JP4822578B2 - Image forming apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and method for realizing an electrostatic latent image using an electrophotographic process. More specifically, a laser beam printer, a copier, a technique about the prediction of our Keru toner consumption facsimile.
[0002]
[Prior art]
Laser beam printers, copiers, and facsimile machines that perform image formation using an electrophotographic process use a two-component developer mainly composed of toner and a carrier. In the case of this method, the ratio of toner to carrier is extremely important for the image density. At the time of development, since the toner is consumed and the carrier is not consumed among the mixed toner and carrier, the ratio of the toner and the carrier changes. In an image forming apparatus using a two-component developer for this purpose, in order to accurately predict the toner consumption of the developer and to replenish the toner appropriately according to the prediction result, the toner and carrier inside the developing device are mixed. Equipped with a sensor to detect the ratio.
[0003]
FIG. 7 shows the overall configuration of a conventional image forming apparatus having a density control function using a sensor for detecting the mixing ratio of toner and carrier in the developing unit.
[0004]
The video controller 1 receives a signal written in a specific description language created by a host computer or the like (for example, a personal computer (hereinafter referred to as PC)), and creates a latent image by the laser driver 2 of the image forming apparatus main body. Signal processing is performed, and a signal is transmitted to the laser driver 2.
[0005]
The laser driver 2 converts an electrical signal into an optical signal by a light emitting element, for example, a laser diode (hereinafter referred to as LD), and a polygon mirror 3 attached to a polygon motor (not shown) that rotates at a high speed. The optical signal reflected by the polygon mirror 3 is irradiated on the surface of the photosensitive drum 6 by the reflection mirror 4.
[0006]
The photosensitive drum 6 is uniformly charged at a constant potential by the charger 5 in advance, and an electrostatic latent image is formed on the photosensitive drum 6 by changing the potential only at the light irradiation portion by receiving the light irradiation.
[0007]
The developing device 11 includes a developing roller 10 and a developer 12. According to the electrostatic latent image formed on the photosensitive drum 6, only the toner in the developer 12 adheres to the photosensitive drum 6 by the developing roller 10 and is embodied as an image. Is done. This image is transferred by a transfer device 8 to a recording member 20 typified by paper, an OHT film or the like.
[0008]
The recording member 20 is conveyed by the recording member conveying rollers 7 and 9. The recording member 20 to which the image has been transferred by the transfer device 8 is permanently fixed by a fixing device (not shown) by the conveyance roller 9 and conveyed outside the image forming apparatus.
[0009]
The developing device 11 is provided with a sensor 21 that detects the mixing ratio of the toner and carrier of the developer in the developing device, and is configured to detect the amount of toner consumed by the image forming operation.
[0010]
Further, the video controller 1 has a circuit for counting the ratio of the actual print image in the image size of the recording member 20 to be printed, that is, a laser lighting pixel number counting circuit for the total number of pixels, and this information is sequentially notified to the printer engine CPU 16. An output signal of the sensor 21 that detects the mixing ratio of the developer toner and the carrier is also connected to the CPU 16.
[0011]
The CPU 16 uses the information from the video controller 1 and the information from the sensor 21 that detects the mixing ratio of the toner and carrier of the developer so that the toner replenisher 14 replenishes the developer 11 with the motor driver board. A command signal is sent to 17.
[0012]
The motor driver board 17 is connected to the motor 18 and rotates according to a signal from the CPU 16. As the motor 18 rotates, the screw 13 connected to the motor 18 and the gear 19 rotates, and the toner in the toner supply container 14 is conveyed and supplied into the developing device 11. By such an operation, the concentration of the developer 12 in the developing device 11 is kept constant.
[0013]
[Problems to be solved by the invention]
However, in the above-described prior art, since the video controller counts the lighting ratio of the LD, in addition to bearing elements that must be controlled by the printer engine, the edge portion of the image is detected. Since smoothing processing for smoothing or processing for imparting gradation to the image is performed, the logic scale for the counting becomes large, which causes a cost increase.
[0014]
Furthermore, since the amount of information acquired by the printer engine CPU becomes enormous, the amount of processing work in the printer engine CPU increases, which also causes an increase in cost. There was.
[0015]
Accordingly, an object of the present invention is to enable processing related to prediction of toner consumption with an inexpensive configuration.
[0016]
[Means for Solving the Problems]
In order to achieve such an object, the present invention provides a laser beam light emitting element, laser control means for controlling light emission of the laser beam light emitting element based on an input signal, and light emission based on the laser beam light emitting element. An image forming apparatus comprising: an image carrier that forms an electrostatic latent image; and a developing unit that attaches toner to the electrostatic latent image on the image carrier and visualizes the image as a toner image. A video signal for controlling the light emission of the laser beam light emitting element, and counting means for counting the input video signal. The counting means is an image of one page for the input video signal. Without counting the video signal of all areas, the video signal is counted at a plurality of random locations in the entire image area of one page, Predict the toner consumption according to the ratio of the number of video signals that emit light from the laser beam emitting element in the count with respect to the number of samples of the video signal, or count with respect to the number of samples of the video signal in a plurality of locations. A process corresponding to a toner consumption amount corresponding to a ratio of the number of video signals to be emitted from the laser beam light emitting element is performed.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same location in each drawing also including the above-mentioned prior art.
[0030]
(Embodiment 1)
FIG. 1 shows the overall configuration of an image forming apparatus to which the present invention is applied. The video controller 1 receives a signal written in a specific description language created by a host computer or the like (PC), performs signal processing for creating a latent image by the laser driver 2 of the image forming apparatus body, and performs laser processing. A signal is transmitted to the driver 2.
[0031]
The laser driver 2 emits (lights) a laser beam with an LD based on an electric signal (video signal). The laser emitted by the LD is reflected by a polygon mirror 3 rotating at a high speed, that is, a polygon mirror 3 attached to a polygon motor (not shown). The reflected laser is irradiated onto the surface of the photosensitive drum 6 by the reflecting mirror 4.
[0032]
The photosensitive drum 6 is uniformly charged at a constant potential by the charger 5 in advance. When the photosensitive drum 6 is irradiated with light, the potential changes only at the light irradiation portion, thereby forming an electrostatic latent image on the photosensitive drum 6.
[0033]
The developing device 11 includes a developing roller 10 and a developer 12. According to the electrostatic latent image formed on the photosensitive drum 6, only the toner in the developer 12 adheres to the photosensitive drum 6 by the developing roller 10 and is embodied as an image. This image is transferred by the transfer unit 8 to a recording member 20 typified by paper, OHT film or the like.
[0034]
The recording member 20 is conveyed by the recording member conveying rollers 7 and 9. The recording member 20 to which the image has been transferred by the transfer device 8 is permanently fixed by a fixing device (not shown) by the conveyance roller 9 and conveyed outside the image forming apparatus.
[0035]
This embodiment is characterized in that the laser lighting ratio count in the video engine 1 performed in the prior art is calculated by the laser lighting count circuit 15 in the printer engine unit.
[0036]
For this reason, in this embodiment, a specific number of video signals are sampled within a predetermined image area, the number of video signals that are on is counted, and the ratio between the count value and the total number of samples is calculated. The laser lighting ratio in a predetermined image area is calculated.
[0037]
A method of calculating the laser lighting ratio in this embodiment will be described with reference to FIG. In FIG. 2, reference numeral 112 denotes a sheet on which an image is printed. Reference numeral 113 denotes an area where an image on the sheet is printed.
[0038]
In this embodiment, the image area 113 is divided into 16 parts. Numbers 1 to 16 are assigned to the 16 divided areas. The video signal is sampled at one point in the image area from 1 to 16, and whether the video signal is on or off is determined. The on / off state of the video signal is determined at a blackened portion of each area in FIG.
[0039]
The laser lighting ratio can be calculated by counting the number of video signals turned on and dividing the number by the number of divided image areas (16 in this case). Strictly speaking, the value calculated as described above does not necessarily match the laser lighting ratio. However, if the number of samples is sufficiently large, the value calculated as described above and the actual laser lighting ratio are substantially equal.
[0040]
In the method of this embodiment, it is important to sample as many video signals as possible within an image region and to sample video signals randomly. If the above two conditions are not satisfied, the error between the calculated laser lighting ratio and the actual laser lighting ratio becomes large.
[0041]
FIG. 3 shows a typical circuit of the laser lighting count circuit of this embodiment. The operation of the laser lighting count circuit will be described with reference to FIG. These circuits are composed of synchronous digital circuits. However, the system clock is not shown.
[0042]
The video signal S1 input from the video controller 1 is received by the flip-flop 102 and converted into a synchronization signal. The sample timing generator 106 is supplied with a horizontal enable signal S3 indicating an image area in the scanning direction of the laser beam and a vertical enable signal S2 indicating an image printing area in the direction perpendicular to the scanning direction of the laser beam. The horizontal enable signal S3 can be generated by a control logic circuit (not shown) inside the printer engine based on a horizontal synchronization signal (not shown). The vertical enable signal S2 can be generated by a control logic circuit (not shown) inside the printer engine in accordance with the paper transport timing.
[0043]
The CPU 16 inputs a set value S4 corresponding to the image area to the sample timing generation unit 106. The gate 103 becomes high when the signal obtained by synchronizing the video signal S1 at the timing determined by the sample timing generation unit 106 is on.
[0044]
The counter 104 counts the number of times that the gate 103 becomes high (HIGH) within a predetermined image area, that is, the number of times that the video signal is turned on. The count value is sent to the CPU 16 when the electrostatic latent image is created in the predetermined image area (S5). The CPU 16 can calculate the laser lighting ratio in a predetermined image area from the ratio between the count value and a predetermined total number of samples (for example, the number of sections 16 in FIG. 2).
[0045]
FIG. 4 shows the configuration of the sample timing generation unit 106. The counter 110 serves as a timer for generating each of the 16 divided sections in FIG. Specifically, the CPU 16 loads a count value (S8 = S4) that counts the period during which the entire image region 113 is scanned into 16 equal parts and counts the period during which the image area 113 is scanned. A down counter is configured to decrement.
[0046]
For example, in this embodiment, when counting 10 clocks to generate one section of FIG. 2, the CPU 16 loads the count value 9 into the counter 110. The counter 110 receives a counter enable signal S7 that enables the counter 110 only during a period in which the laser scans the inside of the image area. The counter 110 performs a counting operation only in a period in which the laser scans the image area. Do.
[0047]
When the count value reaches 0, the counter 110 outputs a carry-out signal S9 and loads the value S8 from the CPU 16. Thereafter, this operation is continued. In this way, the image area 113 can be divided into 16 by the counter 110. Whether the video signal is on or off is determined only at one point in each of the 16 divided sections as described above.
[0048]
It is desirable that the timing for sampling the video signal within one section is random. The linear feedback shift register 107 is used to load a random value into the register 108. At the timing when the output S10 of the counter 110 becomes 0, the carryout signal S9 becomes high (HIGH), and the value output from the linear feedback shift register 107 is loaded into the register 108.
[0049]
Since the linear feedback shift register 107 operates during a period when the vertical enable signal S2 is high (HIGH), the period during which the linear feedback shift register 107 is operating with the counter 110 is not synchronized, so that the output can be expected to be random. The comparator 109 compares the value of the register 108 with the output S10 of the counter 110, and sets the signal S11 to high (HIGH) at the timing when both match. By adopting such a configuration, it is possible to generate the timing signal S6 for determining the on / off of the video signal once in each section and at random timing for each section.
[0050]
As described above, the CPU 16 of the printer engine can calculate the laser lighting ratio per page. Further, by storing a table (not shown) for obtaining the toner consumption amount using the laser lighting ratio and the paper size as parameters in a memory (not shown) accessed by the CPU 16, the CPU 16 refers to the table and the toner consumption amount. Can be predicted.
[0051]
(Embodiment 2)
FIG. 5 shows the configuration of another circuit of the laser lighting count circuit of this embodiment. Parts that perform the same operations as those described in the first embodiment are denoted by the same reference numerals. In this embodiment, the printer engine unit includes the circuit shown in the first embodiment except for the laser lighting count circuit shown in FIG.
[0052]
Compared with the circuit of the first embodiment, the laser lighting count circuit of the second embodiment has no signal S4 loaded from the CPU 16 to the sample timing generation unit 106, and a counter 114 is added. In the first embodiment, the count value S4 loaded by the CPU 16 is changed in accordance with the image printing area. In this embodiment, the value loaded into the sample timing generation unit is constant regardless of the image area. However, if this value is constant, the number of times the video signal S1 is sampled differs depending on the image area. Therefore, the number of denominators when calculating the laser lighting ratio varies depending on the image area.
[0053]
In the present embodiment, a counter 114 is added to count the number of times the video signal S1 is sampled. The counter 114 counts the number of times the video signal S1 in the image area is sampled.
[0054]
By sending the number S5 of video signals turned on and the total number of samples S6 counted by the counter 104 to the CPU 16, the CPU 16 can calculate the laser lighting ratio per page regardless of the image area. Further, by storing a table (not shown) for obtaining the toner consumption amount using the laser lighting ratio and the paper size as parameters in a memory (not shown) accessed by the CPU 16, the CPU 16 refers to the table and the toner consumption amount. Can be predicted.
[0055]
(Embodiment 3)
FIG. 6 shows still another circuit of the laser lighting count circuit of this embodiment. Parts that perform the same operations as those described in the first embodiment are denoted by the same reference numerals. In this embodiment, the printer engine unit includes the circuit shown in the first embodiment except for the laser lighting count circuit shown in FIG.
[0056]
The laser lighting count circuit according to the third embodiment is different from the circuit according to the first embodiment in that a counter 114 is added. In the first embodiment, the count value S4 loaded by the CPU 16 is changed in accordance with the image printing area. As a result, the number of video signals that are always sampled in the image area is always stored in the CPU as a predetermined value (for example, the number of sections 16 in FIG. 2).
[0057]
However, when the number of samples is adjusted to a predetermined number (for example, 16), the count value (S8 = S4) that the CPU 16 loads to the counter 110 in FIG. 4 can only be set to an integer, so depending on the size of the print area In some cases, the period of scanning is not divisible by the count value, and the number of samples may not be a predetermined number.
[0058]
In the present embodiment, a counter 114 that counts the number of samples in the image area is added in order to increase the accuracy of calculating the laser lighting ratio. The counter 114 counts the number of times the video signal S1 in the image area is sampled.
[0059]
By sending the number S5 of video signals turned on and the total number of samples S6 counted by the counter 104 to the CPU 16, the CPU 16 can calculate the laser lighting ratio per page with high accuracy. Further, by storing a table (not shown) for obtaining the toner consumption amount using the laser lighting ratio and the paper size as parameters in a memory (not shown) accessed by the CPU 16, the CPU 16 refers to the table and the toner consumption amount. Can be predicted.
[0060]
(Embodiment summary)
As described above, the toner consumption amount can be predicted by calculating the laser lighting ratio by the method described in the embodiment of the present invention. For this reason, the CPU 16 can accurately supply toner by the following toner replenishment sequence based on the predicted value of toner consumption, and keeps the concentration of the developer 12 in the developing device 11 constant.
[0061]
A toner replenishing method will be described with reference to FIG. With the method described in the embodiment of the present invention, the CPU 16 can calculate the laser lighting ratio per page. The actual toner replenishment amount is controlled by the CPU 16 controlling the rotation amount of the motor 18 in FIG. 1 using the paper size and the laser lighting ratio as parameters.
[0062]
For example, when the A4 size and the laser lighting ratio is 50%, it is possible to perform control such that toner is supplied by rotating the motor 18 by one rotation. As data for this control, a table (not shown) of the optimum rotation amount of the motor 18 using the paper size and the laser lighting ratio as parameters may be stored in a memory (not shown) accessed by the CPU 16. The motor rotation amount described here is an example, and the motor rotation amount is not limited to this.
[0063]
In the embodiment of the present invention, the description has been made on a single-color image forming apparatus, but the present invention can also be applied to a multicolor image forming apparatus.
[0064]
In each of the above embodiments, the toner density is adjusted based on the predicted value of toner consumption. However, the CPU 16 can use the predicted value as a parameter for temperature control of the fixing device. For example, when it can be predicted that the amount of toner consumption is large (the laser lighting ratio is high), the fixing device temperature is set high to improve the fixing performance.
[0065]
A method in which the CPU 16 performs temperature control of the fixing device based on the predicted value will be described. With the method described in the embodiment of the present invention, the CPU 16 can calculate the laser lighting ratio per page. The temperature of the fixing device corresponding to the laser lighting ratio using the laser lighting ratio as a parameter is stored in a memory (not shown) accessed by the CPU 16 as a table (not shown), so that the temperature of the fixing device is optimized. The value can be controlled. For example, by setting the temperature of the fixing device when the laser lighting ratio is less than 20% to 180 ° C., the temperature when 20% or more and less than 50% is set to 190 ° C., and the temperature when 50% or more is set to 200 ° C. , Can improve the fixability. The optimum fixing device temperature is merely an example, and is not limited to this temperature.
As described above, the number of ON of the video signal is counted, and the lighting ratio of light (laser) is calculated based on the count value. For this reason, the toner consumption can be accurately predicted from the calculated laser lighting ratio. As a result, accurate toner replenishment can be performed, and a stable image with less uneven density can be continuously output. Also, the circuit configuration can be configured only with a digital circuit, and can be configured at low cost inside the engine control logic circuit.
[0066]
【The invention's effect】
As described above, according to the present invention, it is possible to perform processing related to prediction of toner consumption with an inexpensive configuration.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a printer according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a method for calculating a laser lighting ratio according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram of a first embodiment of the present invention.
FIG. 4 is a configuration diagram of a sample timing generation unit according to the embodiment of the present invention.
FIG. 5 is an explanatory diagram of a second embodiment of the present invention.
FIG. 6 is an explanatory diagram of a third embodiment of the present invention.
FIG. 7 is an overall configuration diagram of a conventional printer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Video controller 2 Laser driver 3 Polygon mirror 4 Reflecting mirror 5 Charger 6 Photosensitive drum 7 Recording member conveyance roller 7
8 Transfer device 9 Recording member conveying roller 10 Developing roller 11 Developing device 12 Developer 13 Screw 14 Toner replenishing container 15 Laser lighting count circuit 16 CPU
17 Motor driver board 18 Motor 19 Gear 20 Recording member 102 Flip-flop 103 Gate 104 Counter 106 Sample timing generation unit 107 Linear feedback shift register 108 Register 109 Comparator 110 Counter 112 Paper 113 Image area 114 Counter S1 Video signal S2 Vertical enable signal S3 Horizontal Enable signal S4 Count value S5 for scanning one section Count value S6 when video signal was on S6 Total number of samples S7 Count enable signal S8 Count value for scanning one section S9 Carryout signal S10 Counter output S11 Timing signal

Claims (8)

A laser beam light emitting element; laser control means for controlling light emission of the laser beam light emitting element based on an input signal; an image carrier for forming an electrostatic latent image based on light emission by the laser beam light emitting element; An image forming apparatus comprising: a developing unit that attaches toner to an electrostatic latent image on an image carrier and visualizes the toner image;
A signal input to the laser control means , comprising a video signal for controlling light emission of the laser beam light emitting element, and a counting means for counting the input video signal,
Said counting means, for the input video signal, without counting the image region all of the video signal for one page, and counting the video signal at random a plurality of locations in the entire image region for one page,
Predicting toner consumption according to the ratio of the number of video signals that cause the laser beam emitting element to emit light at the count with respect to the number of samples of the video signal at the plurality of locations, or at the plurality of locations An image forming apparatus that performs processing corresponding to a toner consumption amount according to a ratio of a number of video signals that cause the laser beam light emitting element to emit light at the count with respect to the number of samples of video signals . 2. The image according to claim 1, wherein the counting means counts the input video signal at random locations corresponding to each of the sample sections into which the entire image area of one page is divided. Forming equipment. Wherein in response to each of the sampling interval, further comprising a random signal generating means for generating a video signal indicating a random position to count the video signal,
The counting means, the image forming apparatus according to claim 2, characterized in that counting the video signal the input in accordance with a video signal indicating a random location that is generated.   The image forming apparatus according to claim 2, further comprising a unit that divides the image area of the one page based on a count of a counter value indicating the image area. A laser beam light emitting element; laser control means for controlling light emission of the laser beam light emitting element based on an input signal; an image carrier for forming an electrostatic latent image based on light emission by the laser beam light emitting element; An image forming method in an image forming apparatus comprising: a developing device that attaches toner to an electrostatic latent image on an image carrier and visualizes the toner image;
A signal input to the laser control means, the video signal for controlling the light emission of the laser beam light emitting element is input, and a counting step of counting the input video signal is provided.
The counting step, for the input video signal, without counting the image region all of the video signal for one page, and counting the video signal at random a plurality of locations in the entire image region for one page,
Predicting toner consumption according to the ratio of the number of video signals that cause the laser beam emitting element to emit light at the count with respect to the number of samples of the video signal at the plurality of locations, or at the plurality of locations An image forming method comprising: performing a process corresponding to a toner consumption amount according to a ratio of a number of video signals for causing the laser beam emitting element to emit light at the count with respect to a number of samples of a video signal . 6. The image according to claim 5, wherein the counting step counts the input video signal at a random location corresponding to each of the sample sections into which the entire image area of one page is divided. Forming method. A random signal generating step of generating a video signal indicating a random location for counting the video signal corresponding to each of the sample sections;
The counting process, the image forming method according to claim 6, characterized in that counting the input video signal in accordance with a video signal representing a random location that is generated.   The image forming method according to claim 6, further comprising a step of dividing the image area of the one page based on a count of a counter value indicating the image area.

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