JP4061868B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus used for a copying machine, a printer, or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus used in a copying machine, a printer, or the like uses exposure light modulated based on an image signal obtained by scanning light along an original surface or an externally input image signal. A latent image is formed by irradiating a photosensitive drum charged in this manner, and the latent image is developed with toner by a developing device to form a toner image on the photosensitive drum, and the toner image is transferred and fixed on a sheet. In order to make the density of the image formed on this paper appropriate, a toner patch is formed in a non-image area, the density is measured, and the measured toner patch In general, an ADC (Auto Density Control) method that compares image density with target density, adjusts image forming parameters that affect image density, and supplies toner is generally used. To have.
[0003]
However, the ADC sensor used to measure the density of the toner patch in the ADC system often varies in output due to toner adhesion or environmental temperature change over time, so it is necessary to periodically adjust the gain of the ADC sensor. . In addition, the density of the toner patch formed based on the reference light amount that forms the center of the exposure light may vary from the target value due to fluctuations in the developer charge amount due to changes in the ambient temperature and humidity. It is also necessary to periodically correct the reference light quantity that is indispensable for the adjustment of the image forming parameters that affect the above.
Therefore, preparation processing such as gain adjustment of the ADC sensor and correction of the reference light amount is generally performed when the environment changes greatly, such as when the power is turned off and the power is turned on after a long time has passed. is there.
[0004]
On the other hand, an electrophotographic image forming apparatus uses a fixing device that heats and pressurizes an unfixed toner image transferred onto a sheet to fix the toner image on the sheet. If this fuser is turned on after a long time since it was turned off, it takes time to warm up to a fixable temperature due to the temperature drop during that time, and printing cannot be started during that time. It is configured.
[0005]
Therefore, a technique for performing preparation processing necessary for the ADC system using this warm-up time is disclosed (Japanese Patent Publication No. 62-52872).
[0006]
According to this technique, there is an advantage that the preparation process can be performed efficiently.
[0007]
[Problems to be solved by the invention]
However, in the case of using the technique disclosed in Japanese Patent Publication No. 62-52872, in the image forming apparatus configured to drive the fixing device and the developing roll with the same main motor, the main motor is rotated immediately after the power is turned on for preparation processing. Therefore, the fixing device needs to start warming up while rotating a heating roll or the like.
[0008]
FIG. 1 is a flowchart showing the relationship between the warm-up of the fixing device and the preparation process for performing the ADC method.
[0009]
As shown in FIG. 1, when the power of the image forming apparatus is turned on, the heating roll of the fixing device (Fuser) starts rotating (S101) and the heat source lamp (Fuser Lamp) inside the heating roll is turned on. Then, warm-up is started (S203). At the same time, the photosensitive member (Drum) starts rotating (102), and ADC preparation processing (Procon Setup) is started (S104). When a predetermined time elapses and the preparation process (Procon Setup) ends (S105), the photosensitive member (Drum) stops rotating (106). The heating roll of the fixing device (Fuser) also stops rotating when a predetermined time elapses (S107). In the fixing device, the heat source lamp is lit even when the heating roll stops rotating, and the warm-up is continued, and when the temperature reaches a temperature at which the fixing device can be fixed (S108), The lamp (Fuser Lamp) is turned off (S109).
[0010]
FIG. 2 is a schematic diagram illustrating a temperature transition from when the power of the image forming apparatus is turned on until the fixing device reaches a temperature at which fixing can be performed.
[0011]
In FIG. 2, the vertical axis represents the fixing device temperature, and the horizontal axis represents the warm-up time from when the power is turned on to when the print is ready (Copy Standby). Below the horizontal axis, an image control unit (Procon control) that adjusts an image forming parameter that affects image density, a main motor (Main Motor) that drives a fixing device and a developing device, and a photoconductor are driven. The operation of a drum motor is shown.
[0012]
As shown in the figure, when the image forming apparatus is turned on, the main motor (Main Motor) rotates the fixing device (Fuser), and the drum motor (Drum Motor) rotates the photosensitive member (Drum). The image control unit (Procn control) starts a preparation process (Procon Setup). During this time, the fixing device (Fuser) rotates while the heating roll and the pressure roll are pressed against each other, so the heat of the heating roll heated by the heat source lamp (Fuser Lamp) is taken away by the rotating pressure roll. At the same time, heat dissipation is promoted by both rotations, so the temperature rise gradient of the fuser becomes gentle. When the predetermined time has elapsed, the main motor and the drum motor stop rotating, and the image control unit ends the preparation process. Also, if the main motor (Main Motor) stops rotating and the heating roll and pressure roll of the fuser (Fuser) stop rotating, the heat release from the rotation and the heat taken away by the pressure roll will decrease. The temperature increase gradient becomes larger than when the motor (Main Motor) is rotating.
[0013]
That is, if the time for rotating the main motor for the preparation process is long, there is a problem that the warm-up time of the fixing device is increased accordingly.
[0014]
In view of the above circumstances, the present invention increases the temperature rise gradient of the fixing device as much as possible, and reduces the warm-up time by reducing the time during which the temperature rise gradient is loosened by rotating the fixing device. An object is to provide an apparatus.
[0015]
[Means for Solving the Problems]
The image forming apparatus of the present invention that achieves the above object irradiates a photosensitive member rotating in a predetermined direction with exposure light to form an electrostatic latent image on the photosensitive member, carries toner on the surface, and faces the photosensitive member. Then, a developing device having a rotating developing roll applies toner to the electrostatic latent image to form a toner image on the photoconductor, and finally transfers the toner image onto a predetermined sheet. The toner image transferred onto the sheet is fixed on the sheet by a fixing device having a heating roll having a heat source therein and rotating in a predetermined direction and a pressure roll rotating in contact with the heating roll and rotating with the heating. In the image forming apparatus for forming an image composed of a fixed toner image on the paper,
A first motor for rotating the photoconductor;
A second motor that rotates both the heating roll and the developing roll;
A warm-up means for performing a warm-up to heat the fixing device to a predetermined warm-up temperature by energizing a heat source inside the heating roll in response to the power being supplied to the image forming apparatus;
A density sensor for measuring the density of the toner image is formed, a predetermined reference toner image is formed, the density of the reference toner image is measured by the density sensor, and the image forming apparatus is formed based on the measurement result. Image control means for adjusting image forming parameters that affect image density, and
The image control means uses the warm-up time by the warm-up means to first rotate the first motor and stop the rotation of the second motor before forming the reference toner image. A first measurement for measuring the density of the ground, and a second measurement for measuring the density of the reference toner image by forming the reference toner image in a state where the second motor is rotated together with the first motor. It is characterized by the fact that the measurement is performed.
[0016]
Here, after the warm-up of the fixing device by the warm-up means is started, the second motor is rotated, the end of the second measurement by the image control means, and a predetermined time. It is preferable to include a motor control means for stopping the rotation of the second motor in response to both progress.
[0017]
The image control means preferably starts the first measurement in response to the fixing device reaching a predetermined measurement start temperature.
[0018]
Furthermore, it is also preferable that the motor control means rotate the second motor in response to the fixing device reaching a predetermined motor rotation start temperature.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0020]
FIG. 3 is a schematic configuration diagram showing an embodiment of the image forming apparatus of the present invention.
[0021]
The image forming apparatus of the present embodiment shown in FIG. 3 has a photoreceptor 3 that rotates in the direction of arrow A. The photoreceptor 3 is uniformly charged by the charger 2, and the charged photoreceptor 3 is irradiated with exposure light from the laser exposure device 1 to form an electrostatic latent image. Toner is applied to the electrostatic latent image on the photoconductor 3 from a developing device 4 having a developing roll 16 that rotates in opposition to the photoconductor 3, and a toner image is formed on the photoconductor 3.
[0022]
The developing device 4 is connected to a toner container 14 in which toner is stored by a pipe 17, and a toner supply motor 15 is provided in the middle of the pipe 17. When the toner amount in the developing device 4 decreases, the toner supply motor 15 rotates to supply the toner in the toner container 14 into the developing device 4.
[0023]
A transfer belt device 7 that forms a transfer portion 5 between the photoconductor 3 and circulates in the direction of arrow B is disposed at a position in contact with the photoconductor 3 below the photoconductor 3. The transfer belt device 7 includes a transfer belt 6 that transfers a toner image on the photoreceptor 3 onto a sheet, a transfer device 18 that applies a bias voltage to the photoreceptor 3 via the transfer belt 6, and residual toner on the transfer belt. The belt cleaner 19 is a cleaning device. At the end of the transfer belt device 7 in the direction of arrow B, there is provided a fixing device 10 comprising a heating roll 10a and a pressure roll 10c to form a nip portion 10b. The heating roll 10a has a heat source lamp inside. The temperature sensor 10e for a heating roll for measuring the surface temperature is provided. The heat source lamp inside the heating roll 10a is energized by the warm-up means 24 when the power of the image forming apparatus is turned on, and the fixing device is warmed up to a temperature capable of fixing.
[0024]
The toner image formed on the photoreceptor 3 is transferred onto the paper, and the unfixed toner image on the paper is sandwiched between the nip portions 10b of the fixing device 10 and pressurized with heating, and is fixed on the paper. An image composed of a toner image is formed. After the toner image is transferred onto the transfer belt 6, the remaining toner is cleaned by the cleaner 11 and the residual charge is removed by the static eliminator 12 to complete one cycle.
[0025]
In this embodiment, both the developing roll 16 of the developing machine 4 and the heating roll 10a of the fixing device 10 are rotationally driven by a main motor (Main Motor) 20, and the photoreceptor 3 is rotationally driven by a drum motor (Drum Motor) 21. The The main motor 20 is controlled by the motor control means 23, starts rotating when the temperature of the fixing device reaches a predetermined motor rotation start temperature, and the predetermined temperature unevenness in the circumferential direction of the pressure roll 10c is improved. The rotation is stopped in response to both of the elapse of time and the end of the second measurement described later.
[0026]
In addition, the image forming apparatus includes an image control unit 22 that controls the density of an image to be formed. The image control unit 22 irradiates the photoconductor 3 with a reference light amount of exposure light, thereby generating a reference toner image. And the density of the reference toner image is measured by an ADC sensor 13 provided downstream of the transfer unit 5 in the direction of arrow A of the photoreceptor 3 and upstream of the cleaner 11. The image control unit 22 compares the measured density of the reference toner image with the target density, and adjusts the amount of exposure light emitted from the laser exposure device 1 to the photoconductor 3 according to the comparison result, thereby adjusting the sheet. Controls the density of the image formed on top. Since the ADC sensor 13 is provided downstream of the transfer unit 5, the reference toner image formed on the photoreceptor 3 can be moved to the measurement point of the ADC sensor 13 without being transferred by the transfer unit 5. When the reference toner image passes through the transfer unit 5, a bias voltage in the direction opposite to the normal direction is applied from the transfer unit 18.
[0027]
Here, the image forming parameters that affect the image density, such as the sensitivity of the photoreceptor 3 changing with temperature and the charge amount of the toner in the developing device 4 changing with temperature and humidity, are constantly changing depending on the surrounding environmental conditions. is doing. When the power is turned on and the image forming apparatus is operating, the image forming parameters are constantly adjusted by detecting temperature and humidity, and detecting the image density. Few. However, when the power is turned on after a long time has passed since the power was turned off, the sensitivity of the photoconductor 3 and the sensitivity of the ADC sensor 13 fluctuate greatly and deviate from the set image forming parameters. There is a high possibility that the control by the ADC system does not work well and the image quality is poor. Therefore, when the power is turned on after a long time has passed since the power was turned off, the image control unit 20 measures the density of the ground of the photoreceptor 3 and adjusts the gain of the ADC sensor based on the measurement result. Or measuring the density of the reference toner image formed on the photosensitive member 3 and adjusting the reference light quantity of the laser exposure device 1 based on the density.
[0028]
This preparation process can be specifically divided into two. One is to rotate the photosensitive member 3 but measure the density of the background on the surface of the photosensitive member 3 with the ADC sensor 13 without rotating the developing roll 16 of the developing machine 4 (first measurement) and the measurement. When the value deviates from the predetermined target value, this is a first preparation process for adjusting the gain of the ADC sensor 13. The other is to rotate the photosensitive member 3 and rotate the developing roller 16 of the developing device 4 to irradiate the photosensitive member 3 with a reference amount of exposure light to form a reference toner image and measure the density. (Second measurement) and the density of the reference toner image is compared with the target density. If the density is outside the target density, the second preparatory process for adjusting the reference light quantity irradiated from the laser exposure device 1 is performed. is there.
[0029]
Here, since the ADC sensor 13 of the present embodiment is provided downstream of the transfer unit 5 in the direction of the arrow A in which the photoconductor 3 rotates, when the reference toner image passes through the transfer unit 5, A bias voltage in the direction opposite to the normal direction is applied from the transfer unit 18 so as not to be transferred onto the recording medium. However, since the characteristics of the transfer device 18 vary greatly depending on the ambient temperature and humidity, the density of the reference toner image that has passed through the transfer unit 5 with the transfer belt 6 separated from the photoreceptor 3 is measured in the second preparation process. The measured density value is compared with the measured density value obtained by measuring the density of the reference toner image applied with the reverse bias from the transfer unit 18 and passed through the transfer unit 5, and whether or not the difference is within the allowable range. Check it out.
[0030]
FIG. 4 is a schematic perspective view showing a fixing device used in the image forming apparatus of the present embodiment.
[0031]
The fixing device 10 shown in FIG. 4 has a heat source lamp 10d inside, and a heating roll 10a rotating in the direction of arrow A, and the heating roll 10a is pressed against the nip portion 10b. The pressure roll 10c is formed and rotated in the same direction as the heating roll 10a. The surface of the heating roll 10a is equipped with a temperature sensor for heating roll (Sensor for Heat Roll) 10e, and the surface of the pressure roll (Presser Roll) 10c is equipped with a temperature sensor for pressure roll (Sensor for Presser Roll) 10f. Yes. An image composed of a fixed toner image is formed by heating and pressing a paper (paper) 25 to which an unfixed toner image is transferred in a nip portion 10b formed by the heating roll 10a and the pressure roll 10c.
[0032]
Since the heating roll 10a of the fixing device of this embodiment is thinned, the temperature rise gradient when the internal heat source lamp 10d is lit and heated is higher than that of the conventional heating roll having a large thickness. It is getting bigger.
[0033]
FIG. 5 is a schematic diagram showing a temperature rise pattern of the fixing device.
[0034]
In FIG. 5, the vertical axis represents the fixing device temperature, and the horizontal axis represents time. Further, below the horizontal axis, the operations of the image control unit (Procon control), the main motor (Main Motor), and the drum motor (Drum Motor) are shown.
[0035]
The dotted line (4) in the figure indicates that the heating roll is rotated until the preparation process (setup) by the image control unit is completed after the power is turned on. 3 shows a temperature rise pattern of the conventional fixing device shown in FIG.
[0036]
The solid line (3) shows the temperature rise pattern of the fixing device using the heating roll with a thin wall according to this embodiment, and the dotted lines (1) and (2) use a heating roll with a thin wall. Although this is a conventional fixing device, it is a comparative example in which the warm-up method is different from that of the fixing device of this embodiment.
[0037]
A dotted line {circle over (1)} shows a temperature rise pattern of the fixing device that performs the same warm-up method as the conventional example. The main motor is driven to rotate the heating roll and the pressure roll until the preparation process is completed after the power is turned on, and the rotation is stopped after the preparation process is completed. As is apparent from the comparison with the dotted line (4), the dotted line (1) shows that the temperature rise gradient of the fixing device is increased by the thickness of the heating roll, and the worm has been required for 3 minutes. The up time has been greatly reduced.
[0038]
The dotted line {circle over (2)} shows a temperature rise pattern of the fixing device in which the main motor is first stopped and warmed up, and the main motor is rotated after reaching a predetermined temperature. When the temperature of the fixing device reaches the second temperature and the main motor is driven to rotate the heating roll and the pressure roll, the preparation process is performed, and when the preparation process is completed, the rotation is stopped.
[0039]
Here, the fixing device conducts heat to the pressure roll through the nip portion, and when the heating roll and the pressure roll stop rotating, the heat is transferred from the heating roll to the pressure roll. Has a temperature distribution around the nip. Therefore, the dotted line (2) indicates that the heating roll and the pressure roll are rotated in order to improve the temperature unevenness generated in the circumferential direction of the pressure roll. The thermal efficiency is improved as compared with the dotted line (1).
[0040]
Also in the case of the dotted line (2), as in the case of the dotted line (1), the temperature rise gradient of the fixing device becomes large, and the warm-up time, which conventionally required 3 minutes, is greatly shortened.
[0041]
A solid line (3) indicates a temperature rise pattern of the fixing device used in the present embodiment.
[0042]
Although the temperature rise pattern is the same as that of the dotted line (2), the preparation process performed when the main motor is driven and the heating roll and the pressure roll are rotated is shortened, and the time for driving the main motor is shortened. Has been.
[0043]
In the present embodiment, the preparatory process of the image control unit is a first preparatory process (setup 1) performed while rotating the photoconductor but with the developing roll stopped, and rotating the photoconductor, the developing roll, and the heating roll. Is divided into second preparation processing (setup 2) performed by rotating the main motor with the main motor.
[0044]
The setup 1 starts warming up of the fixing device without rotating the heating roll even when the power is turned on. When the temperature of the fixing device reaches the first temperature, the temperature of the fixing device reaches the second temperature. Until the main motor is not rotated. The setup 2 is performed in a state where the heating roll is rotated when the temperature of the fixing device reaches the second temperature. Then, when the set-up 2 is completed and a predetermined time elapses in which the temperature unevenness in the circumferential direction of the pressure roll is improved by the rotation of the heating roll and the pressure roll of the fixing device, the main motor and the drum motor Stop rotation.
[0045]
Here, “elapse of a predetermined time” means until the fixing device completes the warm-up or before the fixing device completes the warm-up. Therefore, it may be defined by the required time based on the temperature characteristics of the fixing device, or may be defined by the required rotational speed.
[0046]
In solid line (3), setup 1 has already ended when warming up without rotating the main motor, so only setup 2 needs to be performed with the main motor rotated. is there. Therefore, the rotation time of the main motor can be shortened by the time for performing the setup 1 as compared with the dotted line (2).
[0047]
As described above, in the fixing device according to the present embodiment, the time from when the power is turned on to when the printer is ready for printing (Copy Standby) is shortened to about 30 seconds.
[0048]
FIG. 6 is a flowchart showing the relationship between the warm-up procedure of the fixing device by the warm-up means of the present embodiment and the preparation processing procedure by the image control unit.
[0049]
As shown in FIG. 6, when the power of the image forming apparatus is turned on, the warm-up means turns on the heat source lamp of the heating roll and starts warming up the fixing device (S201). When the temperature of the fixing device reaches the first temperature (S202), the image control unit rotates the photosensitive member (S203) and starts setup 1 (S204). When the setup 1 is completed (S206), and the temperature of the fixing device reaches the second temperature (S206), the warm-up means rotates the main motor to rotate the developing roll of the developing device and the heating roll of the fixing device. The rotation is driven (S207). The image control unit starts setup 2 (S209). When setup 2 is completed (S210), the rotation of the photosensitive member is stopped (S211). On the other hand, when the main motor starts rotating by the warm-up means, the heating roll and the pressure roll are idled for a predetermined time (S208), and the temperature unevenness in the circumferential direction of the pressure roll is improved (S212).
[0050]
Here, instead of idling the heating roll and the pressure roll for a predetermined time, the rotation may be stopped when the control unit finishes the setup 2, or the heating roll and the pressure roll are rotated a predetermined number of times. It can also be made.
[0051]
When the photosensitive member stops rotating and the setup 1 is completed, and the heating roll is idled for a predetermined time, the rotation of the main motor is stopped (S213). When the fixing device reaches a predetermined warm-up temperature (S214), the warm-up means turns off the heat source lamp of the heating roll (S215), and ends the predetermined warm-up.
[0052]
Next, the setup 1 will be described in detail.
[0053]
FIG. 7 is a flowchart illustrating a function of performing gain adjustment (AGC) of the ADC concentration sensor in the setup 1.
[0054]
As shown in FIG. 7, the image control unit rotates the photosensitive member (S301), sets a counter for counting the number of measurements to 1 (S302), and switches the gain value of the ADC sensor to a predetermined value (S303). The background density (Vclean) of the photoconductor is measured by the ADC sensor (S304). If the measured density (Vclean) is within the appropriate range, the ADC sensor outputs a normal value (S305), so the rotation of the photoconductor is stopped (S307), and AGC is terminated. However, if the measured density (Vclean) is not within the appropriate range, the counter of the number of times of measurement is set to 2 (S302), the gain value of the ADC sensor is switched (S303), and the background of the photoconductor is again detected by the ADC sensor. The concentration (Vclean) is measured (S304). If the measured density (Vclean) is not within the appropriate range (S305), the counter is further incremented, and the gain value of the ADC sensor is switched to measure the background density of the photoconductor. Repeat the process. If the measured density (Vclean) falls within the appropriate range (S305), the ADC sensor outputs normality, so the rotation of the photoconductor is stopped (S307), and the gain adjustment is terminated. However, when the counter value exceeds the predetermined number (S302), it is determined that adjustment is difficult by switching the gain of the ADC sensor, and the process proceeds to AGC fail processing (S306) and the rotation of the photosensitive member is stopped. (S307), AGC is terminated.
[0055]
In this preparation process, the sensitivity of the ADC sensor is adjusted by measuring the density (Vclean) of the background of the photoconductor. However, in the intermediate transfer body type image forming apparatus, the density of the ground of the photoconductor is adjusted. Alternatively, the sensitivity of the ADC sensor may be adjusted by measuring the background density of the intermediate transfer member.
[0056]
Note that the AGC fail process may be a process of, for example, stopping the control by the ADC method and switching to the control by only the ICDC method for predicting the toner consumption from the image signal.
[0057]
FIG. 8 is a flowchart for measuring the density (Vclean) of the ground of the photoconductor in the setup 1.
[0058]
As shown in FIG. 8, in the measurement of Vclean, first, the photosensitive member is rotated (S310), and the density on the surface of the photosensitive member is measured at regular intervals over the entire circumference by the ADC density sensor (S311). Then, it is determined whether or not the measured Vclean is within the proper range (S312). If the measured Vclean is within the proper range, the measurement of Vclean is terminated. After performing the Vclean fail processing which switches to only the processing (S313), the measurement of Vclean is terminated.
[0059]
Next, the setup 2 will be described in detail.
[0060]
FIG. 9 is a flowchart for correcting the exposure light amount in the setup 2.
[0061]
In FIG. 9, the density (Vclean) of the photoconductor ground measured in the setup 1 is read (S400). Then, the amount of light serving as a reference for the exposure light modulated based on the image data is set to the first exposure amount LD1 (S401). Next, the timer is reset to 0 (S402), the exposure light of the set first exposure amount LD1 is irradiated to the photosensitive member to form an electrostatic latent image, and developed with toner to fix the first toner patch. In step S403, the density of the first toner patch is measured by an ADC degree sensor to obtain a measured value Vpatch1 (S404). Next, the density Radc1 = C × (Vpatch1 / Vclean) of the first toner patch is obtained from the read density of the photoreceptor (Vclean) and the measured density value Vpatch1 of the first toner patch (S405). Here, C is a constant.
[0062]
Next, the obtained Radc1 is compared with the target density (S406).
[0063]
When Radc1 is equal to the target density, adjustment of the reference light amount is unnecessary, so the set first exposure amount LD1 is set as the reference light amount as it is (S416), and the light amount correction is completed.
[0064]
If Radc1 is larger than the target density, a difference ΔRadc = Radc1−Radc target value is calculated (S407).
If Radc1 is smaller than the target density, the difference ΔRadc = Radc target value−Radc1 is calculated (S408).
[0065]
Then, a corresponding correction amount is obtained from the calculated difference ΔRadc with reference to a table built in the image control unit (S409). Then, the correction amount is increased or decreased to the set first exposure amount LD1 to calculate a second exposure amount LD2 = LD1 ± correction amount (S410).
[0066]
Next, when the timer measures the rotation of one rotation of the photoconductor (S411), the corrected second exposure amount LD2 is irradiated to the same position where the first toner patch is formed, and developed with toner. Then, the second toner patch is formed (S412), and the density of the second toner patch is measured by the ADC sensor to obtain the measured value Vpatch2 (S413). Next, the density Radc2 = C × (Vpatch2 / Vclean) of the second toner patch is obtained from the read density (Vclean) of the photoreceptor and the measured density value Vpatch2 of the second toner patch (S414). Here, C is a constant.
[0067]
Next, interpolation is performed using the obtained Radc1 and Radc2, and an exposure amount calculation value for obtaining a target density = LD1 + (LD2-LD1) × (Radc target value−Radc1) / (Radc2−Radc1) is calculated. (S415). Then, the exposure amount calculation value is set as the reference light amount of the exposure light, and the light amount adjustment is completed.
[0068]
FIG. 10 is a flowchart in the setup 2 for checking the transfer state when the reference toner image (ADC patch) formed on the photosensitive member is passed through the transfer portion while being reverse-biased.
[0069]
In FIG. 10, the photosensitive member is first rotated (S421), the main motor is driven, and the developing roll of the developing machine is rotated (S422). Next, the transfer belt is separated from the photosensitive member (S423), and an ADC patch is repeatedly formed on the photosensitive member three times (S424). The density is measured by the ADC sensor, and the average value of the ADC patch density (ADC) (Separation) is calculated (S425). Next, the transfer belt is brought into contact with the photoreceptor (S426), and a reverse bias is applied to the transfer belt (S427). Then, an ADC patch is repeatedly created three times on the photoconductor (S428), its density is measured by the ADC sensor, and an average value (ADC contact) of the ADC patch density is calculated (S429). Next, a difference between the calculated average values of ADC patch densities (ADC contact and ADC separation) is obtained, and the difference is compared with a specified value (S430).
[0070]
If the difference (ADC contact-ADC separation) is smaller than the specified value as a result of the comparison, it is determined that the difference is normal (S430), the rotation of the photoconductor is stopped (S433), and the drive of the main motor is stopped (S434). ) To finish the check.
[0071]
However, when the difference is larger than the specified value, a secret failure is generated (S431), an ADC abnormal flag is set (S432), the rotation of the photosensitive member is stopped (S433), and the drive of the main motor is stopped (S433). S434), the check ends.
[0072]
When the ADC abnormal flag is set (S432), for example, the control by the ADC may be stopped and the control may be performed only by the ICDC.
[0073]
Here, in this flowchart, the density of the reference toner image is measured in a state where the transfer belt is separated from the photoconductor in order to obtain a normal value. However, it takes time to separate or contact the transfer belt. Therefore, in the normal time when the control by the ADC is performed, the density of the reference toner image is measured while the transfer belt is in contact with the photosensitive member.
[0074]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, it is possible to shorten the warm-up time of the fixing device and improve the warm-up efficiency. In addition, since the time for performing a series of image forming processes by rotating the photoconductor for ADC preparation processing can be shortened, the life of the photoconductor can be extended.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating a relationship between a warm-up of a fixing device and an advance preparation process of an ADC system.
FIG. 2 is a schematic diagram showing a change in fixing device temperature from when the image forming apparatus is turned on until the fixing device finishes warming up.
FIG. 3 is a schematic configuration diagram showing an embodiment of an image forming apparatus of the present invention.
FIG. 4 is a schematic perspective view illustrating a fixing device of the image forming apparatus according to the exemplary embodiment.
FIG. 5 is a schematic diagram showing a temperature rise pattern of the fixing device.
FIG. 6 is a flowchart showing the relationship between the warm-up procedure of the fixing device by the warm-up means of the present embodiment and the preparation processing procedure by the image controller.
FIG. 7 is a flowchart of ADC sensor gain adjustment (AGC) in setup 1;
FIG. 8 is a flowchart for measuring the density (Vclean) of the background of the photosensitive member in the setup 1;
FIG. 9 is a flowchart for correcting the exposure light amount in the setup 2;
FIG. 10 is a flowchart for checking a transfer state when a reference toner image (ADC patch) formed on a photoconductor is passed through a transfer portion while applying a reverse bias in the setup 2;
[Explanation of symbols]
1 Laser exposure tool
2 Charger
3 Photoconductor
4 Developer
5 Transfer section
6 Transfer belt
7 Transfer belt device
9 Transfer auxiliary charger
10 Fixing device
10a Heating roll
10b Nip part
10c Pressure roll
10d Lamp for heat source
10e Temperature sensor for heating roll
10f Temperature sensor for pressure roll
11 Cleaner
12 Static eliminator
13 ADC sensor
14 Toner container
15 Toner supply motor
16 Development roll
17 Pipe
18 Transfer device
19 Belt cleaner
20 Main motor
21 Drum motor
22 Image controller
23 Motor control means
24 Warm-up means
25 paper

Claims (4)

The photosensitive member rotating in a predetermined direction is irradiated with exposure light to form an electrostatic latent image on the photosensitive member, and the static electricity is developed by a developing device having a developing roll that carries toner on the surface and rotates opposite the photosensitive member. Toner is applied to the electrostatic latent image to form a toner image on the photoreceptor, the toner image is finally transferred onto a predetermined paper, and the toner image transferred onto the paper has a heat source inside. Then, a fixing device having a heating roll rotating in a predetermined direction and a pressure roll rotating in contact with the heating roll and rotating together with the heating is fixed on the paper, and an image composed of a fixing toner image is formed on the paper. In the image forming apparatus to be formed,
A first motor for rotating the photoreceptor;
A second motor that rotates both the heating roll and the developing roll;
A warm-up means for performing a warm-up to heat the fixing device to a predetermined warm-up temperature by energizing a heat source inside the heating roll in response to the power being supplied to the image forming apparatus;
A density sensor for measuring the density of the toner image is formed, a predetermined reference toner image is formed, the density of the reference toner image is measured by the density sensor, and the image forming apparatus is formed based on the measurement result. Image control means for adjusting image forming parameters that affect image density, and
The image control means uses the warm-up time by the warm-up means to first rotate the first motor and stop the rotation of the second motor before forming the reference toner image. A first measurement for measuring the density of the ground, and a second measurement for measuring the density of the reference toner image by forming the reference toner image in a state where the second motor is rotated together with the first motor. An image forming apparatus for measuring After the warm-up of the fixing device by the warm-up means is started, the second motor is rotated, and the end of the second measurement by the image control means and the elapse of a predetermined time period. The image forming apparatus according to claim 1, further comprising a motor control unit that receives both of them and stops the rotation of the second motor. The image forming apparatus according to claim 1, wherein the image control unit starts the first measurement when the fixing device reaches a predetermined measurement start temperature. The image forming apparatus according to claim 1, wherein the motor control unit rotates the second motor in response to the fixing unit reaching a predetermined motor rotation start temperature.

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