JP2920681B2 - 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, for forming one completed 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, an original is separated into three colors and an image forming process of [original exposure-charging-image exposure-development-transfer-cleaning] is repeated three times.
Alternatively, the image forming process is repeated four times by adding a black image to reproduce the color image of the original on the transfer paper.
Also, without performing the transfer each time, the process of [original 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, since the conventional image forming apparatus operates as a series of operations from the start of the apparatus to the completion of the image, for example, immediately after the start of the apparatus, an error such as setting of a document or an operating condition for image forming of the apparatus is noticed. Even if an attempt is made to stop the apparatus immediately, 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, the image forming operation is stopped even when the image forming is not completed by the emergency stop signal input at an arbitrary time, and returns to the initial state. (Japanese Patent Application Laid-Open No. 62-157068).

In the above-described color image forming apparatus, image formation is continued from the time when the emergency stop signal is input to the time when the apparatus is stopped in an emergency, and during this time, excess toner is consumed. Sometimes.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, to stop image formation simultaneously with the input of an emergency stop signal, to prevent consumption of extra toner, to simplify the operation after the emergency stop, and to set the operating condition again. An object of the present invention is to provide a color image forming apparatus that is less likely to cause an error.

Means for Solving the Problems A color image forming apparatus according to the present invention includes: an image signal generating unit that outputs image signals of a plurality of colors; and a recording that forms an image on an image carrier based on the image signals from the image signal generating unit. Control means for stopping image formation even when image formation is not completed by an emergency stop signal generated by an external operation after at least a part of image formation has been started, and returning operating conditions to an initial setting state , And white level clamping means for clamping the image signal level to a white level when an emergency stop signal is input.

When the emergency stop signal is input, the image signal level is clamped to the white level by the white level clamp means, and the image signal of this white level is output to the recording means. Then, the operating condition is automatically and reliably returned to the initial setting state by the control means.

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). Unit (5), transfer / separation unit (6), fixing device (7), and cleaning device (9)
And so on. 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 on the photosensitive drum (1) so as to be superposed.

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). The original is scanned by the lamp unit (17), and the image is scanned by the lamp unit (17) and the movable mirror unit (18).
The light is reflected by a mirror, and is sent to a lens (19) and a photo resolving prism (20). The light is split into three colors of red R, green G, and blue B, and is connected to an image sensor (21) that receives respective color images. Imaged. The received color image is photoelectrically converted into an electric signal corresponding to each color image, and further converted into an image signal for recording by an image processing unit.

FIG. 3 schematically shows the image processing section of the document reading unit (11).

The image processing unit is provided with three A / D converters (38) corresponding to the three image sensors (21). With these components, the output of each of the image sensors (21) is A / D converted and the color separation circuit ( Sent to 39). The color separation circuit (39) processes the outputs of the three AD converters (38) and outputs an image signal including color code data and density data to the gate circuit (40). The gate circuit (40) does not pass the image signal when the color code data is a white code, and otherwise passes the image signal and outputs it to the white level clamp circuit (41). And the color separation circuit (39) and the gate circuit (40)
Constitutes the image signal generation means. The white level clamp circuit (41) normally passes the image signal from the gate circuit (40) as it is to write the unit (3).
However, when an emergency stop signal, which will be described later, is input, the image signal level is clamped to a white level and constitutes a white level clamping means for outputting to the writing unit (3).

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 developers (25), (26) and (27) are individually operated 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.

A recording unit for forming a color image on the photosensitive drum (1) is constituted by the charger (2), the writing unit (3), the developing unit (4), and the like.

The paper supply unit (5) transfers the transfer paper to the photosensitive drum (1).
The paper supply means for supplying the paper to the printer comprises a paper feed cassette (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.

The operation panel (12) is provided with a start key (32), an emergency stop key (33), a condition setting unit (34) including various operation condition setting keys, respective indicators, and the like. The condition setting section (34) constitutes a condition setting means for setting an operation condition for copying.

The control unit (13) controls each part of the copying machine, and includes a microprocessor (CPU) (37), a program storage (35), a setting condition storage (36), and the like. The program storage unit (35) and the setting condition storage unit (36) are configured by a memory connected to the CPU (37). The program storage (35) stores a control program. The setting condition storage unit (36) constitutes a setting condition storage unit that stores the operating conditions set by the condition setting unit (34) of the operation panel (12). CPU
(37) constitutes control means for performing control of a color image forming process described later and emergency stop processing based on the control program stored in the program storage section (35). 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 sequence of the fixing device (7) and the cleaning device (9) is controlled by the CPU (37) based on the control program stored in the program storage (35).

Next, the outline of the operation of the above-described copying machine will be briefly described with reference to the flowchart of FIG.

When the power is turned on, first, necessary initial processing is performed (step 1), input data processing of the operation panel (12) is performed (step 2), and operation condition setting keys of the condition setting section (34) are operated. It is checked whether or not is pressed (step 3). If the setting key is pressed, the operating conditions are set (step 4), and the set operating conditions are stored in the setting condition storage section (36) of the control unit (13) (step 5). Return. If the setting key has not been pressed in step 3, it is checked whether the start key (32) has been pressed (step 6), and the start key (32)
The above operation is repeated until is pressed.

When the start key (32) is pressed in step 6, image formation is performed (step 7). When image formation is completed, the process returns to step 2 and the next copy is prepared. The image formation will be described later in detail.

When the emergency stop key (33) is pressed at any time after the power is turned on, for example, during image formation (step 8), an emergency stop process is performed by an interrupt process (step 9), and the copying machine is stopped immediately. The CPU (37) of the control unit (13) reads out the setting conditions stored in the setting condition storage section (36), and restores the operating conditions to the initial setting state (Step 10). Return to 6. The emergency stop processing will be described later in detail.

When the operation returns to step 6 after the emergency stop, the operating conditions have been restored to the initial state set immediately before. Therefore, only necessary conditions having an incorrect setting or the like are reset, and the start key (32 By pressing (), copying is performed.

In a conventional copying machine, even if an emergency stop is performed, the operating conditions are not automatically returned to the initial setting state. For this reason, after an emergency stop, a person must set necessary conditions again and copy again.
When the number of operation keys increases, the number of setting items that cannot be seen directly by a person increases. Therefore, it is difficult to clear and reset all erroneous conditions unless the person is familiar with the machine. In addition, after an emergency stop, a person can operate the reset key to return the operating conditions to the initial setting state.However, if you are in a hurry or if you are rushed to copy under wrong conditions, you can operate the reset key May be forgotten, and copying may be performed again under incorrect conditions.

On the other hand, in this copier, the operating conditions can be automatically and reliably returned to the initial setting state at the time of an emergency stop. Copying is possible, and there is little possibility that copying is performed again under wrong conditions.

The operation of image formation by the above copying machine is as follows.

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 operation 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. This electrostatic latent image for magenta toner recording is stored in a second developing device (2
The magenta toner image is further superimposed on the photosensitive drum (1) having the yellow toner image and developed by the operation of (6).

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 cassette (28) to the photosensitive drum (1), and the transfer / separation unit (6) is moved. 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. 5 is a time chart showing the progress of the image forming process in the above copying machine.

In FIG. 5, the solid line shows the process during normal operation, and each line is in the operating state while the upper line is in the “High” state, and the lower line is in the “Low” state. This indicates that the apparatus is in a dormant state for a certain period.

When the activation signal at time t ₀ start key is pushed is inputted, the photosensitive drum (1) starts rotating, at the same time, the charger (2) entirely charging the photosensitive drum and actuated (1) Let it. 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. together, the latent image formation for the yellow toner starts recording image exposure of the writing unit (3) is actuated (time t _1). The first developing device (25) is located near the head of the yellow latent image on the photosensitive drum (1).
, The first developing device (25) is activated to start developing with the yellow toner (time t ₂ ), which differs according to the recording length. This continues for about one revolution.

When the photoconductor drum (1) rotates and the vicinity of the head of the yellow toner image reaches the position of the charger (2) again, the photoconductor drum (1) is charged again, and the exposure of the original for magenta toner recording and the image formation are performed. Exposure is started (time t ₃ ). Further, the vicinity of the head of the magenta latent image on the photosensitive drum (1) is the second
When the developer reaches the position of the developing device (26), the second developing device (26) operates to start developing with the magenta toner (time point).
t ₄ ). 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 the cyan toner recording is started from the time t _5, but even more time t ₆ development with cyan toner is started, at the head near the transfer-separation unit (6) When it reaches (time t ₇ ),
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 cleaning device (9) (time point).
t ₈ ), the cleaning device (9) is 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 t ₉ ).

During this time, charging is at time t ₁₀ , and document exposure and image exposure are 3
The second time, that is, when the cyan image forming process is completed
At t ₁₁ , development is stopped at time t ₁₂ , transfer is stopped at time t ₁₃ , and cleaning is sequentially stopped at time t _14. At time t ₉ when the photosensitive drum (1) is stopped, all are returned to the initial state, ready for the next start. Can be The intervals at the respective times correspond to the distances of the respective devices on the photosensitive drum (1). In FIG. 5,
Arrows 1 to 4 indicate the times at which the photosensitive drum (1) makes one rotation and returns to the starting position after the start, from which it can be seen that one cycle is completed with four rotations of the photosensitive drum.

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

For example, after starting at time t ₁ , an emergency stop signal is input from the emergency stop key (33) at time T ₁ while document exposure for yellow toner recording, image exposure for yellow toner recording, and yellow toner development are in progress. In this case, the control unit (13) performs an emergency stop operation indicated by a dotted line in FIG. 5 according to a predetermined program. That is, the charging is stopped simultaneously with the input of the stop signal, and then the next and subsequent document exposure and image exposure (in this example, after document exposure and image exposure for magenta toner recording) and development (in this example, after magenta toner development) stopped, the front end of the developed yellow toner image is cleaning device at the time T ₂ has reached the opposite position (9) the operation of the cleaning device (9) to start the removal of the toner already deposited, the photosensitive drum (1) is complete and clean rotated by required length stops when T ₃ returned to almost start position,
It is possible to restart. The cleaning device (9) is stopped at the time T ₄ has ended the cleaning.

When the emergency stop signal is input, it is also input to the white level clamp circuit (41), whereby the image signal level is clamped to the white level by the white level clamp circuit (41), and is sent to the writing unit (3). Is output. Therefore, even if the image exposure and the development are not immediately stopped, the image formation is not actually performed.

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 an image forming apparatus other than the digital color copying machine as described above. For example, Japanese Unexamined Patent Publication
The present invention can be similarly applied to a transfer drum type analog color copying machine disclosed in Japanese Patent No. 13977.

According to the image forming apparatus of the present invention, as described above, image formation can be stopped at the same time as the input of the emergency stop signal, and extra toner is consumed until the apparatus stops in an emergency. There is no. Moreover, since the operating conditions can be automatically and reliably returned to the initial setting state at the time of an emergency stop,
The operation after the emergency stop is simple, it is hard to cause an error in the setting of the operating condition again, and therefore, there is little possibility that the operation such as copying is performed again under the incorrect condition.

[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 a block diagram of the image processing unit, FIG. 4 is a flowchart showing an outline of the operation of the copier, and FIG. 5 is a time chart showing an example of the operation of each unit during normal operation and emergency stop of the copier. . (1) photosensitive drum, (2) charger, (3)
... writing unit (4) ... developing unit (13)
... Control unit, (37) ... Microprocessor,
(39) Color separation circuit (40) Gate circuit (41)
.... White level clamp circuit.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takao Tsuda 1-0 Sakuracho, Hino-shi, Tokyo Konica Corporation Hino Factory (56) References JP-A-3-271785 (JP, A) JP-A Sho 61-234172 (JP, A) JP-A-62-142466 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 29/38 G03G 15/00

Claims (1)

(57) [Claims] 1. An image signal generating means for outputting image signals of a plurality of colors, a recording means for forming an image on an image carrier based on an image signal from the image signal generating means, and at least a part of image formation is started. Control means for stopping the image formation even when the image formation is not completed by an emergency stop signal generated by an external operation after the operation and returning the operation conditions to the initial setting state, and when an emergency stop signal is input. A color image forming apparatus including a white level clamp unit for clamping an image signal level to a white level.