JPH08137175A - Image forming device - Google Patents

Abstract

PURPOSE: To enable an operator to select an exchanging time even when the emptiness of a developing device is detected, and to facilitate exchanging processing in an image forming device provided with plural developing devices. CONSTITUTION: Four developing devices 31 are rotated clockwise as a whole and successively set at a developing position D. The remaining amount of developer in each developing device is detected according to the time when light emitted from a light emitting element 81 is reflected by a mirror 37 and arrives at a light receiving element 82. In the case of detecting that the developer is equal to or under a specified amount (the emptiness of the developing device), information on the developing device is stored in a memory in a control circuit and displayed on a display unit on a control panel. A key for inputting the designation of exchange is set adjacently to the display unit. By turning on the key, the developing device is moved to an exchanging position only when the information on the developing device the emptiness of which is detected is stored in the memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly to
The present invention relates to an image forming apparatus provided with a plurality of developing devices for forming a full-color image or a mono-color image on a recording sheet by electrophotography.

[0002]

2. Description of the Related Art Conventionally, in copying machines and printers in which a plurality of developing devices are switched to a developing position by a rotary system or an elevator system, the remaining amount of developer (toner) is detected for each developing device. When the empty is detected, it is displayed and the displayed developing device is moved to the exchange position by operating the input key. However, this requires as many replacement input keys as there are developing devices, and there is a risk of erroneous operation.

Further, as disclosed in Japanese Patent Laid-Open No. 60-260967, when the empty state of the developing device is detected, only one sheet in the copying at that time is copied, and then the empty state is automatically established. It has been proposed to move the developing device to the toner supply position. However, this method has a problem in that the operator cannot select the timing of developing device replacement (toner supply). That is, some sheets can be copied after the empty is detected, and even if the user wants to end the copy immediately, the copy cannot be continued unless the replacement or the replenishment is performed. Further, even if the developing device in which the empty is detected is yellow and it is desired to make a copy in black immediately, the developer must be replaced or replenished.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus in which the operator can select the replacement time even when the empty of the developing device is detected and the replacement process is easy. It is in.

In order to achieve the above object, the image forming apparatus according to the present invention stores a detecting means for detecting the remaining amount of the developer in each developing device and a developing device in which the empty is detected by the detecting means. Storage means, display means for displaying that the developing device is stored in the storage means, input means for instructing replacement of the developing device, moving means for moving each developing device to the replacement position, and the input means. Based on a replacement instruction from the storage unit, when the storage unit stores the developing device in which the empty is detected, the moving unit is operated to move the developing unit stored in the storage unit to the replacement position. Is equipped with.

In the above arrangement, the operator can identify that the developing device is empty by the display means. However, even in this case, it is possible to form an image using the remaining developer. On the other hand, when the operator inputs a replacement instruction from the input means, the developing device is replaced at a desired time. At this time, the developing device in which the empty stored in the storage means is detected is automatically moved to the replacement position. Therefore, the replacement work is easy, and there is no risk of accidentally moving another developing device to the replacement position.
The display means may simply display that one of the developing devices is empty, but it is preferable to display the type of the developing device that has become empty.

Further, in the image forming apparatus according to the present invention, the detecting means can detect the empty state at a first stage where image formation is not possible and a second stage where image formation is not possible, The control means has first and second control modes. The first control mode is to move the developing device to the replacement position when the developing device detected as being in the first stage is stored in the storage device based on the replacement instruction from the input device. Say that. The second control mode is to move the developing device detected by the detecting means to be in the second stage to the exchange position without waiting for the exchange instruction from the input means.

That is, even if the empty in the first paragraph is detected, the image formation can be continued unless the operator inputs a replacement instruction. However, when the second stage empty in which image formation is impossible is detected, the developing device replacement process (moving the developing device) is automatically started.

[0009]

Embodiments of the image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. The embodiment described below is an application of the present invention to a full-color laser beam printer.

(Overall Configuration of Printer) FIG. 1 shows the appearance of a full-color laser beam printer as seen from the front side, and FIG.
Indicates its internal mechanism. In FIG. 2, this printer is generally shown as a photosensitive drum 1 that is rotationally driven in the direction of arrow a.
1, a laser scanning optical unit 20, a full-color developing unit 30, an intermediate transfer unit 40 having an endless intermediate transfer belt 41 that is rotationally driven in the direction of arrow b, and a paper feed unit 60. It is composed of. In the photoconductor unit 10, a charging brush 12 and a cleaner 13 are further installed. Charging brush 12
Charges the surface of the photosensitive drum 11 uniformly to a predetermined potential. The cleaner 13 scrapes off the toner remaining on the photosensitive drum 11 by the blade 13a.

The laser scanning optical unit 20 is a well-known one having a laser diode, a polygon mirror and an fθ optical element built-in, and its control section has C (cyan), M (magenta), Y (yellow) and Bk (black). The print data for each is transferred from the host computer. The laser scanning optical unit 20 sequentially outputs the print data for each color as a laser beam, and scans and exposes the photosensitive drum 11. As a result, electrostatic latent images of respective colors are sequentially formed on the photoconductor drum 11.

The full color developing unit 30 includes C, M,
Four color developing devices 31C, 31M, 31Y, 31Bk containing a developer containing Y and Bk toners are integrated, and rotate in a clockwise direction with a spindle 39 as a fulcrum using a motor (not shown) as a drive source. It is possible. Each developing device is switched while rotating so that the developing sleeve 32 of the corresponding developing device is located at the developing position D each time an electrostatic latent image of each color is formed on the photosensitive drum 11. In this embodiment, the entire printer is made compact by using the rotary type full color developing unit 30.

In the intermediate transfer unit 40, the intermediate transfer belt 41 is endlessly stretched over the support rollers 42, 43 and the tension rollers 44, 45, and the photosensitive drum 1
It is driven to rotate in the direction of arrow b in synchronization with 1. A protrusion (not shown) is provided on the side portion of the intermediate transfer belt 41, and the microswitch 49 detects the protrusion to control image forming processing such as exposure, development, and transfer. The intermediate transfer belt 41 is pressed by the rotatable primary transfer roller 46 and comes into contact with the photosensitive drum 11, and this contact portion is the primary transfer portion. The intermediate transfer belt 41 is supported by the support roller 43 and faces a horizontal conveyance path 65 for a recording sheet, which will be described below, and is in contact with a rotatable secondary transfer roller 59. This contact portion is the secondary transfer portion.

Further, a cleaner 50 is installed in the intermediate transfer unit 40. The cleaner 50 has a blade 51 for scraping off the residual toner on the intermediate transfer belt 41. The blade 51 and the secondary transfer roller 59 can be brought into contact with and separated from the intermediate transfer belt 41. The paper feeding unit 60 includes a paper feeding tray 61 that can be opened on the front side of the printer body 1 (on which the operator is normally located), a paper feeding roller 62, and a timing roller 63. The recording sheets S are stacked on the paper feed tray 61 and are fed one by one to the right in FIG. 2 by the rotation of the paper feed roller 62, and are synchronized with the image formed on the intermediate transfer belt 41 by the timing roller 63. It is then sent to the secondary transfer section. The horizontal conveyance path 65 for the recording sheet is composed of an air suction belt 66, etc.
A vertical transport path 75 having 6, 77, 78 is provided. The recording sheet S is discharged from the vertical transport path 75 to the upper surface of the printer body 1.

(Full Color Printing Operation) Here, the outline of the full color printing operation in this embodiment will be described. At the start of the printing operation, the secondary transfer roller 59 and the cleaning blade 51 are separated from the intermediate transfer belt 41. When the printing operation is started, the photosensitive drum 11 is rotationally driven in the arrow a direction and the intermediate transfer belt 41 is rotated in the arrow b direction at the same peripheral speed, and the photosensitive drum 11 is charged to a predetermined potential by the charging brush 12. .

Subsequently, the laser scanning optical unit 20 exposes the cyan image, and an electrostatic latent image of the cyan image is formed on the photosensitive drum 11. This electrostatic latent image is immediately developed by the developing device 31C, and the toner image becomes 1
The image is transferred onto the intermediate transfer belt 41 at the next transfer portion. Immediately after the completion of the primary transfer, the developing device 31M is switched to the developing position D, and subsequently, the exposure, development and primary transfer of the magenta image are performed. Thereafter, similarly, switching to the developing device 31Y, exposure, development, and primary transfer of the yellow image are performed. Furthermore, switching to the developing device 31Bk, exposure and development of a black image, 1
Next transfer is performed, and the toner image is superposed on the intermediate transfer belt 41 for each primary transfer.

When the final primary transfer is completed, the developing unit 30 is switched to the developing unit 31C for the next printing process, and at the same time, the secondary transfer roller 59 and the cleaning blade 51 are pressed against the intermediate transfer belt 41. At this time, the recording sheet S is sent to the secondary transfer portion, and the full-color toner image formed on the intermediate transfer belt 41 is transferred onto the recording sheet S. When this secondary transfer is completed,
The secondary transfer roller 59 and the cleaning blade 51 are separated from the intermediate transfer belt 41.

(Opening and closing the printer body) Printer body 1
Is divided into a fixed side frame 2 and a movable side frame 5, as shown in FIG. The movable-side frame 5 can rotate about a support shaft 7, and the main body 1 can be opened by rotating the movable-side frame 5 toward the front side. Movable side frame 5
A cover 6 is installed on the main body 1, and the cover 6 constitutes a surface shell of the main body 1.

The stationary side frame 2 is provided with a laser scanning optical unit 20, a developing unit 30, a sheet feeding section 60, a horizontal conveying path 65, a fixing device 70, a vertical conveying path 75 and the like. The photosensitive unit 10 and the intermediate transfer unit 40 are installed on the movable frame 5. When the movable side frame 5 is opened, the main body 1 has the developing unit 30 and the paper feeding section 6
0, the horizontal conveyance path 65 is opened almost entirely so that it can be accessed from the outside. In this open state, the photoconductor unit 10 and the intermediate transfer unit 40 are attachable to and detachable from the movable-side frame 5, and each developing device 31 also has the developing unit 3.
It can be attached to and detached from the developing position D with respect to 0.

(Structure of Developing Unit) Developing unit 30
As described above, the four independent developing devices 31C, 31
M, 31Y, and 31Bk are detachably attached to the developing rack 38, and can rotate with a spindle 39 as a fulcrum by a motor (not shown). As shown in FIG. 4, each developing device 31 has a developing sleeve 32, a regulating blade 33, a developer chamber 34, a developer accommodating chamber 35, a developer stirring member 36, and a mirror 37. The developer is scraped out of the storage chamber 35 through the opening 35a into the developing chamber 34 as the stirring member 36 rotates in the clockwise direction, and on the surface of the photosensitive drum 11 as the developing sleeve 32 rotates in the counterclockwise direction. Supplied.

At the center of the developing unit 30, a set of a light emitting element 81 and a light receiving element 82 is fixed to the fixed side frame 2, and a developing device set at a developing position D (corresponding to the developing device 31C in FIG. 4). The residual amount of the developer in the accommodation chamber 35 is detected by the reflected light from the mirror 37 of (1). Light emitting element 81
The light emitted from the mirror is transmitted through the accommodation chamber 35 and the mirror 37.
Is received by the light receiving element 82. When the developer is sufficiently stored in the storage chamber 35, the light from the light emitting element 81 does not reach the light receiving element 82, but reaches when the remaining amount is small. The remaining amount of the developer can be detected by this arrival time, and when the arrival time is equal to or less than the reference time Ta, the developing device is detected as empty. The reference time Ta is the remaining amount of the developer, but some still refer to the arrival time in a printable state.

On the other hand, in order to identify the developing device at the developing position D at the time of detection, four types of photo interrupters 83C, 83M, 83Y and 83Bk are fixed to the fixed side frame 2.
In addition, each of the developing devices has a projecting piece 84 at a position that blocks the optical axis of each photo interrupter when set at the developing position D.
C, 84M, 84Y and 84Bk are projected. Therefore, if the photo interrupter 83C is now closed, it is currently set at the developing position D, in other words,
The type of the developing device for which the remaining amount of the developer is detected by the light receiving element 82 can be determined.

By the way, the replacement position of the developing device is a position A slightly rotated clockwise from the developing position D, as shown in FIG. As described below, when replacing the developing device, the motor is driven to set the developing device to be replaced at the position A.

(Operation Panel and Control Circuit) As shown in FIG. 1, this printer has an operation panel 90 on the front side. On the operation panel 90, a display 91 for displaying a developing device in which the empty is detected, an input key 92 for instructing replacement of the developing device, and the like are installed.

The control circuit, as shown in FIG.
00, its program memory 101, and I / O port 10
2, a memory 103, an input interface 104, a drive circuit 105 and the like. The input interface 104 includes a light receiving element 82 for detecting the empty and photo interrupters 83C, 83M, 83 for detecting the developing device.
A signal from Y, 83Bk is input. Drive circuit 1
A motor 106 for rotating the developing unit 30 is connected to 05. In addition, the display 9 on the operation panel 90
1, the input key 92 is the CPU via the I / O port 102
It is connected to 100.

In the above control circuit, the CPU 100
When an empty detection signal (light arrival time is equal to or less than the reference time Ta) is input from the light receiving element 82, it determines which developing device is empty based on the signal from the photo interrupter 83, and outputs the information. It is stored in the memory 103. At the same time, the display 91 is displayed. The operator confirms the display on the display unit 91 and determines whether or not to replace the empty developing unit immediately. For example, immediately after the empty is displayed, several print processes can be performed, so that priority is given to it. Alternatively, if the developing device in which the empty is displayed is for yellow and black monocolor printing is to be performed from now on, that may be prioritized.

When it is necessary to replace the key, the input key 9
Turn on 2. The CPU 100 is now in the drive circuit 1
A drive signal is issued to the developing device 05 to move the developing device, which is detected as empty, to the replacement position A. Therefore, the operator opens the movable frame 5 and replaces the developing device. The memory 10 is used to move the developing device to the exchange position A.
This is only when the developing device in which the empty is detected is stored in No. 3, and the movement to the exchange position A is not executed even if the input key 92 is turned on other than this condition.

(Control Procedure) Next, the control procedure when the developing device is replaced by the control circuit will be described with reference to the flowchart of FIG. First, in step S1, it is determined whether or not the developing device at the detection position is empty, that is, whether or not the light arrival time at the light receiving element 82 is the reference time Ta or less. If it is empty, the empty is detected in step S2 and the developing device is stored in the memory 103 and displayed on the display 91. Next, in step S3, the input key 92 is waited to be turned on, and when it is turned on, the developing device detected as empty in step S4 is moved to the exchange position A.

(Second Embodiment) In the second embodiment, the empty state of the developing device is detected in two stages, and a replacement mode is adopted in accordance with the detected empty state. The configuration of the device is similar to that shown in FIGS. The first stage of empty detection is when the light arrival time at the light receiving element 82 is Ta (referred to as a first reference time). At this time, some developer that can be printed remains in the developer accommodating chamber 35. The second stage is the light arrival time Tb (referred to as the second reference time).
When: The second stage is a case where the printing process is continued even after being detected as the first stage, and at this time, almost no developer remains in the developer accommodating chamber 35,
Normal print processing is impossible.

In the developing device at the detection position, the fact that the light arrival time is less than or equal to the first reference time Ta and less than or equal to the second reference time Tb is stored in the memory 103. When the first stage is detected, the same exchange control as in the first embodiment is performed. On the other hand, when the second stage is detected, the developing device is forcibly moved to the exchange position A without waiting for the ON signal from the input key 92.

Specifically, as shown in FIG. 8, it is determined in step S11 whether or not the developing device at the detection position is in the first stage of empty, that is, whether or not the light arrival time is the first reference time Ta or less. To do. If it is the first reference time Ta or less, the empty is detected and the developing device is stored in the memory 103 and displayed on the display 91 in step S12. In the case of the empty second stage, the developing device is stored in the memory 103. Next, when it is confirmed that the input key 92 is turned on in step S13, the corresponding developing device is moved to the exchange position A in step S15.

On the other hand, even if it is not confirmed that the input key 92 is turned on in step S13, it is determined in step S14 whether or not it is the empty second stage, that is, whether or not the light arrival time is the second reference time Tb or less. If the second reference time Tb or less,
Immediately in step S15, the corresponding developing device is moved to the replacement position A. According to the second embodiment, in addition to the effect of the first embodiment that the operator can select the timing for replacing the developing device, it is possible to prevent incomplete execution of print processing.

(Other Embodiments) The image forming apparatus according to the present invention is not limited to the above embodiments, but can be variously modified within the scope of the gist thereof. For example, instead of printing out an image with print data from an external device,
The present invention can also be applied to a full-color copying machine equipped with a document image reading means.

The present invention can also be applied to a printer or a copying machine that forms an image in some mono colors instead of in full color. The moving type of the developing device may be an elevator type other than the rotary type. Alternatively,
For a developing unit of the type that replenishes toner, the developing unit in which the empty is detected may be moved to the toner replenishment position. Further, the present invention is not limited to the empty state, and when some trouble occurs in the developing device, the developing device may be moved to the replacement position or the maintenance position.

[Brief description of drawings]

FIG. 1 is a perspective view showing the outer appearance of a full-color laser beam printer which is an embodiment of the present invention.

FIG. 2 is an internal structural view of the printer, in which a movable frame is closed.

FIG. 3 is an internal structural view of the printer, in which a movable frame is open, a photoconductor unit, an intermediate transfer unit,
The developing device is taken out.

FIG. 4 is a sectional view showing a developing unit.

FIG. 5 is a cross-sectional view showing the developing unit in a state where the developing device is set to the exchange position.

FIG. 6 is a block diagram showing a control circuit.

FIG. 7 is a flowchart showing a control procedure as the first embodiment.

FIG. 8 is a flowchart showing a control procedure as a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printer main body 30 ... Developing unit 31 ... Developing device 39 ... Rotating spindle 81, 82 ... Empty detection means (light emitting element, light receiving element) 91 ... Display 92 ... Exchange input key 100 ... CPU 103 ... Memory

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Claims (3)

[Claims] 1. An image forming apparatus having a plurality of developing devices, comprising the following structure: detecting means for detecting the amount of developer remaining in each developing device; emptying detected by the detecting means. Storage means for storing the developed developing device; display means for displaying that the developing device is stored in the storage means; input means for instructing replacement of the developing device; moving means for moving each developing device to a replacement position; Based on the replacement instruction from the input unit, when the storage unit stores the developing unit whose empty is detected, the moving unit is operated to move the developing unit stored in the storage unit to the replacement position. Control means. 2. An image forming apparatus having a plurality of developing devices, comprising the following structure: detecting means for detecting the remaining amount of the developer in each developing device in two steps, a first step. Indicates a stage where the remaining amount is small but the image cannot be formed, and the second stage indicates a stage where the remaining amount is small and the image cannot be formed; storage means for storing the developing device in which the empty is detected by the detecting means; Display means for displaying that the developing device is stored in the storage means; Input means for instructing replacement of the developing device;
Moving means for moving each developing device to the exchange position; control means for operating the moving means to move the developing device to the exchange position; the control means stores the first data in the storage means based on the exchange instruction from the input means. When the developing device detected as the stage is stored, the first control mode for moving the developing device to the exchange position and the developing device detected by the detecting means as the second stage are input. And a second control mode for moving to the exchange position without waiting for the exchange instruction from the means. 3. The image forming apparatus according to claim 1 or 2, wherein the display unit displays a type of the developing device in which the empty is detected.