JP2000356901A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact electrophotographic device capable of accurately judging the existence or the remaining amount of developer in a developing device at low cost by providing a light emitting means and a light receiving sensor for detecting light from the light emitting means and judging the existence or the remaining amount of the developer according to AC component output from the light receiving sensor. SOLUTION: A transmission window 5 is provided at a position where both side plates of the developing device are opposed and covered with a transparent member. The window 5 is in the radius of the rotation of an agitator and in the radius of the rotation of a gear 10 driving the agitator. The light emitting means 50 and the light receiving sensor 51 are installed at positions where the side plates of a printer main body are aligned with the window 5. The sensor 51 is connected to a control substrate through a harness. The light from the means 50 is detected by the sensor 51 through the window 5 provided on the developing device, and the developer amount is judged from the AC component of the output from the sensor 51. Thus, the existence or the remaining amount of the developer is judged with simple constitution at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic apparatus used for a copying machine, a printer, a facsimile, etc., for forming an image with a plurality of color developers.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a toner in a developer is adsorbed on an electrostatic latent image formed on a photoreceptor to form a toner image, and the toner image is transferred onto a transfer medium. An image is formed by fixing by heat and pressure. The development of the electrostatic latent image is performed by a developing device that stores the developer, and information on the amount of the developer stored in the developing device is important for maintenance management. For example, in a developing device that replenishes toner from a toner cartridge, if a toner end occurs during image formation, the toner cartridge cannot be used without a spare toner cartridge.

A method for avoiding such a situation is disclosed in Japanese Patent Publication No. 62-502, Japanese Patent Application Laid-Open No. 6-19314, Japanese Patent Application Laid-Open No. 10-186822, and Japanese Patent Application Laid-Open No. 10-2.
88884, JP-A-10-133465,
JP-A-10-171232 and JP-A-10-26
No. 0577. Tokuhei 62-502
The method disclosed in Japanese Patent Application Laid-Open No. Hei 6-19314 discloses a method for mechanically detecting a drive load torque of an agitator that conveys and agitates toner in a developing device as means for detecting toner end. In the method shown in the above, the developer remaining amount detecting means for detecting the presence or absence of the developer is arranged near the final agitator closest to the developing sleeve among the plurality of agitators for stirring the developer, so that the remaining amount of the developer is reduced. The detection is performed in multiple stages, and the flow rate of the developer conveyed to the developing roller is maintained uniformly.

In the method described in Japanese Patent Application Laid-Open No. H10-186822, the transmission time of light passing through a toner cartridge is measured to continuously detect the remaining amount of toner. It is displayed as a change over time. Similarly, in the method disclosed in Japanese Patent Application Laid-Open No. 10-288888, a table indicating the relationship between the remaining amount of developer and the pulse width of the remaining detection force by the remaining amount of developer detecting unit is created in advance, and the remaining amount of developer is detected. The remaining amount of developer is estimated based on the remaining detection power pulse, and a warning of "small amount of developer" is issued at a predetermined value. Further, JP-A-10-133
The method disclosed in Japanese Patent Application Publication No. 465-465 uses a light-emitting sensor and a light-receiving sensor to detect the presence or absence of a developer filled in the developing device, and turns off the light-emitting sensor and the light-receiving sensor when operation is unnecessary. In addition, power consumption is reduced. Further, the method disclosed in Japanese Patent Application Laid-Open No. 10-171232 discloses a method in which a first light guide for guiding light from a light emitting member to a first light transmitting portion and a light passing through the second light transmitting portion to a light receiving member. This is a technique for improving the accuracy of detecting the remaining amount of toner by providing a second light guide for guiding. Furthermore, Japanese Patent Laid-Open No.
The method disclosed in Japanese Patent Application Laid-Open No. 0-260577 includes a light emitting unit and a light receiving unit capable of detecting a change in the amount of transmitted light accompanying stirring of the toner by a paddle, and detects the remaining amount of toner by processing the output of the light receiving unit by a CPU. Is the way.

[0005]

However, in the above-mentioned prior art, high accuracy cannot be required by mechanical detection. Therefore, the use of a special sensor leads to an increase in cost. In addition, the method using light transmission requires a high-output element as a light-emitting element and a high-performance element as a light-receiving element when the concentration of powder is high, resulting in reduced reliability and cost. There is a problem of rising. For example, when detecting the remaining amount of the developer, Japanese Unexamined Patent Application Publication Nos.
The method described in Japanese Patent Application Laid-Open No. 0-186822 makes a determination based on the fact that the pulse width changes according to the remaining amount of the developer and the voltage level of the detection signal changes according to the remaining amount of the developer. However, these methods cannot detect the remaining amount of the developer when a developer having a high pigment concentration is used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a small-sized electrophotographic apparatus capable of accurately determining the presence or absence or remaining amount of a developer in a developing device at low cost. It is to provide a device.

[0007]

In order to solve the above-mentioned problems, the present invention is directed to a photosensitive member on which an electrostatic latent image is formed according to color-coded print data; A developing sleeve having a pair of transmission windows at opposite positions, filled with developers of different colors and carrying the developer on the surface, and a developing sleeve driving means for rotating and driving the developing sleeve. A plurality of detachable developing devices for developing an electrostatic latent image on the photoreceptor, a light emitting unit disposed opposite to a position corresponding to the pair of transmission windows via the developing device, and a light emitting unit. An electrophotograph comprising: a light receiving sensor that detects light; and a developing device contacting / separating unit that fixes the developing device of a corresponding color at a developing position close to the photoconductor at the start of development and separates the developing device from the photoconductor after development is completed. In the apparatus, A light shield that moves in synchronization with the rotation of the developing sleeve between the image sleeve driving means and the light emitting means, between the light emitting means and the light receiving sensor, and between the developing sleeve driving means and the light receiving sensor. Means, the output of the AC component of the light receiving sensor,
Provided is an electrophotographic apparatus including a developer amount determining unit that determines the presence or absence or the remaining amount of a developer.

According to a second aspect of the present invention, the light-shielding means is a gear or an agitator provided so that the transmission window is disposed within a rotation radius and having at least one window through which light is transmitted. 2. The electrophotographic apparatus according to claim 1, wherein light from the transmission window of the developing device or light to the transmission window is periodically shielded in synchronization with the developing sleeve.

According to a third aspect of the present invention, the light emitting means is an LED, the light receiving sensor is a phototransistor, and an emitter of the phototransistor is connected to GND.
, The collector of the phototransistor is connected to a power supply, a resistor is connected in series to the emitter or the collector, one end of the resistor is connected to an amplifier via a capacitor, and the output of the amplifier is connected to a microcomputer. An electrophotographic apparatus according to claim 1 or 2, which is connected to an input port.

According to a fourth aspect of the present invention, the light emitting means is an LED, the light receiving sensor is a phototransistor, and an emitter of the phototransistor is connected to GND.
, The collector of the phototransistor is connected to a power supply, a resistor is connected in series to the emitter or the collector, one end of the resistor is connected to an amplifier via a capacitor, and the output of the amplifier is connected to a microcomputer. 3. A connection to an AD conversion input.
The present invention provides an electrophotographic apparatus described in (1).

According to a fifth aspect of the present invention, there is provided a photoreceptor on which an electrostatic latent image is formed in accordance with color-coded print data, and a pair of transmissive windows at opposing positions on both side surfaces. A developing sleeve filled with developers of different colors and carrying the developer on a surface thereof; and a developing sleeve driving unit for driving the developing sleeve to rotate. A developing device capable of: a light emitting unit disposed opposite to a position corresponding to the pair of transmission windows via the developing device; a light receiving sensor for detecting light from the light emitting unit; and a developing device of a corresponding color. An electrophotographic apparatus having a developing device contacting / separating unit that is fixed at a developing position close to the photoconductor at the start of development, and is separated from the photoconductor after development is completed; ,Previous A light-shielding unit that moves between the light-emitting unit and the light-receiving sensor and between the developing sleeve driving unit and the light-receiving sensor in synchronization with the rotation of the developing sleeve; Provided is an electrophotographic apparatus including a detecting unit and a developer amount determining unit configured to determine the presence or absence or the remaining amount of the developer based on an output of an AC component and a DC component of the light receiving sensor.

According to a sixth aspect of the present invention, the developer amount judging means includes means for detecting the DC component of the output of the light receiving sensor during a maximum of four rotations of the developing sleeve after the driving of the developing sleeve is started. The electrophotographic apparatus according to claim 5, wherein the presence or absence or the remaining amount of the developer is determined based on the presence or absence or the size.

According to a seventh aspect of the present invention, the developing device includes a developing sleeve decelerating means for reducing the rotational speed of the developing sleeve to half or less, and the developer amount judging means comprises a developing sleeve decelerating means. 6. The electrophotographic apparatus according to claim 5, wherein after the rotation speed of the developing sleeve is reduced by means, the presence or absence or the remaining amount of the developer is determined based on the presence or absence or magnitude of the DC component of the light receiving sensor.

According to an eighth aspect of the present invention, the developer amount judging means includes a first developer amount judging means for detecting the presence or absence or magnitude of an AC component of the output of the light receiving sensor; A second developer amount determination unit for detecting the presence or absence or magnitude of a DC component, wherein the first developer amount determination unit indicates that the end of the developer amount is near, and the second developer amount An electrophotographic apparatus according to any one of claims 5, 6 and 7, wherein the amount judging means indicates that there is no developer and judges the prohibition of use of the developing device.

According to a ninth aspect of the present invention, the light emitting means is an LED, the light receiving sensor is a phototransistor, and an emitter of the phototransistor is connected to GND.
, A collector of the phototransistor is connected to a power supply, a resistor is connected in series to the emitter or the collector, another end of the resistor is connected to one end of a capacitor, and the other end of the capacitor is connected to an operational amplifier. , A switch element is connected in parallel with the capacitor, and two resistors are arranged in series.
A connection point between the two resistors D, a connection point of the two resistors is connected to a non-inverting input of the operational amplifier, and an output of the operational amplifier is connected to an input port or an A / D input of a microcomputer. 6. An electrophotographic apparatus according to claim 7 or 8 is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electrophotographic apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a color laser printer which is an embodiment of the electrophotographic apparatus of the present invention. FIG. 12 is a block diagram showing an outline of the electrical equipment of the color laser printer. This color laser printer uses an endless photosensitive belt 2.
Numeral 0 is stretched by a driving roller 17, a driven roller 18, and a tension roller 27, and is driven to rotate by the driving roller 17. Around the photoreceptor belt 20,
Scorotron charger 21, laser generator (not shown) for irradiating laser beam 19 to photoreceptor belt 20, developing devices 1, 2, 3, 4, transfer device and fixing device 3
0 is provided. As shown in FIG. 12, a high voltage power supply C is connected to the wire of the scorotron charger 21.
A high-voltage power supply G is connected to the grid, and the photosensitive belt 20
Is controlled to an optimum potential by the scorotron charger 21.

The developing devices 1, 2, 3, and 4 are filled with developers of four different colors, respectively, and include a first developing device 1, a second developing device 2, a third developing device 3, and a fourth developing device. The developing device 4 is arranged in parallel with the photosensitive belt 20. Each of the developing devices 1, 2, 3, and 4 is housed in a housing,
The developing sleeve 6 is provided at the opening facing the photoreceptor belt 20.
a, 6b, 6c and 6d are provided. As shown in FIG. 12, the developing sleeves 6a, 6b, 6c, and 6d are connected to a high-voltage power supply D, are applied with a bias voltage, and are controlled so as to obtain optimal developing conditions. Each developing device 1,
Behind the developing sleeves 6a, 6b, 6c, 6d in 2, 3, 4, agitators and a plurality of gears 7, 8, 9, 1,
0, 11, and 12 are arranged. Fig. 5
A mylar sheet 43 having a hole as shown in FIG. 7 is bonded to the shaft 42, and both ends thereof are reinforced with hard plate members 40 and 41. The shaft rotates to move the developer. Transmission windows 5a, 5b, 5c, and 5d are provided at positions on both sides of the developing devices 1, 2, 3, and 4 near the bottom surface of the developing device. FIG. 6 is an outline of the periphery of the transmission window 5 of the developing device, and is a diagram showing a state in which the developing device is fixed at the developing position. The transmission window 5 is provided at a position opposite to both side plates of the developing device, and is closed by a transparent member. The transmission window 5 is within the radius of rotation of the agitator 44 and
In the radius of rotation of the gear 10 that drives. Gear 10
Has eight voids formed by eight ribs as shown in FIG.

The transfer device comprises a transfer belt 22 stretched by a plurality of rollers, a transfer roller 23, a cleaning roller 24, and a paper transfer roller 25, such that a part of the transfer belt 22 contacts the photosensitive belt 20. It rotates while being stretched. As shown in FIG. 12, the transfer roller 23 is connected to a high-voltage power supply T <b> 1, which controls the developer on the photoconductor to move to the transfer belt 22 appropriately. The paper transfer roller 25 is connected to the high-voltage power supply T2, and is thereby controlled so that the developer on the transfer belt 22 moves to the recording paper without fail. The cleaning roller 24 is connected to a high-voltage power supply CL and is applied with a bias voltage. When the image transfer to the recording paper is completed, the developer remaining on the surface of the transfer belt 22 is removed by the cleaning roller 2.
4 to be collected. Further, a paper transport roller 26 and a fixing device 30 are provided near the transfer device, and the toner image transferred to the transfer belt 22 is transferred to the paper transport roller 26.
After being transferred onto the transfer paper conveyed by the fixing device 30, it is heated and pressed by the fixing device 30 to be fixed.

When printing is performed by the above-described color laser printer, first, the photosensitive belt 20 is uniformly charged by the scorotron charger 21, and a first color latent image is drawn thereon by the laser 19, and the first color latent image is drawn by the laser 19. Is developed by the first developing device 1 corresponding to the color of. The developed image on the photosensitive belt 20 is transferred to the transfer belt 22 by the transfer roller 23. On the other hand, the photoreceptor belt 20 is uniformly charged again, a latent image of the second color is drawn by the laser, and is developed by the second developing device 2. The developed image is transferred over the transfer belt 22. Similarly, after the fourth image is superimposed on the transfer belt, the image on the transfer belt 22 is transferred to the transfer paper sent from the paper transport roller 26, fixed by the fixing device 30, and the printing is completed. I do. When the above-described color laser printer is used for only black and white images, control is performed so that only the developing device containing the black developer is used. Also, when using for a special color, control is performed so that only a necessary one of the four developing devices is used.

A first cam 13, a second cam 14, a third cam 15, and a third cam 15, which correspond to the photoreceptor belt 20 via the developing devices 1, 2, 3, and 4, respectively. 4 cams 16 are provided, and these cams 13, 14, 1
By the rotation of 5, 16 the corresponding developing devices 1, 2,
3 and 4 are configured to be pushed out toward the photoreceptor belt 20 side. The contact and separation of the developing device with the photoreceptor belt are performed as follows. Four developing devices 1, 2, 3,
4, one of the photoreceptor belts 2 is provided by a corresponding cam.
It is pressed to the 0 side, and the other developing devices are open.
For example, in FIG. 3, the first cam 13 is pressed against the first developing device 1, and the first developing device 1 is fixed at a developing position close to the photosensitive belt 20. In the first developing device 1 fixed at the developing position, the first developing clutch is turned on.
, The gear 7 attached to the shaft of the developing sleeve rotates, and the first developing sleeve 6 rotates. At the same time, the transmission gears 8 and 11 rotate, and the gears 10 and 12 attached to the agitator shaft rotate. The gear 9 is driven by the gear 10 to rotate the agitator.

As shown in FIG. 6, a light emitting means 50 and a light receiving sensor 51 are provided at positions corresponding to the transmission windows 5 on the side plate of the printer body. FIG. 3 shows an example of a light receiving sensor and a subsequent circuit. The light receiving sensor has four phototransistors PT1, PT2, PT3, and PT4 attached to a printed circuit board. First developing device and first phototransistor PT1, second developing device and second phototransistor PT2, third developing device and third phototransistor PT3, fourth developing device and fourth phototransistor PT4 is supported. The light receiving sensor is connected to the control board by a harness. On the control board, the emitter of PT1 is grounded, the collector is diode D10 and resistor R
10 and connected to a 5V power supply.
The non-inverting input terminal 9 of the IC 10 is connected to the inverting input terminal 8 of C10 via a capacitor C10 and a resistor R11, and the feedback resistor R12 is connected to the output terminal 14 pin.
The pin is connected to GND. If the fluctuation of the transmitted light is slight even in the PT1, a large AC waveform can be obtained in the output of the IC 10. The output of IC10 is a microcomputer IC
1 input port. The resistor R14 is for pull-up. Second phototransistor PT2, third phototransistor PT3, fourth phototransistor P
T4 has the same configuration and is connected to each input port of IC1. In this embodiment, the emitter of the phototransistor is connected to the ground, and the connector is connected to the 5V power supply via the diode D10 and the resistor R10. However, a resistor is connected between the emitter and the ground, and the collector is connected to the 5V power supply. Can be connected.
Further, in the present embodiment, the output of the operational amplifier IC10 is connected to the input port of the microcomputer IC1, but this may be connected to the AD conversion input of the IC1.

FIG. 2 is a diagram showing the light emitting means and its related circuits. Four LEDs (LD1, LD2, LD3, LD
4) and two resistors (R1, R2) and a capacitor (C1)
Is attached to the printed circuit board. The light emitting means is connected to a 5V power supply by a harness. The LEDs are connected in series two by two, and the anode side has a current limiting resistor R1,
R2 is connected to a 5V power supply, and the cathode side is connected to ground.

FIGS. 8, 9 and 10 show the collector waveforms of the phototransistor PT1 in the circuit shown in FIG. As described above, since there is a light blocking member such as a gear between the light emitting means and the light receiving sensor, the output of the light receiving sensor must be used to determine the presence or absence of the developer or the remaining amount unless these light blocking members are driven. Can not be used for. FIG. 8 shows a state in which the developing device is driven, the developer is sufficiently stirred by the agitator, and the remaining amount of the developer is lower than the reference of the light receiving sensor. Since a developer having a high pigment concentration floats, a sufficient amount of transmitted light cannot be obtained, and a slight AC waveform is obtained. This AC waveform is generated due to light shielding of the light receiving sensor by a gear or a scraper, and is AC amplified,
Input to the microcomputer. When the remaining amount of the developer is equal to or higher than the reference of the light receiving sensor, the light is shielded by the non-floating developer itself, so that the collector waveform becomes a DC waveform without fluctuation. Then, it is possible to determine whether or not the remaining amount of the developer has decreased based on the presence or absence of the AC component, and to prompt the preparation for the developer replenishment. At this time, by changing the mounting position of the light receiving sensor, it is possible to detect that the amount of the developer has decreased to a level at which the use of the developing device is prohibited, and to prohibit the use of the device. The output of the operational amplifier is monitored at the input port of the microcomputer, and the remaining amount or the presence or absence of the developer is determined from the presence or absence of the high level H or the low level L, the number of times or the duration thereof.

In this embodiment, the output of the operational amplifier is monitored by the input port of the microcomputer. However, the output is monitored by the A / D input of the microcomputer, and the remaining amount of the developer is monitored in accordance with the level. Can be determined in detail, which is suitable when high functionality is required. When the determination is made based on a change in the level of the light receiving sensor, the output of the light receiving sensor is directly connected to the AD conversion input of the microcomputer without using a comparator. In order to obtain the average value of the output, the average value of the A / D conversion input of the microcomputer is obtained by calculation, or an integration circuit is added before the A / D conversion input. Further, in this embodiment, an AC amplifier circuit is used as shown in FIG. 3, but a configuration in which AC amplification and DC amplification are switched as shown in FIG. 7 can be adopted. In this case, the AC coupling capacitor C10 of the AC amplification circuit in FIG. 3 can be short-circuited by the photocoupler PC1. When PC1 is turned on, DC coupling is established, so that the output of the light receiving sensor can be detected in a DC manner.

FIG. 9 shows a state in which a developer having a low pigment (dye) concentration is used and the developer is sufficiently stirred, or a developer having a high pigment (dye) concentration is used and the developer is almost empty. FIG. 4 is a diagram showing a collector waveform when the collector is turned on. The collector waveform is at the high level when the light is blocked by the gear or the agitator, but when the light is not shielded, the transmitted light is received and the collector waveform swings to the low level. This state is determined by the microcomputer as a DC component. In this manner, the near end of the developer can be detected by the AC component, and the end (empty) of the developer can be detected by the DC component. When a developer having a high pigment concentration is used and the rotational speed of the developing sleeve is reduced to half or less when the remaining amount of the developer is equal to or less than a predetermined amount, the time axis is different, but FIG. Since the collector waveform is substantially similar to the above, the near end of the developer can be detected by the AC component, and the end of the developer can be detected by the DC component when the rotation speed of the developing sleeve is halved.

By the way, even when a toner having a high pigment concentration is used, if the light emitting means is an ultra-high-brightness LED or the like and the amount of emitted light is several times that of a general-purpose LED, a waveform substantially the same as that of FIG. 7 can be obtained. . In this case, there is a problem that side effects accompanying an increase in the cost of the LED such as fatigue of the toner due to light increase. It is also conceivable to use a general-purpose LED to improve the performance of the phototransistor.
It is greatly affected by external noise, and the countermeasures complicate the circuit and the mechanism of the light receiving section, thereby increasing the cost and reducing the reliability. FIG. 10 is a diagram showing a collector waveform immediately after the developing device is driven using a developer having a high pigment concentration in the electrophotographic apparatus of the present embodiment. At the beginning, even if the pigment concentration is high, a collector waveform almost equal to that of FIG. 8 is obtained, and the change is small with time, and the pigment concentration is maintained until the developer is agitated and floats in the developing device. This indicates that the circuit using the general-purpose LED can sufficiently detect the end of the developer even if the developer has a high value. Therefore, the near end of the developer can be detected by the AC component, and the end of the developer can be detected by the DC component immediately after driving the developing device. In addition, since the density of the floating developer changes according to the remaining amount of the developer, and the collector waveform changes accordingly, even if the developer having a high pigment concentration is almost empty, the developer to be detected is almost empty. The concentration of the floating developer decreases, and a waveform substantially equivalent to the waveform shown in FIG. 9 can be obtained even during driving of the developing device. Therefore, the near end of the developer can be detected by the AC component, and the end of the developer can be detected by the DC component.

FIG. 12 is a block diagram showing an outline of the electrical equipment. A main control unit MCU including a peripheral circuit centered on a my computer (IC1 in FIG. 3) includes a belt motor BM for driving the photosensitive belt 20 and the transfer belt 22 shown in FIG. , A conveying motor PM for driving the paper conveying roller 26, the fixing device 30, a developing clutch DC1, DC2, DC3, DC4 for intermittently driving the developing sleeve of the developing device, and moving the developing device to and from the developing position. ON / OFF clutches CC12 and C
C34, a high-voltage power supply, a light-emitting means LD for detecting the presence or absence of a developing device and empty developer, and a light-receiving sensor PT1,
It controls PT2, PT3, PT4 and the heater. Although not shown, the MCU additionally has functions such as control of laser writing. The heater HEAT of the fixing roller detects the temperature with a thermistor TH and is controlled to a predetermined temperature by heater control.

FIG. 11 shows a subroutine for judging the near end of the developer (near end) and a subroutine for judging the end of the developer (end 1) in this embodiment, and a subroutine for judging the end of the developer in another embodiment. It is a flow figure of (end 2). In the near-end subroutine, the photocoupler PC1 in FIG. 7 is turned off (PC1 = O) in order to detect an AC component while the developing device is driven.
FF), and it is checked whether the output of the phototransistor at that time changes to high H or low L (PTL = L / H). When such a change is observed in the output of the phototransistor (Y), a near-end flag is set (fnear = 1), and the process exits the subroutine. When this flag is set, it is displayed on the operation unit that the remaining amount of the developer is low, or a predetermined process is performed. The end 1 subroutine is a flowchart for detecting the end of the developer by looking at the DC component. First, turn on the photocoupler in FIG.
(PC1 = ON) to detect the DC component, and check whether the output of the phototransistor becomes low L (PT1 = L). If the output of the phototransistor is low L (Y), an end flag (fend = 1) is set, and the process exits the subroutine. When the end flag is set, processing for prohibiting use of the electrophotographic apparatus is performed. End 2 subroutine
FIG. 8 is a flowchart for detecting a DC component immediately after driving a developing sleeve to determine whether or not the developer is at an end; Turn on photocoupler PC1 (PC1
= ON), and then turn on the developing clutch DC1 (DC1 = O
N), and if the output of the phototransistor PT1 immediately thereafter is L (PT1 = L), the end flag (fend = fend =
Set 1) and exit from the subroutine. When fnear rises, the developer is almost exhausted in the main flow, so a display is displayed to prepare, and if necessary, the control is switched so as to reduce the image density and use the remaining developer efficiently.

Here, it is determined whether or not to set fnear, whether L is detected a predetermined number of times within a predetermined time, or whether the average value or the minimum value of the L level within a predetermined time is equal to or less than a predetermined value. There is a configuration that makes a judgment based on whether or not the developer is used. In this case, the predetermined time is set to be the first four rotations of the developing sleeve from when the developing device is driven to before the effect of the scattering of the developer appears. The scattering of the developer is affected by the rotation speed of the developing sleeve, and when the rotation speed is reduced to less than half, the scattering of the developer is sharply reduced, so that the driving speed of the developing device is reduced to less than half, and the output of the light receiving sensor at that time is reduced. Can also be determined. This result is replaced with the result of determination immediately after driving the developing device. The first developing device of the present embodiment has been described above, but the second, third, and fourth developing devices are also described according to the same flow, and perform the same processing. It is also possible to add a configuration for determining whether or not the developer has reached a level at which the developing operation cannot be continued from the output of the light receiving sensor when the developing device is being driven.

When the "fend" flag is set, the driving of the developing device is stopped in a main flow (not shown) in order to avoid damaging the surface of the developing device by rotating the developing sleeve with the developer being empty. Is controlled as described above, and at the same time, a display requesting replenishment of the developer is performed. Also, when inputting directly to an AD converter without using a comparator, the flow can be exactly the same, but since the voltage level for receiving light can be set freely,
Finer control is possible. Furthermore, this embodiment is
Although the light receiving sensor is set to L when receiving light, a circuit configuration to be H when receiving light is also possible. Further, the above embodiment is applied to a color printer,
Since the copying machine has a configuration in which a scanner for reading a document is added to a printer, the above technique can be applied to the copying machine as it is. Furthermore, since the above technology is configured to detect when not affected by the scattering of powder,
If the device is such that the powder contained in the container is gradually reduced, the remaining amount or presence or absence of the powder can be detected without being limited to the toner.

[0031]

As described above, the electrophotographic apparatus of the present invention has the following effects. The electrophotographic apparatus according to claim 1 is provided with a light emitting unit and a light receiving sensor at positions facing each other via the developing device, and detects light from the light emitting unit through a transmission window provided in the developing device with the light receiving sensor. By determining the amount of the developer from the AC component of the output of the light receiving sensor, the presence or absence or the remaining amount of the developer can be realized at a low cost with a simple configuration. In the electrophotographic apparatus according to the second aspect, the light-shielding means is also used as a gear and an agitator which are indispensable to the developing device, and the light-shielding means is provided in an optical path for determining the presence or absence or remaining amount of the developer. The presence or absence or remaining amount of the agent can be detected at low cost by a small device with a simple configuration. The electrophotographic apparatus according to claim 3 has a configuration in which a resistor is inserted between the light receiving sensor and the power supply, the resistor is connected to the amplifier with a capacitor, and the output of the amplifier is connected to the input port of the microcomputer. Therefore, a small and highly reliable device can be provided at low cost. The electrophotographic apparatus according to claim 4 has a simple configuration in which a resistor is inserted between the light receiving sensor and the power supply, the resistor is connected to the amplifier with a capacitor, and the output of the amplifier is connected to the A / D input of the microcomputer. It is possible to provide a small and highly reliable device that can accurately detect the magnitude of the AC component and accurately determine the presence or absence or the remaining amount of the developer at a low cost. The electrophotographic apparatus according to claim 5,
By detecting the AC component and the DC component of the output of the light receiving sensor, it is possible to provide at a low cost a highly reliable small device capable of reliably determining the presence or absence or the remaining amount of the developer. The electrophotographic apparatus according to claim 6 detects the output of the light receiving sensor immediately after the rotation of the developing device is started and is not affected by the scattering of the developer. A highly reliable small device capable of accurately detecting the remaining amount can be provided at low cost.
8. The electrophotographic apparatus according to claim 7, wherein a low-cost component having a low light-emission output and a low-cost component having a low light-receiving sensitivity are provided by reducing the stirring speed of the developer during driving of the developing device to suppress the scattering of the developer. And a highly reliable device capable of accurately detecting the presence or absence or the remaining amount of the developer can be provided at low cost. The electrophotographic apparatus according to claim 8 prepares for the replacement of the developer by displaying the near end of the developer using a set of detection means, and displays the end of the developer to determine the prohibition of use of the electrophotographic apparatus. In addition, it is possible to provide an easy-to-use and highly reliable device that can prevent the developing device from being damaged. The electrophotographic apparatus according to the ninth aspect has a basic configuration including a general-purpose LED, a phototransistor, and a general-purpose operational amplifier in which a capacitor is coupled, and has a simple configuration in which a switch element is connected in parallel to an AC-coupling capacitor. A high and small device can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a color laser printer which is an embodiment of the electrophotographic apparatus of the present invention.

FIG. 2 is a diagram showing a light emitting unit used in the color laser printer shown in FIG. 1 and a circuit related thereto.

FIG. 3 is a diagram showing an AC amplifier circuit used in another embodiment of the electrophotographic apparatus of the present invention.

FIG. 4 is a schematic diagram showing an agitator driving gear used in the color laser printer shown in FIG. 1;

FIG. 5 is a schematic sectional view showing an agitator used in the color laser printer shown in FIG.

FIG. 6 illustrates a light emitting unit in a state where a developing device used in the color laser printer shown in FIG. 1 is fixed at a developing position.
FIG. 3 is a schematic partial cross-sectional view illustrating a positional relationship among a light receiving sensor, a transmission window, and an agitator.

FIG. 7 is a diagram illustrating a circuit configured to switch between AC amplification and DC amplification in the electrophotographic apparatus of the present invention.

8 is a diagram showing a collector waveform of a phototransistor in a state where a developer having a high pigment concentration is used in the color laser printer shown in FIG. 1 and the developer is sufficiently stirred.

9 shows a collector waveform of a phototransistor when a developer having a low pigment concentration is used or when the developer is almost empty using a developer having a high pigment concentration in the color laser printer shown in FIG. FIG.

10 is a diagram showing a collector waveform of a phototransistor immediately after driving a developing device using a developer having a high pigment concentration in the color laser printer shown in FIG. 1;

11 shows a subroutine for judging the near end of the developer in the color laser printer shown in FIG. 1, a subroutine for judging the end, and a subroutine for judging the end of the developer in another embodiment of the present invention. FIG. 3 is a schematic block diagram showing

FIG. 12 is a block diagram showing an outline of electrical components of the color laser printer shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st developing device 2 2nd developing device 3 3rd developing device 4 4th developing device 5a, 5b, 5c, 5d Transmission window 6a, 6b, 6c, 6d Developing sleeve 7a, 7b, 7c, 7d, 9a, 9b, 9c, 9d, 1
0a, 10b, 10c, 10d, 12a, 12b, 12
c, 12d Gears 8a, 8b, 8c, 8d, 11a, 11b, 11c, 1
1d Transmission Gear 13 First Cam 14 Second Cam 15 Third Cam 16 Fourth Cam 17 Drive Roller 18 Follower Roller 19 Laser Light 20 Photoconductor Belt 21 Scorotron Charger 22 Transfer Belt 23 Transfer Roller 24 Cleaning Roller 25 Paper Transfer Roller 26 Paper Transport Roller 27 Tension Roller 30 Fixing Device 40, 41 Plate 42 Shaft 43 Mylar Sheet 44 Agitator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA04 DA32 DD02 DD07 DE02 EA06 EC19 ED10 EF09 GA47 GB03 2H077 AB04 AD02 AD06 AD35 BA09 DA16 DA42 DA64 DB01 DB10 GA13

Claims (9)

[Claims] 1. A photoreceptor on which an electrostatic latent image is formed in accordance with color-coded print data, and a pair of transmissive windows at opposing positions on both side surfaces, in which developers of different colors are filled. A developing sleeve that carries a developer on the surface thereof; and a developing sleeve driving unit that rotationally drives the developing sleeve; a plurality of detachable developing devices that develop an electrostatic latent image on the photoconductor; A light emitting unit disposed opposite to the pair of transmission windows via a developing device, a light receiving sensor for detecting light from the light emitting unit, and a developing device of a corresponding color to the photoconductor at the start of development. An electrophotographic apparatus having a developing device fixed to an adjacent developing position and separated from the photoreceptor after development is completed, wherein the developing sleeve driving unit and the light emitting unit; Sen And a light-shielding unit that moves between the developing sleeve driving unit and the light receiving sensor in synchronization with the rotation of the developing sleeve. Alternatively, an electrophotographic apparatus including a developer amount determining unit for determining a remaining amount. 2. The light-shielding means is a gear or an agitator provided so that the transmission window is disposed within a radius of rotation and having at least one window through which light is transmitted. The electrophotographic apparatus according to claim 1, wherein the light or the light to the transmission window is periodically shielded in synchronization with the developing sleeve. 3. The light emitting means is an LED, the light receiving sensor is a phototransistor, an emitter of the phototransistor is connected to GND, a collector of the phototransistor is connected to a power supply, and the emitter or the collector is connected to the power supply. 3. The electronic device according to claim 1, wherein a resistor is connected in series, one end of the resistor is connected to an amplifier via a capacitor, and an output of the amplifier is connected to an input port of a microcomputer. Photo equipment. 4. The light-emitting means is an LED, the light-receiving sensor is a phototransistor, an emitter of the phototransistor is connected to GND, a collector of the phototransistor is connected to a power supply, and the emitter or the collector is connected to the power supply. 3. The device according to claim 1, wherein a resistor is connected in series, one end of the resistor is connected to an amplifier via a capacitor, and an output of the amplifier is connected to an A / D conversion input of a microcomputer. Electrophotographic equipment. 5. A photoreceptor on which an electrostatic latent image is formed in accordance with color-coded print data, and a pair of transmissive windows at opposing positions on both side surfaces, in which developers of different colors are filled. A developing sleeve that carries a developer on the surface thereof; and a developing sleeve driving unit that rotationally drives the developing sleeve; a plurality of detachable developing devices that develop an electrostatic latent image on the photoconductor; A light emitting unit disposed opposite to the pair of transmission windows via a developing device, a light receiving sensor for detecting light from the light emitting unit, and a developing device of a corresponding color to the photoconductor at the start of development. An electrophotographic apparatus having a developing device fixed to an adjacent developing position and separated from the photoreceptor after development is completed, wherein the developing sleeve driving unit and the light emitting unit; Sen And a light-shielding unit that moves between the developing sleeve driving unit and the light receiving sensor in synchronization with the rotation of the developing sleeve, and a unit that detects a DC component of the output of the light receiving sensor. An electrophotographic apparatus comprising: a developer amount determining unit configured to determine presence / absence or remaining amount of a developer based on outputs of an AC component and a DC component of the light receiving sensor. 6. The developer amount determining means determines whether or not the DC component of the output of the light receiving sensor is present or not during the rotation of the developing sleeve up to four times after the start of driving of the developing sleeve. The electrophotographic apparatus according to claim 5, wherein the presence or absence or remaining amount of the agent is determined. 7. The developing device further includes a developing sleeve deceleration unit that reduces a rotation speed of the developing sleeve to half or less, and the developer amount determining unit rotates the developing sleeve by the developing sleeve deceleration unit. 6. The electrophotographic apparatus according to claim 5, wherein after the speed is reduced, the presence or absence or the remaining amount of the developer is determined based on the presence or absence or magnitude of the DC component of the light receiving sensor. 8. The developer amount judging means includes: first developer amount judging means for detecting the presence or absence or magnitude of an AC component of the output of the light receiving sensor; and presence or absence or magnitude of a DC component of the output of the light receiving sensor. The first developer amount determination means indicates that the end of the developer amount is near, and the second developer amount determination means detects that the end of the developer amount is near. 8. The electrophotographic apparatus according to claim 5, wherein the absence of the developing device is displayed, and the prohibition of use of the developing device is determined. 9. The light emitting means is an LED, the light receiving sensor is a phototransistor, an emitter of the phototransistor is connected to GND, a collector of the phototransistor is connected to a power supply, and the emitter or the collector is connected to the power supply. A resistor is connected in series, the other end of the resistor is connected to one end of a capacitor, the other end of the capacitor is connected to an inverting input of an operational amplifier, and a switch element is connected in parallel with the capacitor. A resistor is arranged in series, connected between a power supply and GND, a connection point of the two resistors is connected to a non-inverting input of the operational amplifier, and an output of the operational amplifier is connected to an input port of a microcomputer or an A / D input. 9. The electrophotographic apparatus according to claim 5, wherein the electrophotographic apparatus is connected to a device.