JPH0678000B2 - Life display of cleaning device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an electrophotographic printer that prints an image in dots using an electrophotographic process, and more specifically, to predict the life of a cleaning device provided in the printer. Life display device.

[Prior art]

The electrophotographic printer forms dots of a toner image based on image data on an image carrier such as a photosensitive drum,
It has a process means for transferring this dot image onto a transfer paper. When the transfer is performed, not all the toner is transferred to the transfer paper, and a part of the toner remains on the image carrier. Therefore, the residual toner is removed and collected by the cleaning device.
In such an apparatus, a toner storage section is provided in the cleaning apparatus to store the collected waste toner therein, and therefore it is required to detect the amount of the waste toner, and various detection apparatuses have been proposed. ing.

For example, since it is difficult to directly detect the amount of waste toner, it has been proposed to count the number of printed transfer sheets and estimate the approximate amount of waste toner based on this count. There is also known a device in which the degree of waste toner accumulation in the waste toner storage portion is monitored using a photosensor or the like.

[Problems of conventional technology]

However, in the former detection device that counts the number of transfer sheets, the amount of toner used for printing on the transfer sheet, that is, the number of dots for each transfer sheet differs depending on the type of image, and therefore the amount of waste toner for each transfer sheet varies. Variations, the amount of waste toner cannot be detected accurately. In particular, in the case of an apparatus in which the photosensitive drum and a cleaning device are integrated to form an image forming unit and which is detachably incorporated into the apparatus main body, the life time of the photosensitive drum and the time when the waste toner storage section is filled with the waste toner are And when this lifespan comes,
It is desirable to inform the user that it is time to replace the image forming unit.

However, in the former detection device described above, since the amount of waste toner cannot be accurately detected, the life of the cleaning device is earlier than the life of the photosensitive drum, and waste toner may overflow from the waste toner storage section. It happens. In order to prevent such a situation, it is necessary to design the waste toner storage portion to have a large capacity with a large margin. As a result, the size of the cleaning device becomes large, and the size of the entire printer becomes large.

Further, if the latter is a detection device using a photo sensor,
The photo sensor is easily contaminated by toner or other dust,
It is difficult to accurately detect the amount of waste toner. Therefore, even if this detecting device is used in the above-mentioned image forming unit, the same problem as described above still occurs.

[Object of the Invention]

In view of the above problems, the present invention can calculate and display how many more sheets can be printed from the capacity of the toner storage section of the cleaning section and the number of print dots up to that time, and thereby display the remaining life of the cleaning section. It is an object of the present invention to provide a life display device for a cleaning device capable of displaying the.

[Summary of Invention]

In order to achieve the above object, the present invention comprises an image carrier, a process means for forming an image on the image carrier, and a cleaning means for removing and collecting the toner remaining on the image carrier after the image formation. In the electrophotographic dot printer having the first counter means for accumulatively counting the number of black dots printed, the second counter means for counting the number of black dots for each printing of one sheet, and the life for storing the life capacity of the cleaning means. Storage means, subtraction means for subtracting the count value of the first counter means from the stored value of the life storage means, division means for dividing the subtraction value by the count value of the second counter means, and the division Display means for displaying the remaining life of the cleaning means based on the value is provided.

Example of Invention

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention.
In the figure, the photosensitive surface of the photosensitive drum 1 which is an image carrier.
1a is previously given a uniform charge by the charger 2. The optical writing unit 3 includes a liquid crystal optical shutter (not shown) and the like, and is driven by the recording control unit 4 to perform optical writing with dots on the photosensitive surface 1a to form an electrostatic latent image. The electrostatic latent image formed in this manner is developed with toner in the developing device 5 and visualized. Further, the toner image of this dot configuration is transferred to the transfer device 6.
Then, it is transferred from the cassette 8 by the paper feed roll 7 and transferred to the transfer paper which is carried in by the standby roll 9 at the same timing. After the transfer paper is separated by the separator 10, the fixing device 11
It is carried out of the machine by the paper discharge roll 12 via. on the other hand,
Since the toner not completely transferred by the transfer device 6 remains on the photosensitive surface 1a, the electric charge of the toner is neutralized by the static eliminator 13 and the residual toner is collected by the cleaning unit 14. The collected toner is used as waste toner, and the cleaning unit 14
It is stored in the waste toner storage portion 14a provided in the. After that, the eraser 15 removes charges from the photosensitive surface 1a, and the charger 2 applies uniform charges in preparation for another optical writing.

The charging device 2, the photoconductor drum 1, and the cleaning unit 14 described above constitute an integral image forming unit 18, which is detachably incorporated in the apparatus main body.

Further, as will be described later in detail, based on the signal output from the recording control unit 4, the number of black dots forming the image formed in the image forming process by the first counter circuit (hereinafter, black dot printing Number) is cumulatively counted. Further, the second counter circuit counts the number of black dots printed for each transfer sheet. Then, the life capacity determined in advance from the permissible amount of recovered toner of the cleaning unit is stored, and the cumulative black dot print number output from the first counter is subtracted from this life capacity. Further, by dividing the subtracted value by the black dot printing for each sheet output from the second counter unit, it is predicted how many more sheets can be printed, and the remaining printing sheet number is displayed to display the cleaning device. Display the life of.

Next, a specific configuration of the recording control unit 4 will be described. The recording control section 4 comprises the control circuit shown in FIG. 4 and the control circuit shown in FIG. First, the control circuit of FIG. 4 will be described. The interface unit 19 receives various kinds of information such as a clock signal and a write enable signal and a recording data signal S ₁ from an external host CPU. The timing control unit 20 controls the writing cycle of the liquid crystal optical shutter provided in the optical writing unit 3 and the timing of receiving the recording data signal S ₁ ,
The recording data signal S ₁ input to the interface section 19 is converted into a serial recording data signal S ₂ and output to the shift register 21 shown in FIG. Further, the output of the oscillator 22 is input to the timing signal generator 23, and the transfer clock signal S ₃ ,
The latch signal S ₄ and the drive pattern signal S ₅ are created. The transfer clock signal S ₃ and the latch signal S ₄ are transferred to the timing control unit 20.
5 is output to the shift register 21 and the data latch 24 shown in FIG. 5, respectively, and the drive pattern signal S ₅ is directly output from the timing signal generator 23 to the optical shutter drive circuit 25. Next, the control circuit shown in FIG. 5 will be described. By inputting the recording data signal S ₂ in synchronization with the transfer clock signal S ₃ , the shift register 21 holds n-bit recording data. This recording data is input to the data latch 24 by the latch signal S _4, is held as the recording data for one line, and the next recording data signal S ₂ is input to the shift register 21. Next, the recording data for one line held in the data latch 24 is input to the optical shutter drive circuit 25. And the recording data, by a single pattern signal selected from among a plurality of drive pattern signals S _5, the liquid crystal optical shutter 3a described above is driven.

When the liquid crystal optical shutter 3a is driven, an electrostatic latent image is formed by dots on the photosensitive surface 1a as described above, and the electrostatic latent image is visualized as a toner image by the developing device 5. After that, the toner image is transferred onto the transfer paper supplied from the cassette 8, and a part of the toner image is collected by the cleaning unit 14 as residual toner.

The basic idea for detecting the amount of waste toner will be described below with reference to specific examples.

First, the liquid crystal optical shutter 3a is, for example, 240 dots / inch
When printing with the resolution of, the number of dots printed per 1 mm is 9.45 dots / mm. Therefore, A4
When printing is performed on the entire surface of the size transfer paper (210 mm × 297 mm), the number of black dots printed is (210 × 9.45) × (297 × 9.
45) ≈ 5.57 million. However, in normal printing, approximately 5.5% of the paper area can be estimated to be the black print portion, so it can be considered that an average of 5.57 million × 0.055 ≈ 306000 black dots are printed.

Further, it is experimentally confirmed that the transfer rate when the toner image formed on the photosensitive surface 1a is transferred onto the transfer paper is generally about 80%, so the remaining about 20% of the toner is waste toner. Will be collected in the waste toner storage unit 14a. On the other hand, it has been experimentally confirmed that about 50 mg of toner is consumed when an A4 size image having about 5.5% of the black print portion is printed. Therefore, A4 size transfer paper 1
About 20% of the 50 mg toner, that is, 10 mg of toner is collected as waste toner every time printing is performed on a sheet. Therefore,
The number of printed black dots and the amount of waste toner correspond exactly to each other. For example, when about 306,000 black dots are counted, it can be accurately known that the amount of waste toner is 10 mg.

Therefore, if it is desired to match the time when the waste toner storage portion 14a is filled with the waste toner with the life time of the photosensitive drum 1, the volume of the waste toner storage portion 14a must be set in consideration of the life time. . Therefore, the life time above is set to A4
Converting to the number of prints of the size transfer paper, if it is 7,000,
It is sufficient to provide the waste toner storage portion 14a with a volume capable of storing a maximum of about 7,000 × 10 mg = 70 g of waste toner. Therefore, if the weight-volume ratio of the toner is 0.3 g / cm ³ , the volume is 70 /
0.3 ≈ 230 cm ³ can be set, but a safety factor of 300 cm
It should be about ³ volumes.

With the above settings, the total number of black dots printed until the above period is about 306000 × 7000≈2.2 billion from the above calculation. Therefore, the photosensitive drum 1 and the cleaning unit 14
The number of black dots printed is 22 after the image forming unit 18 is installed in the main body of the device.
It is the time when 100 million pieces are accumulated.

Next, FIG. 1 shows a specific circuit configuration of the present invention based on the above-described concept. In the figure, an AND circuit 26
The recording data signal S ₂ and the clock signal S ₆ shown in FIG. The recording data signal S ₂ includes
As shown in FIG. 2, black-and-white information for opening and closing the liquid crystal optical shutter 3a according to the white and black portions of the image to be printed is included as serial data. That is, H
The level portion corresponds to the black portion of the image, and the L level portion corresponds to the white portion. The clock signal S ₆ is composed of a pulse having a constant cycle in synchronization with the actual opening / closing timing of the liquid crystal optical shutter 3a, and one pulse of black or white printing is performed. Therefore, the AND circuit 26 outputs one pulse each time a black dot is printed.

Pulses output by the AND circuit 26 is led to 2 ¹¹ frequency divider 27, where it is 2 ¹¹ frequency-divided. That is, every time 2 ¹¹ (= 2048) pulses are output from the AND circuit 26, the output pulse of the 2 ¹¹ frequency divider circuit 27 completes one cycle.

The output signal of the 2 ¹¹ frequency dividing circuit 27 is sent to the first counter circuit 28 and the second counter circuit 29. First counter circuit
28 is a 2-digit composed of 21-digit flip-flops Q _{1 to} Q _21.
It is a decimal counter. Output signals of the 2 ¹¹ divider circuit 27 is inputted to the clock terminal of the first flip-flop Q _1, its output is input to the clock terminal of the succeeding flip-flop Q _2. Similarly, flip-flop Q _n (n = 0,1,2,
The output of ..., 19) is the flip-flop Q of the next stage.
Input to the clock terminal of _n-1 . Further, a constant voltage (V _DD ) is applied from the power supply to the J terminal and the K terminal of each flip-flop Q _{1 to} Q ₂₁ through the diode D ₁ . In such a first counter circuit 28, the pulse output from the 2 ¹¹ frequency divider 27 is counted up at the time of fall of the H L, and the falling of 2 ²⁰ th of the pulse 20 The output of the second flip-flop Q ₂₀ (not shown) falls. Due to this fall, the output of the final stage flip-flop Q ₂₁ is switched to the H level.

After all, by the 2 ¹¹ frequency divider 27 and the first counter circuit 28 is connected to a serial, can accumulate counts the pulses output from the AND circuit 26, the whole of these 2
Can count ³¹ (≈ 2.2 billion) pulses.

Therefore, since the number of pulses output from the AND circuit 26 corresponds to the number of black dot prints, the first counter circuit 28 can cumulatively count the number of black dot prints. This count value can be seen at the output of the final stage flip-flop Q ₂₁ , and as described above, the output of the AND circuit 26 is divided by 2 ^31, and the 2 ¹¹ divider circuit 27 divides it by 2 ^11. 2 so
It becomes a constant of ³¹ ÷ 2 ¹¹ = 1048576. This constant is the amount of waste toner that can be collected, that is, the number of dots that can be printed.
6 is equivalent to 70 million sheets of A4 size paper. Therefore, one sheet is about 150, and this constant is an image density constant for one transfer sheet. Further, the 2 ¹¹ frequency dividing circuit 27 and the first counter circuit 28 as a whole can count 2 ³¹ (≈2.2 billion) black dot print numbers. When 2 ³¹ pulses are output from the AND circuit 26, an H level signal is output from the final stage flip-flop Q _{21 of} the first counter circuit 28, and this H signal is output to the printer control circuit 17 as a life signal. Is output. The number of black dots printed by the first actuator circuit 28 is output to the subtraction circuit 30 via the bus line A. In this way, the first counter circuit 28 can count all the black dot print numbers formed by one image forming unit, and cumulatively count up to the constant 1048576 of the above-mentioned allowable amount of waste toner. You can

The second counter circuit 29 includes flip-flops Q ₂₂ to Q _32.
Is a 11-digit counter circuit in which
The basic configuration is the same as that of the first counter circuit 28 described above. The second counter circuit 29 is the first counter circuit.
28 and is driven by the same output of the 2 ¹¹ divider circuit 27, counts the number of print black dots by a signal outputted from the AND circuit 26. The output of the 2 ¹¹ divider circuit, when the standard print density was 5.5%, and 150 counts. Even if the maximum density is 55%, which is 10 times the standard density, the output of 150 × 10 = 1500 counts is output to the second counter circuit 29. Therefore, the second counter circuit 29 is sufficient if the count function of the 2 ¹¹ may be constituted by a 11-digit counter circuit. The reset terminal of each flip-flop of the second counter circuit 29 is reset by the clear signal A output from the printer control circuit 17. The clear signal A is output when the printing of one transfer sheet is completed. Therefore, the second counter circuit 29 is reset when the printing of one transfer sheet is completed, and counts the number of black dots printed for each transfer sheet. The number of black dots printed for one sheet of transfer paper counted by the second counter circuit 29 is output to the division circuit 31 through the bus line B. Thus, the first
The counter circuit 28 cumulatively counts the number of black dots printed, and the second counter circuit 29 counts the number of black dots printed for each transfer sheet.

The black dot print number cumulatively counted by the first counter circuit 28 is output to the subtraction circuit 30 as described above. The subtraction circuit 30 has a storage unit inside, and the above-mentioned number of printed black dots 2 ^{31 is set} to 2
^The constant 1048576 divided by ^11, that is, the life capacity is stored in the cleaning unit. Then, the number cumulatively counted by the first counter circuit 28 is subtracted from this number each time one sheet of transfer paper is printed, and the subtracted output S ₇ is output to the divider circuit 31. Therefore, the subtraction circuit 30 subtracts the cumulative number of prints made up to that time from the life print count, and the output is the remaining allowable black dot print count.

The division circuit 31 outputs the remaining allowable dot print count S ₇
Is divided by the number of black dots printed on one sheet of transfer paper output from the second counter circuit 29, and the output S ₈ is displayed on the display control circuit.
Output to 32. This means that the remaining allowable dot print number is divided by the dot print number of one transfer sheet that has just been printed, and therefore, the number of transfer sheets that can be printed is calculated. For example, the output of the first counter circuit 28 is 524288
If so, the waste toner capacity is 1/2 of the allowable amount because it is 1/2 of the above-mentioned constant 1048576. At this time, if the output of the second counter 29 is 200, which is higher than the standard density, the remaining number of transfer sheets that can be printed is (1048576 ÷ 52428).
8) ÷ 200 = 2600 sheets. In other words, if you continue printing at the same density, you can print about 2600 more sheets.

The signal S ₈ of the calculation result of the division circuit 31 is output to the display control circuit 32, and is displayed on the display 33 by driving the control circuit 32. The display unit 33 may be a numerical display using a 7-segment display element, a bar graph type analog display, or the like.

Further, the above-mentioned first counter circuit 28 includes the backup battery 34, and when the power supply V _D is cut off, the backup battery 34 automatically supplies power to the first counter circuit 28 through the diode D ₂ . As a result, the count value before the power was turned off is held in the first counter circuit 28. Therefore, if the power is next turned on and the printing operation is restarted, the count value thereafter is the same as the previous count value. Is added. Further, since the clear signal B is output when the image forming unit including the waste toner storage portion 14a is replaced, the count value of the first counter circuit 28 is zero when a new image forming unit is mounted. Since the second counter circuit 29 counts the number of black dots printed on one sheet of transfer paper, a backup battery is unnecessary. It is also possible to provide a function of blocking printing when the output of the subtraction circuit S ₇ becomes zero.

In the embodiment, the printer using the liquid crystal optical shutter has been described as an example, but the present invention is not limited to this, and can be used for a dot printer such as a laser, a light emitting diode, and a multi-stylus.

〔The invention's effect〕

As described above, according to the present invention, the number of black dot prints is cumulatively counted by the first counter circuit and subtracted from the previously stored life capacity of the cleaning unit, and the subtraction result is counted by the second counter circuit. Since it is divided by the number of black dots printed on each sheet of transfer paper, it is possible to predict how many more sheets will be printed. Therefore, by displaying the remaining number of printable sheets, it is possible to inform the user of the life of the cleaning unit. Further, since the number of remaining toner sheets can be displayed, it is possible to prevent a situation in which the collected toner overflows from the storage as in the past. Further, in consideration of such a situation, it is not necessary to allow the cleaning section to have a sufficient volume, so that the cleaning section can be downsized, and in turn, the entire printer can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a waveform diagram of an input signal for counting the number of black dot prints, FIG. 3 is a schematic configuration diagram of a printer, FIG. 4 and FIG. FIG. 3 is a block diagram of a recording control unit. 1 ... Photosensitive drum, 3 ... Optical writing section, 3a ... Liquid crystal optical shutter, 4 ... Recording control section, 5 ... Developing unit, 14 ... Cleaning section, 14a ... Waste toner storage section, 17 ... ... printer control circuit, 26 ... AND circuit, 27 ... 2 ¹¹ frequency divider circuit, 28 ... first counter circuit, 29 ... second counter circuit, 30 ... subtraction circuit, 31 ... division circuit.

Continuation of the front page (56) References JP-A-62-106477 (JP, A) JP-A-59-174366 (JP, A) Actually developed JP-A-62-76349 (JP, U)

Claims (1)

[Claims] 1. An electrophotographic dot printer having an image carrier, a process means for forming an image on the image carrier, and a cleaning means for removing and collecting toner remaining on the image carrier after image formation. , A first counter means for cumulatively counting the number of black dots printed, a second counter means for counting the number of black dots for each printing of one sheet, a life storage means for storing the life capacity of the cleaning means, and the life. Subtraction means for subtracting the count value of the first counter means from the storage value of the storage means, division means for dividing the subtraction value by the count value of the second counter means, and the cleaning means based on the division value. And a display means for displaying the remaining life of the cleaning device.