as shown by the broken line in the figure at the same time as the emergency stop signal is input. In this way, during normal operation, developer is supplied to the photoreceptor drum (1) by the rotation of the sleeve (34), and at the same time as the emergency stop signal, the cutting is performed and the developing sleeve (34) rotates. The developer is no longer supplied to the photoreceptor drum (1). Of course, the developing sleeve (34) may be stopped after the ear cutting is performed.

In the above copying machine, there is also a developing device (25) in an operating state.
(2B) An AC bias voltage and a DC bias voltage are applied to the developing sleeve (34) in (27). As described below, at least the application of the AC bias voltage is stopped at the same time as the emergency stop signal is input.

FIG. 5 shows an example of a bias voltage application device for the developing device (25) in the case of regular development.

This device (47) includes an AC power source (41) and a DC power source (4
2) is connected in series with the first terminal (AI), the DC power supply (
43) is connected to the second terminal (A2) and the third terminal (
float terminal) (A3), and a developing device (25
) is adapted to be connected to one of these terminals by switching. Other developing devices (2
6) A similar bias voltage application device is also provided in (27). In this case, when the developing device is operating normally,
The developing device (25) (26) (27) is connected to the first terminal (A1
), and at the same time as the emergency stop signal is input manually, it is switched to the second terminal (A2) in the same way as when the developing device is not operating in normal operation. Therefore, during normal operation of the developing device, AC bias voltage and DC bias voltage are applied, but at the same time as the emergency stop signal is input, the application of AC bias voltage is stopped and only DC bias voltage continues to be applied. .

In this case, at the same time as the emergency stop signal is input, the third terminal A3
), the developing sleeve (34) may be placed in a floating state, and the application of the AC bias voltage may be stopped.

FIG. 6 shows an example of a bias voltage application device for the developing device (25) in the case of reversal development.

This device (48) consists of an AC power source (44) and a DC power source (44).
5) is connected in series to the first terminal (Bl), resistor 46
) is connected to a second @ terminal (B2) and a third terminal (float terminal) (B3), and the developing sleeve (34) of the developing device (25) can be connected by switching to one of these terminals. It is now possible to do so. Other developing devices (26)
(27) is also provided with a similar bias voltage application device. In this case, when the developing device is in normal operation, the developing device (25) (2B) (27) is connected to the first terminal (Bl), and at the same time the emergency stop signal is input, the same as when the developing device is not operating in normal operation. is switched to the second terminal (B2).

Therefore, during normal operation of the developing device, AC bias voltage and DC bias voltage are applied as shown by the solid line in Figure 4, but at the same time as the emergency stop signal is input, the developing sleeve (34) becomes grounded. , application of both the AC bias voltage and the DC bias voltage is stopped, and no bias voltage is applied. In this case as well, at the same time as the emergency stop signal is input, the terminal is switched to the third terminal (B3) and the developing sleeve (34
) may be floated and the application of the AC bias voltage may be stopped.

At the same time as the emergency stop signal is input, at least the developer (25)
(213) Since the application of the AC bias voltage in (27) is stopped, no developer is supplied to the photosensitive drum (1) from then on. Therefore, consumption of excess toner is prevented, toner is prevented from scattering, and photoconductor drum (1
) The toner on the developer is a different color (25) (2B) (
27).

In the above embodiment, at the same time as the emergency stop signal is input, the developing sleeve (34) of the developing device (25) (26) (27)
The supply of developer to the photoreceptor drum 1) is also stopped by stopping the cutting blade (40) or cutting the ears by the ear cutting blade (40). In this way, it is preferable to stop or cut the developing sleeve (34) at the same time as the emergency stop signal is input, but it is not necessary.
The developing sleeve (34) of (27) may not be stopped, but the developing sleeves (34) of the next and subsequent developing devices (25) (2Ei) (27) may be stopped.

In the above-mentioned copier, it is possible to input an emergency stop signal at any point in the process of forming a multicolor image to immediately stop the device, thereby reducing wasteful consumption of materials such as toner and transfer paper, and work time. can be significantly reduced.

The present invention can also be applied to color image forming apparatuses other than digital color copying machines as described above.

For example, the present invention can be similarly applied to a transfer drum type analog color copying machine as shown in Japanese Patent Application Laid-Open No. 2-13977.

Effects of the Invention According to the color image forming apparatus of the present invention, as described above, excess toner is not supplied to the image carrier at the time of emergency stop, and therefore consumption of excess toner is prevented and toner is There is no possibility of scattering or toner on the image carrier getting mixed into developing devices of other colors.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view of the main parts of a digital color copying machine showing an embodiment of the present invention, FIG. 2 is a block diagram of the main parts of the same copying machine, and FIG. 3 is a portion of the developing unit shown in FIG. 1. 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 the bias voltage application device of the developing unit. FIG. 6 is an electric circuit diagram showing a modification of the bias voltage applying device of the developing device. (1)...Photosensitive 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) (2Ei) (27)...Developer, (40)...Ear cutting blade. Figure 2 above

Claims (4)

[Claims] (1) An image bearing member, a latent image forming means for forming a latent image on the image bearing member, a developing means having a plurality of developing devices containing toner of different colors, a transfer means, a cleaning means, a transfer paper supply means, and A color image forming apparatus comprising a control means for controlling a color image forming step in which a plurality of developing devices of the developing means are individually operated to form a color toner image, wherein at least a part of the color image forming step is performed. After the start, an emergency stop signal generated by an external operation causes the image forming operation including at least the AC bias voltage of the developing unit to be stopped even if the color image forming process is not completed, and the apparatus is returned to the initial state. A color image forming apparatus, wherein the control means has a function of performing emergency stop control. (2) When an emergency stop signal is input, the application of the AC bias voltage to the developing device that was previously used is stopped, and only the DC bias voltage continues to be applied. ) color image forming device. (3) The color image forming apparatus according to claim 1, wherein the developing sleeve of the developing unit is brought into a grounded state or a floating state when an emergency stop signal is input. (4) Claim (1) characterized in that, when an emergency stop signal is input, a cutting blade of a developing unit is brought into contact with a developing sleeve to simultaneously perform a cutting process in which developer on the surface of the developing sleeve is removed. color image forming device.