JP2005106525A - Method for controlling optical sensor, program and storage medium, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a decrease in throughput of an image forming apparatus, while maintaining the lifetime of a light emission element such as an LED to the same extent as the lifetime of the image forming apparatus itself. <P>SOLUTION: In a method for controlling an optical sensor including at least one light source and at least one light receiving element, the method includes: a step, when the light receiving element does not detect the amount of the light from the light source, for intermittently turning on the light source at the amount of the light not less than that when the light receiving element performs the detection; a step, when the light receiving element detects the amount of the light from the light source, for fully turning of the light source; and a step, after the full turning on, for detecting the amount of the light from the light source by the light receiving element after the lapse of a prescribed time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for controlling a light source used in an optical sensor unit, and an image forming apparatus such as an electrophotographic system, electrostatic recording system, or other copying machine or printer equipped with a sensor using the control method. .

  FIG. 10 shows an example of a sensor that detects reflected light from toner using a photodiode as a light receiving element. FIG. 10B is a circuit that converts the photocurrent generated in the photodiode 301 into a voltage V303 by the resistor 300. FIG. Reference numeral 301 in FIG. 10A denotes light detection means using the photodiode shown in FIG. 10B, 302 denotes an LED serving as a light source, and 310 denotes a detection target toner patch formed on the transfer material 1. It is. The reflected light from the toner patch enters the sensor 301.

  On the other hand, when an electrophotographic image forming apparatus using an intermediate transfer member is taken as an example, the density and chromaticity of the obtained image will fluctuate if fluctuations occur in various parts of the apparatus due to environmental changes or long-term use. . In particular, in the case of a color image forming apparatus, there is a risk that the color balance may be lost even with a slight change in toner density. Therefore, it is necessary to always maintain a constant density and gradation.

  Therefore, the absolute humidity measured by the temperature / humidity sensor for each color toner has gradation correction means such as several kinds of exposure amount corresponding to absolute humidity, process conditions such as development bias, and look-up table (LUT). Based on the above, the process conditions and gradation correction values at that time are selected. In addition, a toner image (hereinafter referred to as a patch or a toner patch) for detecting the density with each color toner is obtained so that a constant density, gradation, and color can be obtained even if fluctuations occur in each part of the apparatus during use. Create a patch on an intermediate transfer member or transfer material, detect this patch with an optical sensor, and use the results to feed back process conditions such as exposure amount and development bias, and control the density to obtain a stable image. (For example, refer to Patent Document 1).

  However, a sensor that detects the density of the toner formed on the intermediate transfer member and the color of the toner fixed on the transfer material has the following problems. For example, when a light emitting element such as an LED is fully lit, its lifetime is shorter than the lifetime of the image forming apparatus, and deteriorates with the lighting time and the amount of light decreases. Therefore, it is usually necessary to turn off the light and turn it on each time detection is performed to keep the total lighting time short.

  It also measures the reflectivity from several toners with different densities and colors and controls the toner density sensor used for toner density control, a sensor that detects the color of the toner by spectrally reflecting the reflected light with a color filter, and the transfer material. Sensors that detect the surface condition and judge the paper quality are different from photointerrupters that do not suffer from slight fluctuations in the amount of light in order to determine whether the sensor is shielded from light or not. The image forming conditions of the image forming apparatus are adjusted by determining the toner density, color, and surface properties by slight differences.

If detection is performed in a state in which the light amount of the light emitting element is not stable, the image forming conditions that should be corrected using the sensor are deviated from the appropriate conditions, and the image quality is adversely affected. Therefore, it is essential to maintain a stable light quantity during the measurement period. However, in this case, it is necessary to wait for the amount of light after lighting to stabilize, and the throughput of the image forming apparatus decreases.
JP 2003-076077 A

  As described above, conventionally, it has been impossible to prevent the throughput of the image forming apparatus from being lowered while maintaining the life of a light emitting element such as an LED as long as the life of the image forming apparatus itself.

  The present invention has been made in view of the above prior art, and provides an image forming apparatus capable of detecting an accurate signal without reducing the throughput of the image forming apparatus, and improving usability, image quality, and image quality. The purpose is to do.

  The present invention for solving the above-described problem is an optical sensor control method for controlling an optical sensor including at least one light source and one light receiving element, and the light receiving element does not detect the amount of light from the light source. The step of intermittently lighting the light source at a light amount equal to or greater than the amount of light detected by the light receiving element, and the step of fully lighting the light source when the light receiving element detects the light amount from the light source, and And a step of detecting the amount of light from the light source by the light receiving element after a predetermined time has elapsed after all the lights are turned on.

  The present invention further relates to an optical sensor control method for controlling an optical sensor including at least one light source and one light receiving element, wherein the light source is intermittently turned on, and the light receiving element detects the amount of light from the light source. A step of controlling the accumulation operation of the light receiving element so that the accumulation timing of the light receiving element is synchronized with the light emission timing of the light source.

  The present invention also provides a photosensitive member, a latent image forming unit that forms an electrostatic latent image on the photosensitive member, a plurality of developing units that develop the electrostatic latent image into a toner image, and a toner image transfer unit. An image that includes a transfer unit that transfers to a material, a fixing unit that fixes the transferred image, a conveyance unit that conveys the transfer material, and one or more optical sensors, and performs calibration based on the detection results of the optical sensors. A forming apparatus, wherein the optical sensor is controlled by the above-described optical sensor control method.

  As described above, according to the present invention, it is possible to maintain the life of the light emitting element at the same level as the life of the image forming apparatus itself and not to reduce the throughput of the image forming apparatus.

[First Embodiment]
Detailed embodiments of an image forming apparatus and a light source control method to which the present invention is applied will be described below with reference to the drawings.

  First, a sensor for detecting the color of toner transferred onto a transfer material of an image forming apparatus will be described with reference to FIG. 2 as a sensor to which the present invention is applied. FIG. 2 is a diagram illustrating the relationship between the light receiving unit and the light source unit in the optical sensor to which the present invention is applied.

  In FIG. 2, reference numeral 101 denotes a light receiving portion of the sensor (hereinafter also simply referred to as sensor 101), and a specific configuration example is shown in FIG. Reference numeral 100 denotes a sensor light source unit (hereinafter also simply referred to as a light source 100), and a specific configuration example is shown in FIG.

  First, light emitted from the light source 100 is incident on the toner patch 102 formed on the transfer material 1 at about 45 °, diffusely reflected on the toner surface, and spreads to the upper surface. The sensor 101 separates the reflected light by RGB color filters (not shown) formed on the chip surface, and detects the magnitude of the output of the sensor corresponding to each color filter.

  The toner patch 102 for detecting the color tone is formed on the transfer material by a single color or mixed color patch 102 of CMYK toners. Based on the RGB output of each patch 102 obtained by the sensor 101, a control unit (not shown) of the image forming apparatus feeds back image forming conditions so that the color of the image on the transfer material becomes a desired value. .

  Next, the light source 100 will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of a specific configuration of the light source 100. The light source is composed of a light source (in this case, a white LED) 103 having an emission spectrum over the entire visible light, an LED driving current control circuit including an operational amplifier 105, a resistor 104, and an NPN transistor 110. A voltage 109 for controlling the current flowing through the LED is supplied from a DA converter (not shown).

  Feedback is applied by the operational amplifier 105 so that the same voltage as the voltage 109 input to the non-inverting input terminal of the op amp is generated on the anode side of the resistor 104. Therefore, a current determined by the resistance values of the voltages 109 and 104 flows to the emitter of the NPN transistor, and almost the same collector current becomes the drive current of the LED 103. Therefore, the LED drive current can be adjusted by the voltage 109.

  Next, a specific configuration example of the light receiving unit will be described with reference to FIG. In FIG. 4, 121, 122, and 123 surrounded by a dotted line indicate a circuit configuration of one pixel of a CMOS sensor that is a kind of storage type sensor. In the following, a description will be given in particular of 121 in this one-pixel circuit. However, the description of 121 can be similarly applied to the one-pixel circuits 122 and 123.

  In the one-pixel circuit 121, reference numeral 124 denotes a photodiode that detects light. An NMOS transistor 125 resets the photodiode to the reset potential Vr based on the sensor reset signal φr. A PMOS transistor 126 outputs the anode potential Vpd1 of the photodiode 124 by a source follower. Reference numeral 127 denotes a PMOS transistor that applies a constant voltage Vb to the gate and supplies a constant current to the force follower.

  128 is an NMOS transistor for collectively transferring the output of each sensor to the capacitor 129 based on the transfer signal φt, and 130 outputs the charge transferred to the capacitor 129 to the output line Vout according to the output φsr1 of the shift register 132. An NMOS transistor 131 is an NMOS transistor for resetting the output line Vout to the voltage Vhr based on the output line reset signal φhr.

  In FIG. 4, this sensor is provided for three pixels (121, 122, 123) corresponding to each color of RGB, and by providing an RGB on-chip color filter (not shown) on the surface of each pixel, Of these, signals of three colors of R, G, and B can be detected. The signal output to the output line Vout is buffered by an operational amplifier (not shown) and then AD converted, and the signal corresponding to the R, G, and B wavelengths of the reflected light reflected on the toner surface is accumulated for a predetermined time. Can be obtained.

  Each drive signal is supplied from a CPU or the like (not shown) that controls the operation of the image forming apparatus.

  The operation when the CMOS sensor of this embodiment acquires data from one patch 102 will be described using the one-pixel circuit 121 as an example with reference to the timing chart of FIG.

  In FIG. 5, first, φr becomes high at time t1, the NMOS transistor 125 is turned on, and the anode of the photodiode 124 is reset to the voltage Vr. Next, when φr becomes low at time t2 and the reset of the photodiode is released, the accumulation operation of the sensor is started.

  Note that the timing of t2 is set so that the toner patch 102 on the transfer material is within the detection range of the sensor in order to avoid color mixing at the time of color measurement with the adjacent toner patch 102. During the accumulation, the anode potential Vpd1 of the photodiode 125 rises due to the photocurrent due to the R component of the incident light. Similarly, the anode potentials Vpd2 and Vpd3 of the photodiodes of the pixels 122 and 123 also rise according to the intensity of the incident light G component and B component.

  After the predetermined accumulation time has elapsed, when φt is raised at time t3, the NMOS transistor 128 is turned on, and the voltage obtained by buffering Vpd1 with the source follower circuit is transferred to the capacitor 129. At time t4, φt is set low and the transfer to the capacitor 129 is terminated. During this time, ts1 = t4-t2 is the accumulation time. The pixels 122 and 123 operate similarly.

  Thereafter, the shift register 132 is operated, φsr1 is set to high, the NMOS transistor 130 is turned on, and the output of the sensor is read to Vout. The read signal is AD converted by an AD converter (not shown) and stored in a memory of a CPU (not shown) that controls the operation of the image forming apparatus. After reading the output of one sensor, the output line is reset to Vhr by the NMOS transistor 131 by making φhr high. The shift register turns on φsr2 and φsr3 one after another and reads the sensor output corresponding to the subsequent G and B filters.

  Next, an image forming apparatus configuration for realizing the present invention will be described with reference to FIG. Assuming that the image forming apparatus corresponding to the present invention is 401, a print command and data from an external personal computer or the like are input via the interface unit 402. First, a print command is input to an engine control unit 404 including a CPU, a memory, a motor drive circuit, a sensor control circuit, a laser control circuit, a high voltage control circuit, and the like through an image processing unit 403, and image data is input to each image processing unit 403. The exposure time corresponding to the toner is converted and input to the engine control unit. The engine control unit 404 drives the charging / exposure unit 405 based on the image data to form an electrostatic latent image on the photoreceptor. Further, the engine control unit controls the developing unit 406 to form a toner image, and the transfer unit 407 transfers the toner onto the transfer material. In the case of an image forming apparatus using an intermediate transfer member, the transfer is performed twice from the developing device to the intermediate transfer member and further to the transfer material. Next, the engine control unit 404 drives the fixing unit 408 to fix the toner on the transfer material. These series of movements of the transfer material are executed by the engine control unit 404 controlling the conveying unit 409. When performing calibration, the engine control unit 404 drives a sensor 410 including a light emitting unit and a light receiving unit to detect the toner amount on the developing drum and the toner amount on the intermediate transfer member. At this time, the engine control unit 404 controls blinking of the light emitting unit, driving of the light receiving unit, and signal reading.

  Next, control of the state of the image forming apparatus and the light source 100 in the present embodiment will be described with reference to FIGS. FIG. 1 is a timing chart for explaining the relationship between the operation of the image forming apparatus and the operation of the light source 100. FIG. 11 is a flowchart of the control processing of the image forming apparatus and the optical sensor in the present embodiment.

  First, FIG. 1A shows an example of an operation state of the image forming apparatus. When the power is turned on, (1) warm-up starts, (2) engine calibration is executed, and (3) printing is possible (ready state). (4) When the user sends data to be printed from a personal computer or the like, the print state is entered. (5) When printing is completed, the printer returns to the ready state.

  In (6) and (7), printing and the ready state are repeated again. In the ready state of (7), when printing is not performed for a predetermined time or more, the mode is shifted to the low power mode of (8), and the power supply of most circuits of the image forming apparatus is cut to suppress power consumption.

  After that, when a print request comes, the weight is first adjusted in (9) and the fixing temperature is adjusted to prepare for printing (in this case, the power is kept on, but the environment changes or the cartridge changes, and then calibration is performed again. The calibration is performed again in (10), and (12) printing is started as soon as it becomes ready (11).

  With respect to the operation of the image forming apparatus, the sensor 101 for detecting the color of the toner after fixing shown in FIG. 2 is a test patch on the transfer material in the calibration steps (2) and (10). 102 is detected and the result is fed back to the control of the image forming apparatus in order to correct the color shift. In this embodiment, as shown in FIG. 1 (b), the light source state of this sensor is normally controlled to be intermittently lit and fully lit when calibration is performed.

  The operation of the image forming apparatus and the control of the optical sensor will be described with reference to FIG. 11. When the power of the image forming apparatus is turned on in step S1101 ((1) in FIG. 1A), calibration in step S1102 is performed. In step S1103, the light source 100 is completely turned on. In step S1104, it is determined whether a predetermined time Tp has elapsed after the light source is turned on. If it is determined that Tp has elapsed, the accumulation operation of the sensor 101 is started in step S1105. The predetermined time Tp will be described later in connection with FIG.

  FIG. 12 is a timing chart illustrating the relationship between the light source lighting timing and the accumulation operation start timing. Here, after the light source 100 is completely turned on, after a predetermined time Tp has elapsed, the reset signal φr of the sensor 101 becomes high, and the accumulation operation is started.

  Subsequently, in step S1106, a predetermined calibration is executed. If it is determined in step S1107 that the calibration is completed, the light source 100 is intermittently turned on in step S1108. Thereafter, intermittent lighting is maintained until a calibration execution request is received again (YES in step S1109).

  In the intermittent lighting described above, for example, by intermittently lighting with a duty of 1/10 in a normal state, the light emission time can be reduced to about 1/10 compared to the case of always lighting, and a decrease in light emission amount and failure due to element deterioration can be suppressed. . In this case, the lighting time is, for example, 10 msec, and the extinguishing time is, for example, 90 msec. Note that the present invention is not limited to these numerical values, and for example, the lighting time may be 1 msec and the extinguishing time may be 9 msec. However, if these times are set long, the temperature change of the LED becomes large, which is not preferable.

  As described above, by intermittently lighting the light emitting element, it is possible to control the light amount (temperature) of the light emitting element so as not to fall below a predetermined light amount. Therefore, as shown in FIG. 6, a certain amount of light can be obtained immediately after lighting.

  FIG. 6 is a graph showing the light amount (temperature) of the light emitting element and the lighting time characteristics. Curve 1 shows the relationship between the amount of light and the lighting time when the light is turned on again from a state where the light is completely turned off without intermittent lighting. Curve 2 shows the amount of light when the light is turned on again during intermittent lighting. The relationship with lighting time is shown.

  In FIG. 6, the allowable range of the light amount is that the influence of the change in the light amount from the light source on the determination of the toner density, the color, and the surface property by the sensor 101 can be ignored. It means the fluctuation range of the amount of light that becomes smaller than the accuracy. Therefore, if the light level does not reach the light amount tolerance range, the light amount fluctuation will affect the determination as a density fluctuation. Since fluctuations within the range cannot be detected by the sensor 101, the influence on the determination result can be ignored.

  As can be understood with reference to curve 2, by intermittently turning on the light, the temperature of the light emitting element can be raised halfway between the light-off state and the light-on state. After that, the time for the light amount to stabilize to the allowable range of detection error can be greatly shortened (T1 → T2), and quick calibration can be performed, improving usability. Further, in the present embodiment, the predetermined time Tp until the accumulation operation of the sensor 101 is started after full lighting is set to a value equal to or greater than T2, and the influence of the variation in the light amount on the calibration result is eliminated.

  Thus, by setting the light source to intermittent lighting except when the sensor is detected, the detection time can be shortened even if there is a sudden calibration request from the user. In the state where most of the power of the image forming apparatus is turned off as in the power save state and the state cannot be shifted to the detection state (the patch 102 cannot be formed immediately), the light source can be turned off as shown in FIG. It goes without saying that it is good.

  Furthermore, if the light quantity of the light source for intermittent lighting (variable by the drive current in the case of LED) is made larger than the light quantity for full lighting at the time of detection, the difference in the light quantity (temperature) of the light source before detection and at the time of detection can be reduced. The time during which the light amount is stabilized to the allowable range can be further shortened, and usability can be improved.

  In the present embodiment, an example of a CMOS sensor is shown as the light receiving element, but it is needless to say that the light receiving element is not limited to a CMOS sensor and is not limited to a storage type sensor.

  In this way, intermittently turning on the light source before the start of detection suppresses the light emission time of the light source so as not to deteriorate the characteristics, and also increases the temperature of the light source to some extent before starting the detection to allow the amount of light to be constant. This shortens and acts to suppress a decrease in throughput of the image forming apparatus. Keeping the light intensity during intermittent lighting larger than the light intensity during full lighting reduces the temperature difference between the light source before detection and the temperature of the light source during detection, further increasing the time during which the light intensity during all lighting is constant. This shortens and acts to suppress a decrease in throughput of the image forming apparatus.

  As described above, according to the present invention corresponding to the present embodiment, it is possible to shorten the time from when all the lights are turned on at the start of detection to when the light quantity is stabilized, to improve usability and to prevent a decrease in detection accuracy. Further, by performing intermittent lighting while not detecting, it is possible to suppress the lighting time with respect to the lifetime of the light source, and it is possible to avoid a light amount reduction or failure of the light source.

[Second Embodiment]
In the first embodiment, the light source of the optical sensor is normally turned on (except in the power saving state) and turned on at the time of detection. In this case, although it is shortened, a wait time (T2) is required until the light amount can be stably detected as indicated by the curve (2) in FIG. In the present embodiment, a light source control method is provided in which the wait time is further shortened to be substantially zero.

  An example of a sensor that detects the color of the toner will be described with reference to FIG. In this figure, the light emission timing of the light source, a part of driving pulses φr and φt of the storage type sensor shown in FIG. 4 and the sensor output Vout are overlapped. The light source is always turned on intermittently including the detection timing. Therefore, the light quantity at the time of light emission is constant. Here, the constant light amount means that the integrated value of the light amount during the lighting time is constant, not the instantaneous light amount of the element.

  When executing calibration (including measurement items such as normal color misregistration detection, density detection, and tint detection), the corresponding sensor becomes the timing for detecting the patch 102, and the transfer material on which the patch 102 is mounted is the detection position of the sensor. The sensor accumulates in synchronization with the light emission timing of the light source.

  As described in the first embodiment, the accumulation time of the sensor is from when φr falls to when φt falls. The first accumulation in FIG. 7 shows accumulation / reading with the light source turned off in order to obtain data for correcting the dark output of the sensor.

  In this case, accumulation is performed substantially in synchronization with the timing of driving (turning off) the light source so that the light source emits light during accumulation and no error occurs in the detection of the dark output of the sensor. The second and subsequent accumulations are for detecting the reflected light of the patch 102. In this example, the accumulation is controlled in synchronization with the light emission timing of the light source, and the accumulation is controlled to be terminated before the light is turned off.

  In this embodiment, since the light source continues to be intermittently lit under the same conditions, the temperature of the light emitting element is constant, and the amount of light emitted during the lighting time of the light emitting element is also constant. Therefore, the patch 102 can be detected under the same light amount condition from the time when the first patch 102 is detected to the time when the last patch 102 is detected, and the waiting time is eliminated and accurate detection can be performed under a stable light amount. . Of course, since the light source is intermittently lit, it is possible to avoid the influence of deterioration of the light source (decrease in the amount of light) due to changes over time.

  In the present embodiment, an example is shown in which the accumulation time of the accumulation type sensor is included in the timing at which the light source emits light. However, the state in which the light source is not emitting light during accumulation is a state in which no photocurrent is generated in the light receiving portion of the sensor, and therefore the light emission timing may be controlled to be within the accumulation period.

  As described above, according to the present invention corresponding to the present embodiment, the light source of the optical sensor is always intermittently turned on to be in a steady state, and the optical sensor is detected in accordance with the intermittent operation of the light source at the time of detection. Thus, the wait time at the start of detection can be further reduced, and further usability can be improved while avoiding a decrease in light quantity and failure of the light source.

  Moreover, since it is sufficient that the accumulation time is completely included in the light emission of the light emitting element or the light emission is performed at some timing within the accumulation time, the intermittent lighting control of the light emitting element and the accumulation operation control of the sensor are strictly performed. Since it is not necessary to synchronize, the burden on the control system is reduced.

[Third Embodiment]
In the present embodiment, the optical sensor control method shown in the first and second embodiments is applied to improve the printing performance and usability of the image forming apparatus.

  With reference to FIG. 8, an outline of the overall configuration of a laser printer as a multicolor image forming apparatus equipped with the sensor of the present invention will be described. The image forming apparatus in the present invention includes image forming apparatuses such as electrophotographic and electrostatic recording type copying machines, and ink jet type printers.

  The color laser printer forms an electrostatic latent image with image light formed based on an image signal in an image forming unit, develops the electrostatic latent image to form a visible image, and further converts the color visible image into an image. It is transferred to a transfer material that is a recording medium, and then a color visible image is fixed.

  The image forming unit includes photosensitive drums 5Y, 5M, 5C, and 5K arranged in parallel for the number of development colors, injection charging units 7Y, 7M, 7C, and 7K as primary charging units, and developing units 8Y, 8M, 8C, and 8K. The toner cartridges 11Y, 11M, 11C, and 11K, the intermediate transfer body 12, the paper feeding unit, the transfer unit, and the fixing unit 13 are configured.

  The photosensitive drums 5Y, 5M, 5C, and 5K are configured by applying an organic optical transmission layer on the outer periphery of an aluminum cylinder, and are rotated by transmission of a driving force of a driving motor (not shown). 5M, 5C, and 5K are rotated counterclockwise according to the image forming operation.

  Exposure light to the photosensitive drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and is electrostatically sequentially exposed by selectively exposing the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. A latent image is formed.

  As primary charging means, four injection chargers 7Y, 7M, 7C, and 7K for charging yellow (Y), magenta (M), cyan (C), and black (K) photosensitive drums are provided for each station. Each injection charger is provided with sleeves 7YS, 7MS, 7CS, and 7KS.

  As developing means, in order to visualize the electrostatic latent image, four developing devices 8Y, 8M for developing yellow (Y), magenta (M), cyan (C), and black (K) for each station, 8C and 8K, and each developing device is provided with sleeves 8YS, 8MS, 8CS, and 8CK. Each developing device is detachably attached to the apparatus main body.

  The intermediate transfer body 12 is an endless belt that is stretched around the driving roller 18a and the driven rollers 18b and 18c, and is in contact with the photosensitive drums 5Y, 5M, 5C, and 5K, and rotates in the clockwise direction when forming a color image. And is sequentially transferred by the action of the primary transfer rollers 6Y, 6M, 6C, and 6K for the respective colors.

  A transfer material 1 is accommodated in a paper feed cassette 2 or a paper feed tray 3 as a paper feed means (paper feed port), and the transfer material 1 is a transport path 25 constituted by a paper feed roller 4 and a transport roller 24. , And reaches the registration roller 23. This is detected by the pre-registration sensor 19.

  At the time of image formation, the pre-registration sensor 19 matches the timing at which the color visible image on the intermediate transfer body 12 reaches the transfer region, and stops the transfer material transfer for a predetermined time. The transfer material 1 is fed from the registration roller 23 to the transfer region, and the secondary transfer roller 9 comes into contact with the intermediate transfer body 12 to carry the transfer material 1 by nipping and transferring the color on the intermediate transfer body 12 to the transfer material 1. Visible images are simultaneously superimposed and transferred.

  The secondary transfer roller 9 is brought into contact with the intermediate transfer body 12 as indicated by a solid line while a color visible image is superimposed and transferred onto the intermediate transfer body 12, but is indicated by a dotted line at the end of the printing process. Separated into position.

  The fixing unit 13 fixes the transferred color visible image while transporting the transfer material 1. The fixing roller 14 heats the transfer material 1 and the transfer material 1 to the fixing roller 14 as shown in FIG. And a pressure roller 15 for pressure contact.

  The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and heaters 16 and 17 are incorporated therein, respectively. That is, the transfer material 1 holding the color visible image is conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.

  The transfer material 1 after fixing the visible image is then discharged to a paper discharge section (not shown) by a discharge roller (not shown), and the image forming operation is completed. The discharge of the transfer material 1 from the fixing unit 13 is detected by a fixing discharge sensor 20.

  The cleaning unit 21 stores waste toner after the four color visible images formed on the intermediate transfer body 12 are transferred to the transfer material 1. The color misregistration detection means 22 forms a color misregistration detection pattern on the intermediate transfer body 12, detects the amount of misregistration between the colors in the main scanning and sub scanning directions, and finely adjusts the image data to reduce the color misregistration. Give feedback.

  A sensor 151 for detecting the color of the toner is arranged on the paper discharge side from the fixing device, and detects the color of the toner fixed on the transfer material 1. Further, the toner density detection unit 152 is disposed in the vicinity of the color misregistration detection unit 22 and detects the toner density (mounting amount) on the intermediate transfer body 12 before fixing.

  When the image forming apparatus is used, if a change occurs in each part of the apparatus due to a change in environment or use for a long time, the density or chromaticity of the obtained image changes. In particular, in the case of an electrophotographic color image forming apparatus, there is a risk that the color balance may be lost even with a slight change in density. These sensors are provided because it is necessary to avoid this and always maintain a constant density and gradation.

  These sensors detect variations in the color of the toner being used and variations in the amount of toner applied to the intermediate transfer member, and feedback the process conditions such as exposure amount and development bias based on the results, thereby adjusting the color and density. By performing the control, a stable image is obtained.

  A paper quality sensor 153 disposed in the vicinity of the registration roller 23 detects the quality of the transfer material, such as whether the transfer material is plain paper, glossy paper, or an OHP sheet, and feeds back to the development bias and fixing conditions to obtain an optimum image. As an example, there is a configuration as shown in FIG.

  The photodiode 155 includes a light source 154 and two photodiodes 155 and 156, and one photodiode 155 detects irregularly reflected light components from the transfer material 1, and the other photodiode 156 detects regular reflection light from the transfer material 1.

  Since the specular reflection component increases as the gloss of the transfer material increases, the output of the two photodiodes is converted to IV by resistance, converted to a digital signal by an AD converter, and then compared with a CPU to compare the ratio of both. Can be detected.

  By using the control method described in the first and second embodiments for the control of the optical sensor that detects the analog magnitude of the incident light quantity like these sensors, the usage period of the image forming apparatus However, even if the life of the light source is longer than that of the light source, the light source is intermittently turned on at a timing other than the detection timing, so that it is possible to suppress a decrease in the light amount or failure of the light source.

  Furthermore, since the time until the light intensity becomes constant after the light source is turned on can be shortened or eliminated, the wait time during detection can be shortened without the failure of the light source and the decrease in detection accuracy, and the usability of the image forming apparatus Can be improved.

  As described above, according to the present embodiment, it is possible to improve the usability by reducing the toner color, the toner density, and the wait time for detecting the paper quality, and the toner color and density can be improved regardless of the type of the transfer material. An image forming apparatus that suppresses fluctuations and improves image quality can be obtained.

  Although an example of a color image forming apparatus has been described here, the paper quality sensor is also effective in a monochrome color image forming apparatus, and the present invention is not limited to a color image forming apparatus.

[Other Embodiments]
Note that the present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, and a printer), and a device (for example, a copying machine and a facsimile device) including a single device. You may apply to.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

It is a timing chart which shows an example of the control corresponding to the 1st Embodiment of this invention. It is a figure explaining an example of the relationship between the sensor and light source corresponding to embodiment of this invention. It is a figure which shows the structural example of the light source corresponding to embodiment of this invention. It is a figure which shows the specific structural example of the accumulation | storage type sensor corresponding to embodiment of this invention. It is a timing chart which shows operation of a storage type sensor corresponding to an embodiment of the present invention. It is a figure which shows the relationship between the lighting time of the light source corresponding to the 1st Embodiment of this invention, and light quantity. It is a timing chart which shows an example of control corresponding to a 2nd embodiment of the present invention. It is a block diagram which shows the structural example of the image forming apparatus corresponding to the 3rd Embodiment of this invention. It is a figure which shows the specific structural example of a paper quality sensor. It is a figure which shows the structure of the sensor which detects the reflectance light from the conventional toner. It is a flowchart of the process corresponding to the 1st Embodiment of this invention. 3 is a timing chart showing the relationship between the lighting timing of the light source 100 and the accumulation timing of the sensor 101 corresponding to the first embodiment of the present invention. 1 is a diagram illustrating a configuration of an image forming apparatus corresponding to an embodiment of the present invention.

Explanation of symbols

151 Sensor for detecting the color of toner 152 Sensor for detecting the density of toner 153 Sensor 121 to 123 for detecting paper quality One pixel circuit 124 of the accumulation type sensor Photo diode 129 Capacitance 126, 127 PMOS transistors 125, 128, 130, 131 NMOS transistor 132 shift register 103, 302 LED
104, 300 Resistor 105 Operational amplifier 5Y, 5M, 5C, 5K Photosensitive drum 6Y, 6M, 6C, 6K Primary transfer roller 7Y, 7M, 7C, 7K Injection charging means 8Y, 8M, 8C, 8K Developing means 11Y, 11M, 11C, 11K toner cartridge 12 intermediate transfer member 13 fixing unit 10Y, 10M, 10C, 10K scanner 7YS, 7MS, 7CS, 7KS sleeve 8YS, 8MS, 8CS, 8CK sleeve 12 intermediate transfer member 18a driving roller 18b, 18c driven roller 2 paper feeding cassette 3 Feed tray 4 Feed roller 24 Transport roller 25 Transport path 23 Registration roller 19 Pre-registration sensor
9 Secondary transfer roller 9
14 Fixing roller 15 Pressure roller 16, 17 Heater
20 Fixing paper discharge sensor 21 Cleaning means

Claims (11)

An optical sensor control method for controlling an optical sensor including at least one light source and one light receiving element,
When the light receiving element has not detected the light amount from the light source, intermittently lighting the light source at a light amount equal to or greater than the light amount at the time of detection by the light receiving element;
When the light receiving element detects the amount of light from the light source, turning on the light source, and
And a step of detecting the amount of light from the light source by the light receiving element after a predetermined time has elapsed after the light is all turned on. The optical sensor is mounted on an image forming apparatus,
The method of controlling an optical sensor according to claim 1, further comprising a step of turning off the light source when the image forming apparatus is in a standby state.   3. The method of controlling an optical sensor according to claim 1, wherein the predetermined time is equal to or longer than a time during which a change in light amount of the light source that is fully lit is equal to or less than a detection accuracy of the light receiving element. An optical sensor control method for controlling an optical sensor including at least one light source and one light receiving element,
Intermittently lighting the light source;
And a step of controlling the accumulation operation of the light receiving element so that the accumulation timing of the light receiving element is synchronized with the light emission timing of the light source when the light receiving element detects the amount of light from the light source. And a method for controlling the optical sensor. In the control step of the accumulation operation,
5. The optical system according to claim 4, wherein the storage operation of the light receiving element is started after the light source is turned on, and the storage operation is controlled so that the storage operation is ended before the light source is turned off. Sensor control method. In the control step of the accumulation operation,
The optical operation according to claim 4, wherein the accumulation operation of the light receiving element is started before the light source is turned on, and the accumulation operation is controlled so that the accumulation operation is ended after the light source is turned off. Sensor control method.   The method of controlling an optical sensor according to claim 1, wherein the light source is an LED, and the light receiving element is a storage type sensor.   An optical sensor control program for causing a computer to execute the optical sensor control method according to claim 1.   A computer-readable storage medium storing the optical sensor control program according to claim 8.   A photosensitive member, a latent image forming unit that forms an electrostatic latent image on the photosensitive member, a plurality of developing units that develop the electrostatic latent image into a toner image, and a transfer unit that transfers the toner image to a transfer material An image forming apparatus comprising: a fixing unit that fixes a transferred image; a conveying unit that conveys a transfer material; and one or more optical sensors, wherein calibration is performed based on a detection result of the optical sensor. An image forming apparatus, wherein the optical sensor is controlled by the method for controlling an optical sensor according to any one of 1 to 7.   9. The image forming apparatus according to claim 8, wherein the optical sensor detects at least one of a density of toner before fixing, a color of toner after fixing, or a material of a transfer material.

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