JPS627070A - Toner residual detector - Google Patents

Abstract

PURPOSE:To detect toner residual by discriminating the reduction of toner in a toner feeding means for detecting the toner density of a two-component developer stored in a developing unit and feeding toner less the a prescribed volume when the number of times of feeding by the toner feeding means exceeds a reference value. CONSTITUTION:The developing unit 7 executes development by using the two- component developer consisting of toner and carrier and the developer is carried to a sliding part with a photosensitive body 2 by a magnetic roller 21. A magnetic sensor 23 is fitted to the side wall of the developing unit 7 so that its detecting head 24 is exposed into the developing unit 7. The detected toner density is supplied to a microcomputer through an A/D conversion circuit. The computer compares the toner density with a set-up reference level and drives a solenoid in accordance with the compared result to feed the constant quantity of toner to the developing unit 7. The number of times of toner feeding is calculated, and when the calculated value exceeds a reference value, the reduction of toner in a hopper 25 less than the prescribed volume is discriminated. Thus, the toner residual can be precisely detected.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a toner remaining amount detection device for detecting the remaining amount of toner in a toner replenishing means that replenishes toner to a developing device in an image forming apparatus such as a copying machine. Regarding.

[Technical background of invention! ] Generally, for example, in a copying machine, a developing device is often used that develops an electrostatic latent image on a photoreceptor using a magnetic brush method using a two-component developer consisting of toner and carrier. In a copying machine using such a developing device, a density detector detects the toner concentration of the developer contained in the developing device, and a toner replenishing means is operated according to the detection result to replenish toner. The toner concentration in the developer is controlled to a constant value.

Further, when the amount of replenishing toner in the toner replenishing means falls below a predetermined amount (toner empty), this is also detected. That is, as the amount of toner decreases, an actuator installed inside a toner hopper that stores replenishment toner approaches a reed switch installed on the side of the toner hopper, and a magnet attached to the tip of the actuator turns on the reed switch. As a result, the on signal causes the toner empty indicator to light up and also stops the copying operation.

[Problems with the Background Art] However, in this conventional toner remaining amount detection method, the reed switch is turned on before the toner hopper is completely empty, so it is difficult to accurately determine the toner remaining amount in the toner hopper. In addition, since a mechanical detection means is used, malfunctions are likely to occur (and it is difficult to simplify the shape of the toner hopper when converting it into a cartridge, resulting in high costs). There was also the problem that it became

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to more accurately detect the remaining amount of toner in the toner replenishing means, and to simplify the structure of the toner replenishing means. It is an object of the present invention to provide a toner remaining amount detection device that can be used to reduce costs.

[Summary of the Invention] In order to achieve the above object, the present invention counts the number of toner replenishments by a toner replenishing means, compares the counted value with a preset reference value, and determines that the counted value exceeds the reference value. The device is configured to determine when the amount of toner in the toner replenishing means has fallen below a predetermined amount.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 6 shows a copying machine as an example of an image forming apparatus according to the present invention. That is, 1 is a housing, and a photosensitive drum 2 that rotates in the direction of arrow a in the figure is provided approximately at the center of the housing. Further, in the upper part of the housing 1, a document table 3 for supporting a document is provided so as to be able to reciprocate in the direction indicated by the arrow in the figure. By moving the document table 3 in synchronization with the rotation of the photoreceptor drum 2, the light emitted from the exposure lamp 4 is reflected by the document on the document table 3, and the reflected light is transmitted through convergent light transmission. An image is formed on the photoreceptor drum 2 by the body 5, and is reflected on the photoreceptor drum 2 as an inverted image of the document. At this time, by charging the surface of the photoreceptor drum 2 with the charging device 6, an inverted image of the original is formed on the photoreceptor drum 2 as an electrostatic latent image, and this electrostatic latent image is developed. It is configured to be visualized by applying toner with a container 7.

On the other hand, a paper feed device 8 is provided at a lower portion of the housing 1 to supply paper to the lower part of the photoreceptor drum 2 (image transfer section 14). The paper feed device 8 includes a paper feed cassette 9 which is detachably attached to the left side of the housing 1 and stores a plurality of sheets of paper, and a manual feed cassette 9 which is protruded from the right side of the housing 1 and is used to feed paper manually. 1 sheet of paper from the paper feed table 10 and the paper feed cassette 9
It has a paper feed roller 511 that feeds out sheets one by one, and a conveyance roller 12 that conveys the paper fed out by the paper feed roller 511. At the same time as stopping the
The configuration includes a registration roller 13 that corrects the inclination of the leading edge of the paper and sends the paper to the image transfer unit 14 at a timing such that the leading edge of the paper and the leading edge of the toner image on the photoreceptor drum 2 coincide. There is.

The paper conveyed by the registration row 513 is sent to the image transfer section 14. The paper sent to the image transfer unit 14 comes into close contact with the surface of the photoreceptor drum 2 at the transfer charger 15, and the toner image on the photoreceptor drum 2 is then charged by the charger 15. is transcribed. After the transfer, the photosensitive drum 2 is configured so that residual toner on the surface thereof is removed by a cleaner 16 and the photosensitive drum 2 returns to its initial state. On the other hand, the paper after transfer is transferred to the transport roller 1.
7 to a heat roller 18 as a fixing device,
By passing through the fixing roller 18, the transferred image is heated and fixed. Then, the paper after fixing is transferred to the paper ejection roller 1.
9 so that the paper is discharged onto a tray 20 outside the housing 1.

The developing device 7 performs development using a two-component developer consisting of toner and carrier, and by forming a magnetic brush of the developer on the surface, the developer is applied to the area to be developed, that is, the photosensitive drum 2. A magnetic roller (
(developing roller) 21. In addition, 22 is the developing device 7
This is a developer stirring body that stirs the developer inside. A magnetic sensor 23 serving as a toner concentration detection means is mounted on the side wall of the developing device 7 with its detection head 24 exposed inside the developing device 7. is detected by changes in the magnetic permeability of the developer. Further, a toner hopper 25 containing toner for replenishment is provided above the developing unit 7, and by rotating a toner replenishment row 526 provided at the bottom of the toner hopper 25, a certain amount of toner in the toner hopper 25 is released. The developer is replenished into the developing device 7 one by one. The toner supply roller 26 is rotatably driven by a solenoid (not shown) via a rotation mechanism (not shown).

FIG. 5 shows the operation panel of the copying machine configured as described above.
1. A numeric keypad 32 for setting the number of copies, etc., a number display section 33 for displaying the number of copies, a remaining toner amount display section 34 for displaying the amount of toner remaining in the toner hopper 25, and a clear button for clearing the number of times of toner replenishment, which will be described later. A switch (key switch) 40, a status display section 35 that displays the operating status of each part, a density setting section 36 that sets the copy density, a magnification setting section 37 that selects and sets a specific predetermined copy magnification, and an arbitrary copying section. A zoom key 38 for setting the magnification, a magnification display section 39 for displaying the set magnification, and the like are provided. The toner remaining amount display unit 34 is constituted by, for example, a plurality of light emitting diodes L1 to LN, and displays the remaining amount of toner by the number of light emitting diodes L1 to LN-1 lit, and also displays toner empty by the light emitting diode LN. It is now possible to do this. Note that among the light emitting diodes L1 to LN, only the light emitting diode LN emits light in a different color from the other light emitting diodes. That is, for example, when the light emitting diodes 11 to LN-1 light up sequentially in that order as the remaining amount of toner decreases, and the last light emitting diode LN with a different emission color lights up, it is determined that the toner in the toner hopper 25 has run out ( A message indicating that the amount has fallen below a predetermined amount (toner empty) is displayed to prompt the user to replenish toner to the toner hopper 25.

FIG. 1 shows the control circuit. That is, the magnetic sensor 23 includes a detection head 24 that includes an adjustment coil and a detection coil that come into contact with the developer in the developing device 7 and detect the magnetic permeability of the developer, and a detection head 24 that drives the detection head 24 and also serves as a reference. An oscillator 41 that outputs a phase signal, an amplifier 42 that amplifies the minute output signal from the detection head 24, and a comparison of the phase difference between the detection signal amplified by the amplifier 42 and the reference phase signal output from the oscillator 41. The phase comparator 43 includes a low-pass filter 44 that shapes the waveform of the signal output from the phase comparator 43.

The characteristics of the output voltage with respect to the toner concentration of the magnetic sensor 23 are shown in FIG. 2, and the output voltage increases as the toner concentration becomes thinner. The output voltage of the magnetic sensor 23 is an 8-bit A/
The signal is supplied to the D conversion circuit 45. This A/D conversion circuit 45
starts the conversion operation when a conversion command signal is supplied from the microcomputer (hereinafter simply referred to as microcomputer) 46 that controls the entire copying machine, converts the input analog signal into digital data, and performs multi-step processing. The data is supplied to the microcomputer 46 as toner density data. Also, microcomputer 46
The clear switch 40 and the auto toner set mode switch 47 are connected to the clear switch 40, and by turning on the switch 47, the auto toner set mode is set. Further, a solenoid drive circuit 48 is connected to the microcomputer 46, and this drive circuit 48 drives a toner replenishment solenoid 49.

The toner replenishment solenoid 49 is for rotationally driving the toner replenishment row 526. Further, a ROM (read only memory) 50 and a RAM (random access memory) 51 for storing data are connected to the microcomputer 46.
is backed up by a backup power source 52 such as a battery. The ROM 50 stores fixed data D1 to DN-1 (DI<D2<03,
...<0N-1) is stored. Further, the RAM 51 stores reference data A and a count value C of the number of times of toner replenishment, which will be described later. Furthermore, microcomputer 46
The remaining toner amount display section 3-4 is connected to.

Next, the operation in the above configuration will be explained. First, the operation of the main program will be explained with reference to the flowchart shown in FIG. Now, when the copy key 31 is turned on, the process proceeds to step A1, where it is determined whether the clear switch 40 is on, and if it is not, the process proceeds to step A2.

In step A2, it is determined whether the mode is normal copy mode or auto toner set mode based on the state of the switch 47, and if it is the normal copy mode (if the switch 47 is in the off state).
Proceed to step A3. In step A3, by setting an external interrupt timer, external interrupts are enabled, for example, at intervals of 10 m5ec, and in step A4 of normal copy control.
Proceed to.

Note that if interrupts are enabled using the external interrupt timer above,
An interrupt program for automatic toner detection mode, which will be described later, is executed. On the other hand, in step A2 above,
If it is the auto toner set mode (if the switch 47 is on), the process proceeds to step A5, where a timer is set for, for example, 3 minutes to stir the developer, and the process proceeds to step 86.

In step A6, it is determined whether 3 minutes have elapsed, and 3 minutes have elapsed.
When the minute has elapsed, the process advances to step A7. In step A7, for example, a 350m5ec timer is set, and the process proceeds to step 88. In step 88, it is determined whether 350 m5 ec has elapsed or not, and when 350 m5 ec has elapsed, the process advances to step A9.

In step A9, the microcomputer 46
A/D conversion is started by supplying a conversion command signal to step AIO.

In step AIO, the toner density data obtained by the A/D conversion is stored in the RAM 51 as reference data A, and the process proceeds to step A11. In step A11, it is determined whether or not the mode is auto toner set mode. If the mode is not the auto toner set mode (if the switch 47 is off), the process returns to step A3, and if the mode is the auto toner set mode, the process returns to step A7. Go back and repeat the same operation as above. In this case, the reference data stored in the RAM 51 will be sequentially rewritten with new data. After repeating this a predetermined number of times every 350 m5ec, the switch 47 is turned off to end the auto 1-nurset mode operation and the reference data A is stored in the RAM 51. In this mode, an initial developer serving as a reference is stored in the developing device 7 in advance, and its 1 to 4 densities are detected as described above and the reference data A is obtained.
That is.

Next, the operation of the interrupt program will be explained with reference to the flowchart shown in FIG. As described above, this operation is performed every time an interrupt is permitted by the external interrupt timer at intervals of 10m5eC. If the interrupt is permitted, the process proceeds to step B1 to start A/D conversion, and the process proceeds to step B2. In step B2, the reference data A and the number of toner replenishments C are read from the RAM 51, and
Proceed to step B3. In step B3, the toner density data B obtained by the A/D conversion in step B1 is compared with the reference data A read from the RAM 51, and when A>8 (that is, when the toner density is high), step B4 is performed. move on. In step B4, the solenoid 49 is turned off and the process returns to the main program. In step B3 above, if A≦゛B (that is, the toner density is low,
(or when the concentration is the standard) proceed to step B51. In step 851, the fixed data D1 in the ROM 50 is compared with the number of toner replenishments C read out from the RAM 51, and if D1≧C, the process advances to step B61. In step B61, the light emitting diode L1 is turned on, and the process proceeds to step B7.

In step B7, the solenoid 49 is turned on to replenish toner, and the process proceeds to step B8. In step B8, the number of toner replenishments is counted, and the process proceeds to step B9. In step B9, the number of times C of toner replenishment counted in step B8 is stored in the RAM 51, and the process returns to the main program.

In step 851, if Dl<C, the process advances to step B52. In step B52, the fixed data D2 in the ROM 50 is compared with the number of toner replenishments C read out from the RAM 51, and if D2≧C, the process advances to step B62. In step B62, the light emitting diode L2 is turned on, and the process proceeds to step B7, whereupon similar operations are performed. In step B52, if D2<C, the process proceeds in the same manner to steps 853 to 85N-1 and steps 861 to 86N-1, and the fixed data D3.・
...Comparison is made in the same way as for DN-1, and light emitting diode L3. ...Turn on LN-1 and solenoid 49. Therefore, as the amount of toner in the toner hopper 25 decreases in accordance with the number of toner replenishment operations, the number of light-emitting diodes L1 to LN-1 of the remaining toner indicator 34 increases sequentially to prevent remaining toner. It will be displayed. Then, in step 85N-1, DN-1<
When it reaches C, it is determined that the toner is empty, and the process proceeds to step 810. In step B10, the light emitting diode LN is turned on and the copying operation is stopped.

Return to main program. By lighting the light emitting diode LN, toner empty (toner in the toner hopper 25 has fallen below a predetermined amount) is displayed, and the user is prompted to replenish the toner hopper 25 with toner.

On the other hand, if the clear switch 40 is turned on in step AI (see FIG. 3), step A12
Proceed to. In step A12, the number of times C of toner replenishment stored in the RAM 51 is cleared to "0", and the process proceeds to step A2. That is, for example, when the toner hopper 25 is removed and replaced with a new toner hopper containing a certain amount of toner, the clear switch 40 is turned on to clear the toner replenishment count C in the RAM 51 to "0".

In this way, the number of times that toner is replenished from the toner hopper to the developing device is counted, and the counted value is compared with a preset reference value, and when the counted value exceeds the reference value, the toner in the toner hopper is less than the predetermined amount. This is to determine whether the toner is empty (toner empty). As a result, compared to conventional mechanical means, it is possible to more accurately detect when the toner in the toner hopper is empty, and it also allows for greater flexibility in the shape of the toner hopper when converting the toner hopper into a cartridge. This increases the toner hopper structure and reduces costs.

In the above embodiment, a ROM was provided separately from the microcomputer and fixed data was stored in this ROM, but the ROM may not be provided and the fixed data may be stored in a ROM within the microcomputer.

Further, although the case has been described in which the toner remaining amount display section is configured with a plurality of light emitting diodes, for example, a liquid crystal display element or the like may be used.

Further, in the above embodiment, a case has been described in which the amount of toner remaining in a toner replenishing means that replenishes toner to a developing device in a copying machine is detected, but the present invention is not limited to this, and the present invention is not limited to this. In an image forming apparatus (such as a laser printer or an electronic printer) that is equipped with a developing device that forms an image using a two-component developer, the amount of toner remaining in a toner replenishing means that replenishes toner to the developing device is detected. If applicable, it can be applied.

[Effects of the Invention] As detailed above, according to the present invention, the amount of toner remaining in the toner replenishing means can be detected more accurately, the structure of the toner replenishing means can be simplified, and the cost can be reduced. However, a detection device can be provided.

[Brief explanation of the drawing]

The figures are for explaining one embodiment of the present invention. Figure 1 is a configuration diagram of the control circuit, Figure 2 is a diagram showing the characteristics of the output voltage with respect to the toner concentration of the magnetic sensor, and Figure 3 is the main program. 4 is a flowchart for explaining the operation of the interrupt program, FIG. 5 is a configuration diagram of the operation panel, and FIG. 6 is a side view schematically showing the configuration of the copying machine. be. 2...Photosensitive drum, 7...Developer, 23...Magnetic sensor, 25...Toner hopper, 26...Toner replenishment roller , 34...
... Toner remaining amount display section, 40 ... Clear switch, 45 ... A/D conversion circuit, 46 ...
...Microcomputer, 48...Solenoid drive circuit, 49...Solenoid for toner replenishment, 5o...
...ROM.

Claims (7)

[Claims] (1) In an image forming apparatus that performs image formation using a developing device equipped with a developer conveying means for conveying a two-component developer consisting of toner and carrier to a developing area, a developing device housed in the developing device a toner concentration detection means for detecting the toner concentration of the toner; a comparison means for comparing the output of the toner concentration detection means with a preset reference level; A toner replenishing means for replenishing toner, a counting means for counting the number of times the toner is replenished by the toner replenishing means, a storage means for storing the count value of the counting means, and a count value stored in the storage means is set in advance. 2. A remaining toner amount detecting device comprising: a determining means for comparing the counted value with a reference value and determining that the amount of toner in the toner replenishing means has fallen below a predetermined amount when the counted value exceeds the reference value. (2) The remaining toner amount detecting device according to claim 1, wherein the contents of the storage means can be cleared as necessary. (3) The remaining toner amount detecting device according to claim 2, wherein the clearing is performed by a clear switch provided on an operation panel of the image forming apparatus. (4) The remaining toner amount detecting device according to claim 1, wherein the storage means is a nonvolatile memory. (5) When the determining means determines that the amount of toner is below a predetermined amount, a message to that effect is displayed and the operation of the image forming apparatus is stopped. The remaining toner amount detection device described. (6) The toner concentration detection means includes a magnetic sensor that detects the toner concentration of the developer by magnetically detecting changes in the magnetic permeability of the developer and converts it into an analog electrical signal;
2. The remaining toner amount detecting device according to claim 1, further comprising converting means for obtaining multi-level toner density data by converting the output signal of the magnetic sensor into digital data. (7) The remaining toner amount detection device according to claim 1, wherein the image forming device is a copying machine.