JP2021157127A - Calibration method - Google Patents

Abstract

To shorten time required for calibration.SOLUTION: A calibration method includes steps of: acquiring a first light receiving sensor output value to determine whether the value is equal to or larger than a white determination minimum threshold value or more; when the light receiving sensor output value is equal to or larger than the white determination minimum threshold value, acquiring a second light receiving sensor output value on a detection region moving direction side from a position of a detection region where the first light receiving sensor output value is obtained to determine whether the value is equal to or larger than the white determination minimum threshold value; when the second light receiving sensor output value is the white determination minimum threshold value, provisionally determining that a detection region is located inside a white region AW; acquiring a third light receiving sensor output value on a detection region moving direction side from the position of the detection region where the second light receiving sensor output value is obtained to determine whether the value is equal to or larger than the white determination minimum threshold value; and when the third light receiving sensor output value is equal to or larger than the white determination minimum threshold value, determining that the detection region is positioned inside the white region when the second light receiving sensor output value is acquired.SELECTED DRAWING: Figure 10

Description

The present invention relates to a calibration method, and is suitable for application to, for example, an electrophotographic printer (hereinafter, this is also simply referred to as a printer).

The electrophotographic image forming apparatus transfers the developing agent image formed by the developing agent to a medium such as paper, and then fixes the developing agent image on the medium by a fixing device.

Some fusers included in such an image forming apparatus include a heating roller, a pressure roller, and a heating member arranged inside the heating roller. The fuser rotates while bringing the heating roller and the pressure roller into contact with each other, and heats and pressurizes the conveyed medium by sandwiching it between the nip portions formed between the heating roller and the pressure roller. , The developer image on the medium is heated and melted and fixed on the medium.

In such a fuser, a pressing mechanism or the like for forming a nip portion between the heating roller and the pressurizing roller is provided by pressing the pressurizing roller against the heating roller with a predetermined nip pressure. Further, the fuser is provided with an eccentric cam in the pressing mechanism that moves a pressure roller to form or release a nip portion. Further, in the fuser, the eccentric cam is rotated by driving the fixing motor and stopped at a predetermined position to form a nip portion and adjust the nip pressure (see, for example, Patent Document 1).

In addition, the fuser has a reflector that rotates with the eccentric cam, and the reflected light is received by the light receiving sensor, and the rotation position of the eccentric cam is detected based on the intensity of the reflected light. Some control the formation or release. Such light receiving sensors need to be calibrated when they are put into use.

Japanese Unexamined Patent Publication No. 2020-16734

In such an image forming apparatus, it is desired to reduce the time required for calibration.

The present invention has been made in consideration of the above points, and an object of the present invention is to propose a calibration method capable of shortening the time required for calibration.

In order to solve such a problem, in the calibration method of the present invention, a predetermined current flows through a reflector in which a first reflection region and a second reflection region having different light reflectances are formed along the rotation direction. A light emitting unit that emits light and irradiates the detection area at a predetermined position on the reflector with emitted light, a light receiving sensor that receives the reflected light reflected by the emitted light in the detection region of the reflecting plate and outputs a light receiving sensor output value, and a light receiving sensor. In the calibration method in the rotation position detection mechanism having a control unit that detects the rotation position of the reflector based on the change in the sensor output value, the first light receiving sensor output value is acquired, and at least a part of the detection area is the first reflection. When the first light receiving sensor output value acquisition determination step for determining whether or not it is equal to or higher than the first reflection region judgment threshold when it is included in the region and the first light receiving sensor output value is equal to or higher than the first reflection region judgment threshold. The second light receiving sensor output value is acquired on the detection area moving direction side from the position of the detection area where the first light receiving sensor output value is acquired, and it is determined whether or not it is equal to or greater than the first reflection area determination threshold. When the second light receiving sensor output value acquisition determination step and the second light receiving sensor output value are equal to or higher than the first reflection area judgment threshold, it is tentatively determined that the detection area is located inside the first reflection area, and the second time. The first reflection region provisional determination step for storing the light receiving sensor output value and the third light receiving sensor output value are acquired on the detection region moving direction side from the position of the detection region where the second light receiving sensor output value is acquired, and the third. 1st light receiving sensor output value acquisition judgment step to judge whether or not it is equal to or more than the 1 reflection area judgment threshold, and 2nd light receiving sensor output when the 3rd light receiving sensor output value is equal to or more than the 1st reflection area judgment threshold Calibration to calibrate the light receiving sensor based on the first reflection area determination step, which determines that the detection area was located inside the first reflection area when the value is acquired, and at least the second light receiving sensor output value. Made to have steps and.

Further, in the calibration method of the present invention, a reflecting plate in which a first reflecting region and a second reflecting region having different light reflectances differ from each other along the rotation direction and a reflecting plate in which a predetermined current is passed to emit light are emitted. A light emitting unit that irradiates the detection area at a predetermined position with the emitted light, a light receiving sensor that receives the reflected light reflected by the emitted light in the detection area of the reflector and outputs the light receiving sensor output value, and a change in the light receiving sensor output value. In the calibration method in the rotation position detection mechanism having the control unit for detecting the rotation position of the reflector based on the above, when the first light receiving sensor output value is acquired and at least a part of the detection area is included in the first reflection area. The first light receiving sensor output value acquisition judgment step for determining whether or not it is equal to or more than the first reflection area judgment threshold of The first light receiving sensor output value storage step for storing the sensor output value and the second light receiving sensor output value acquired in the detection area moving direction from the position of the detection area where the first light receiving sensor output value was acquired are obtained, and the first The second light receiving sensor output value acquisition judgment step for determining whether or not it is equal to or higher than the reflection area judgment threshold, and the second light receiving sensor output value when the second light receiving sensor output value is equal to or higher than the first reflection area judgment threshold. When the second light receiving sensor output value storage step for storing the above, the first light receiving sensor output value and the second light receiving sensor output value are compared, and the light receiving sensor output value having the larger value is acquired, the detection area Calibration of the light receiving sensor based on the first reflection area determination step for determining that was located inside the first reflection area and at least the light receiving sensor output value determined that the detection area was located inside the first reflection area. To have a calibration step to perform.

Thereby, the present invention is calibrated as compared with the case where the change point from the second reflection region to the first reflection region of the detection region is detected and then the detection region is determined to be located inside the first reflection region. The output value of the light receiving sensor in the first reflection region used for the operation can be quickly determined.

According to the present invention, calibration is performed as compared with the case where the change point from the second reflection region to the first reflection region of the detection region is detected and then the detection region is determined to be located inside the first reflection region. It is possible to realize a calibration method in which the output value of the light receiving sensor in the first reflection region used for calibration can be quickly determined and the time required for calibration can be shortened.

It is a left side view which shows the structure of the image forming apparatus. It is a block diagram which shows the control structure of an image forming apparatus. It is a figure which shows the structure of the rotation position detection mechanism. It is a flowchart which shows the calibration processing procedure (1) by 1st Embodiment. It is a flowchart which shows the calibration processing procedure (2) by 1st Embodiment. It is a flowchart which shows the calibration processing procedure of the comparative example. It is a figure which shows the change of the detection position when all the light-receiving sensor output values are equal to or more than the white judgment minimum threshold value in three times light-receiving sensor output detection operation. It is a figure which shows the change of the detection position when the light-receiving sensor output value is less than the white judgment minimum threshold value in the 3rd light-receiving sensor output detection operation. It is a figure which shows the change of the detection position in the comparative example. It is a time chart which shows the light-receiving sensor output value when all the light-receiving sensor output values are equal to or more than the white judgment minimum threshold value in three times light-receiving sensor output detection operation. It is a time chart which shows the light-receiving sensor output value when the light-receiving sensor output value is less than the white judgment minimum threshold value in the 3rd light-receiving sensor output detection operation. It is a time chart which shows the light receiving sensor output value in the comparative example. It is a block diagram which shows the functional structure in the fixation release sensor calibration control part by 1st Embodiment. It is a flowchart which shows the calibration processing procedure (1) by 2nd Embodiment. It is a flowchart which shows the calibration processing procedure (2) by 2nd Embodiment. It is a time chart which shows the light receiving sensor output value by 2nd Embodiment. It is a block diagram which shows the functional structure in the fixation release sensor calibration control part by 2nd Embodiment.

Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[1. First Embodiment]
[1-1. Internal configuration of image forming apparatus]
As shown in FIG. 1, the image forming apparatus 1 is an electrophotographic printer and has a substantially box-shaped apparatus housing 2. Here, the right side in the drawing of the device housing 2 is the front surface, the left side in the drawing is the rear surface, the direction from the front surface to the rear surface of the device housing 2 is the rear direction, the direction from the rear surface to the front surface is the front direction, and the device housing 2 The direction from the lower side to the upper side is upward, the direction from the upper side to the lower side of the device housing 2 is downward, the direction from the front side to the back side in the figure of the device housing 2 is the right direction, and the device housing. The direction from the back side to the front side in the figure of 2 is the left direction. Further, in the following, the direction in which the paper P travels is referred to as a transport direction, and the left-right direction orthogonal to the transport direction and the thickness direction of the paper P is referred to as a transport width direction.

Inside the device housing 2, there are four color toners (for example, black (K), yellow (Y), magenta (M), and cyan (C)) that are handled by the image forming device 1 on the upper part. ), And four image forming units 3 (3K, 3Y, 3M, and 3C) corresponding to each of) are provided side by side in the front-rear direction along the transport path R of the paper P.

Each image forming unit 3 (3K, 3Y, 3M and 3C) has a photoconductor drum 4 (4K, 4Y, 4M and 4C) and a toner cartridge 5 (5K, 5Y, 5M and 5C). Each image forming unit 3 (3K, 3Y, 3M and 3C) irradiates and exposes the surface of the photoconductor drum 4 (4K, 4Y, 4M and 4C) with light to expose the photoconductor drum 4 (4K, 4Y, After forming an electrostatic latent image on the surface of 4M and 4C), the toner supplied from the toner cartridge 5 (5K, 5Y, 5M and 5C) is attached to the electrostatic latent image to cause the photoconductor drum 4 (5K, 5Y, 5M and 5C). A toner image is formed on the surface of 4K, 4Y, 4M and 4C).

Further, inside the apparatus housing 2, a transfer unit 6 is provided below the image forming unit 3 (3K, 3Y, 3M and 3C). The transfer unit 6 is located below the photoconductor drum 4 (4K, 4Y, 4M, and 4C) with the annular transport belt 7 arranged so as to travel rearward along the transport path R and the transport belt 7 in between. It has transfer rollers 8 (8K, 8Y, 8M and 8C) arranged to face each other.

The transfer roller 8 (8K, 8Y, 8M and 8C) reverses the paper P to the toner when the paper P passes between the photoconductor drum 4 (4K, 4Y, 4M and 4C) and the transport belt 7. By charging the paper to a polarity, the toner image of each color formed on the photoconductor drum 4 (4K, 4Y, 4M and 4C) is transferred to the paper P.

Further, a tray 9 for accommodating the paper P is provided below the transfer unit 6 at the lower part inside the apparatus housing 2. In the vicinity of the tray 9, a hopping roller 10 is provided to feed the paper P housed in the tray 9 one by one to the transport path R. Further, inside the apparatus housing 2, a transport roller or the like for transporting the paper P is provided on the transport path R between the tray 9 and the transfer unit 6.

Further, inside the apparatus housing 2, a fixing device 11 is provided on the rear side, which is the downstream side in the transport direction of the paper P with respect to the transfer unit 6. The fuser 11 has an upper heating roller 16 and a lower pressure roller 18, and when the paper P passes through a nip portion formed between the heating roller 16 and the pressure roller 18. By heating and pressurizing the paper P, the toner image is fixed on the paper P. The heating roller 16 is rotatably supported by an upper frame (not shown) on the upper side of the transport path R, and a heating member is fixed inside. The heating roller 16 is rotated along with the rotation of the pressure roller 18.

The pressure roller 18 is rotatably supported by a lower frame (not shown) so as to face the heating roller 16 vertically on the lower side of the transport path R. The pressurizing roller 18 rotates by transmitting the driving force of the fixing motor (not shown) rotating in the forward rotation direction. The lower frame is rotatably supported by the upper frame. Further, an eccentric cam (not shown) fixed to a shaft (not shown) and rotating with the shaft is in contact with the lower frame. This shaft rotates by transmitting the driving force of the fixing motor rotating in the reverse direction opposite to the forward rotation direction. Therefore, when the fixing motor rotates in the reverse direction and the eccentric cam rotates, the lower frame rotates according to the portion of the outer peripheral portion of the eccentric cam that abuts on the lower frame.

An urging member, which is a compression spring, is installed between the upper frame and the lower frame, and the lower side is rotated in the pressing rotation direction, which is the direction in which the pressure roller 18 is pressed against the heating roller 16. The frame is being urged. Therefore, the pressure roller 18 is pressed against the heating roller 16 by the urging force of the urging member with an arbitrary pressure via the lower frame. At this time, a nip portion is formed between the heating roller 16 and the pressure roller 18. The state in which the pressure roller 18 is pressed by the heating roller 16 in this way is also referred to as a nip state. In this nip state, the fixing device 11 fixes the toner image on the paper P by heating and pressurizing the paper P at the nip portion when the paper P passes through.

On the other hand, when the lower frame rotates in the direction of separation rotation in the direction opposite to the pressing rotation direction from the nip state, the pressure roller 18 moves in the direction away from the heating roller 16 as compared with the nip state. The nip formation between the pressurizing roller 18 and the heating roller 16 is released. In the following, a state in which the pressure roller 18 is separated from the heating roller 16 and the heating roller 16 is not pressed by the pressure roller 18 is also referred to as a release state.

In this way, the image forming apparatus 1 rotates the fixing motor in the forward rotation direction to rotate the pressurizing roller 18 and the heating roller 16 to convey the paper P, while rotating the fixing motor in the reverse direction. Rotate the shaft and eccentric cam to form or eliminate the nip.

Further, a stacker 12 for ejecting the paper P is provided at the upper end of the device housing 2. Further, inside the apparatus housing 2, discharge rollers and the like for discharging the paper P to the stacker 12 are provided on the transport path R between the fixing device 11 and the stacker 12. Further, inside the device housing 2, medium detection sensors and the like for detecting the paper P are provided at a plurality of locations on the transport path R.

In such a configuration, the image forming apparatus 1 feeds the paper P housed in the tray 9 one by one into the transport path R by the hopping roller 10. The paper P fed out to the transfer path R is conveyed to the transfer unit 6, and is sequentially conveyed to the image forming units 3K, 3Y, 3M, and 3C by the transfer belt 7 of the transfer unit 6. Here, the image forming units 3K, 3Y, 3M and 3C form toner images of each color on the surfaces of the photoconductor drums 4K, 4Y, 4M and 4C. The toner images thus formed on the surfaces of the photoconductor drums 4K, 4Y, 4M and 4C are transferred onto the paper P by the transfer rollers 8K, 8Y, 8M and 8C, whereby the color is transferred onto the paper P. A toner image is formed.

The paper P on which the color toner image is formed is conveyed from the transfer unit 6 to the fixing device 11. The fixer 11 fixes the color toner image on the paper P. As a result, the color image is printed on the paper P. After that, the paper P is conveyed to the stacker 12 and discharged onto the stacker 12.

[1-2. Control configuration of image forming device]
As shown in FIG. 2, the image forming apparatus 1 includes a system control unit 20, a connection I / F unit 22, an image data storage unit 24, a print control unit 26, a medium paper feed control unit 28, a medium transfer control unit 30, and a fixing release. It is composed of a sensor calibration control unit 32, a fixing control unit 34, an operation display unit 36, and a memory unit 38. The system control unit 20 is composed of a CPU (Central Processing Unit) and a RAM (Random Access Memory), and controls and controls the entire image forming apparatus 1 based on a control program stored in a storage unit (not shown). .. Further, the system control unit 20 acquires a command reception result from the connection I / F unit 22 and activates the print control unit 26 and the operation display unit 36 to execute the process. Further, the system control unit 20 stores the image data received via the connection I / F unit 22 in the image data storage unit 24.

The connection I / F unit 22 connects to a LAN (Local Area Network) line, for example, and performs TCP / IP control to perform data communication with a higher-level device connected by the LAN. The image data storage unit 24 is a hard disk built in the image forming device 1 and stores print data received from the host device.

The print control unit 26 controls the printing operation, and activates the medium paper feed control unit 28 and the medium transfer control unit 30 to execute printing. The medium paper feed control unit 28 controls the paper feed from the tray 9 when performing the printing operation. The medium transfer control unit 30 controls the transfer of the paper P when performing the printing operation.

The fixing release sensor calibration control unit 32 calibrates the rotation position detection mechanism 50 shown in FIG. In the calibration of the rotation position detection mechanism 50, the fixing release sensor calibration control unit 32 rotates the reflecting plate 56 while irradiating the reflecting plate 56 shown in FIG. 3 of the fixing device 11 with light from the light emitting unit 52, and the reflected light thereof. The amount of light of the light emitting unit 52 is adjusted according to the result of receiving the light.

The fixing control unit 34 controls the fixing device 11 such as temperature control of the heating roller 16 for fixing the toner on the paper P and drive control of the fixing motor inside the fixing device 11.

The operation display unit 36 is installed so that the user can operate it in a part of the device housing 2 of the image forming apparatus 1, and a menu key for the user to operate the image forming apparatus 1 and a user can operate the operation display unit 36. It has an operation unit consisting of a setting key for determining and starting an operation, a cancel key for the user to stop the operation, and a display unit for displaying various information such as input information and alarm information. doing.

The memory unit 38 is a volatile storage device and stores data used by the image forming device 1. The memory unit 38 indicates a heating width range corresponding to the width in the transport width direction of the paper P in the print control data storage unit 40 for storing data related to print control and the heating member inside the heating roller 16 of the fixing device 11. It includes a fixing temperature width setting storage unit 42 for storing information.

[1-3. Configuration of rotation position detection mechanism]
As shown in FIG. 3, the rotation position detection mechanism 50 includes a fixing release sensor calibration control unit 32 (FIG. 2), a light emitting unit 52, a light receiving sensor 54, and a reflector 56.

The light emitting unit 52 is composed of, for example, an LED (Light Emitting Diode), and the LED current value, which is the current value to be passed, is controlled based on the control of the fixing release sensor calibration control unit 32, and emits emitted light. The detection region AD fixed at a predetermined position on the reflector 56 is irradiated. The light receiving sensor 54 is an analog sensor, receives the reflected light reflected by the emitted light in the detection region AD of the reflecting plate 56, converts the light receiving level into analog digital conversion, and as a result of the detection, the fixing release sensor calibration control unit 32 And transmission to the fixing control unit 34. The light receiving sensor 54 needs to be calibrated to determine the black and white threshold value in detecting the rotational position of the eccentric cam. The black-and-white threshold value determines whether the light-receiving sensor output value, which is the detection result of the light-receiving sensor 54, is the value when the detection area AD is located in the white area AW or the black area AB (described later). It is for doing.

The reflector 56 has a thin disk shape, is fixed to the shaft, and rotates around the central axis in the reflector rotation direction r1 in conjunction with the shaft. In the reflector 56, a white white region AW is formed over a wide rotation angle range of 290 [°] out of a rotation angle of 360 [°] along the circumferential direction which is the rotation direction. Therefore, a black fan-shaped black region AB is formed over a rotation angle range of 70 [°], which is a narrow rotation angle range. The rotation angle range occupied by the black region AB with respect to the reflector 56 is also referred to as a black region occupation angle range. This black area occupancy angle range corresponds to the range of the nip portion. The boundary where the reflector 56 rotates in the reflector rotation direction r1 and the detection region AD transitions from the white region AW to the black region AB is also called a black-and-white boundary BDwb, and the detection region AD transitions from the black region AB to the white region AW. The boundary is also called a black-and-white boundary BDbw. Hereinafter, the black-and-white boundary BDwb and the black-and-white boundary BDbw are also collectively referred to as a boundary BD.

The black-and-white boundary BDwb is irradiated by the light emitting unit 52 as the reflector 56 rotates in the reflector rotation direction r1, that is, when the detection region AD is located at the black-and-white boundary BDwb, the detection region AD is located at the white region AW. The intensity of the reflected light received by the light receiving sensor 54 becomes lower and the output value of the light receiving sensor becomes smaller than in the case where the light receiving sensor 54 receives light. After that, the black-and-white boundary BDbw is irradiated by the light emitting unit 52 as the reflector 56 rotates in the reflector rotation direction r1, that is, when the detection area AD is located at the black-and-white boundary BDbw, the detection area AD becomes the black area AB. Compared with the case where the light receiving sensor 54 is located, the intensity of the reflected light received by the light receiving sensor 54 is increased, and the output value of the light receiving sensor is increased.

The fixing release sensor calibration control unit 32 and the fixing control unit 34 determine whether or not the black-and-white boundary BDwb or the black-and-white boundary BDbw on the reflector 56 is irradiated by the light emitting unit 52 based on the detection result received from the light receiving sensor 54. Detects the position of the eccentric cam in the rotation direction, that is, the rotation position. In this way, the image forming apparatus 1 detects whether the state of the nip portion is the nip state or the release state by detecting the rotation position of the eccentric cam by the reflector 56.

[1-4. About calibration]
The calibration is a process of determining a black-and-white threshold value of the light receiving sensor output value for determining whether the detection region AD is located in the white region AW or the black region AB. In order to determine this black-and-white threshold, the LED current value, white level and black level need to be determined.

In the calibration, the image forming apparatus 1 first determines the LED current value and the white level in a state where the detection region AD is surely inside the white region AW of the reflector 56. The white level is a light receiving sensor output value when the LED current value is increased while the detection region AD is in the white region AW and the light receiving sensor output value is saturated. The LED current value is the current value flowing through the light emitting unit 52 at that time. Next, the image forming apparatus 1 determines the black level in a state where the detection region AD is surely inside the black region AB in the reflector 56. The black level is a light receiving sensor output value in a state where the detection region AD is in the black region AB. Next, the image forming apparatus 1 calculates an average value of the white level and the black level and sets it as a black-and-white threshold value. The reason for first determining the LED current value and the white level is to determine whether or not the light receiving sensor output value is saturated when the detection region AD is inside the white region AW of the reflector 56, and the LED at that time. This is because the current value is used as a reference.

Here, the detection area AD (that is, the sense area of the light receiving sensor 54) has a range having a certain area, not a point. Therefore, when the light receiving sensor output detection operation for detecting the light receiving sensor output value of the light receiving sensor 54 is performed, the detection area AD may overlap the boundary BD and straddle both the white area AW and the black area AB. .. In that case, the light receiving sensor output value is higher than when the detection region AD is completely inside the black region AB, but it is not possible to determine how much the detection region AD is inside the white region AW.

Therefore, even if the image forming apparatus 1 detects the light receiving sensor output value when performing the light receiving sensor output detecting operation, it can determine whether or not the detection area AD is completely in the black area AB, but the detection area It cannot be easily determined whether the AD overlaps the boundary BD or the detection region AD is completely in the white region AW. Therefore, when performing calibration, the image forming apparatus 1 determines that the detection area AD has passed the boundary BD in order to perform the light receiving sensor output detection operation in a state where the detection area AD does not overlap the boundary BD. Then, after waiting for the measurement standby time Tms, for example, 100 [ms], the light receiving sensor output value is detected. The reflector 56 rotates in the reflector rotation direction r1 by the rotation angle of 13 [°], which is the standby rotation angle, during the measurement standby time Tms of 100 [ms].

Here, the light receiving sensor output value in a state where the detection region AD is completely contained in the black region AB is, for example, 0.5 [V], and when the detection region AD is located at the boundary BD or in the white region AW. It is clearly lower than the output value of the light receiving sensor when it is completely in. Therefore, when the image forming apparatus 1 acquires the light receiving sensor output value of 0.5 [V], it can be determined that the detection region AD is completely included in the black region AB.

Further, with respect to FIGS. 7, 8 and 9, the reflector 56 rotates in the reflector rotation direction r1 in a state where the detection position, which is originally the position of the detection region AD, is constant, but for convenience of explanation, the reflector 56 The state in which the detection region AD moves with respect to the reflector 56 as it rotates in the reflector rotation direction r1 is shown as a state in which the reflector 56 is fixed and the detection region AD moves. Therefore, the detection region AD moves toward the detection region movement direction ra1 as the reflector 56 rotates in the reflector rotation direction r1.

[1-5. Calibration process]
The specific processing procedure of the calibration process by the image forming apparatus 1 will be described with reference to the flowcharts of FIGS. 4 and 5. The fixing release sensor calibration control unit 32 starts the calibration processing procedure RT1 by reading the calibration processing program from the storage unit and executing it, and proceeds to step SP1.

[When all the light receiving sensor output values are equal to or higher than the white judgment minimum threshold value in 1-5 to 1.3 times of the light receiving sensor output detection operation]
First, FIG. 4 describes a specific processing procedure of the calibration process by the image forming apparatus 1 when all the light receiving sensor output values are equal to or higher than the white judgment minimum threshold value THwl in the three light receiving sensor output detection operations described later. And the flowchart of FIG. 5, the detection position shown in FIG. 7, and the timing chart of the light receiving sensor output value shown in FIG. 10 will be described. At this time, it is assumed that the detection area AD is located at the detection start position ps1 in FIG.

In step SP1, the fixing release sensor calibration control unit 32 starts the rotation of the reflector 56 and moves to step SP2. In step SP2, the fixing release sensor calibration control unit 32 performs the first light receiving sensor output detection operation at the time point t1 in FIG. 10, and proceeds to step SP3. In this first light receiving sensor output detection operation, the fixing release sensor calibration control unit 32 acquires the light receiving sensor output value from the light receiving sensor 54. At this time, it is assumed that the detection area AD is located at the detection position p1 in FIG. 7.

In step SP3, the fixing release sensor calibration control unit 32 determines whether or not the light receiving sensor output value is equal to or greater than the white determination minimum threshold value THwl at the time point t1 in FIG. The white determination minimum threshold value THwl is the minimum light receiving sensor output value at which it is determined that the detection region AD is located at a location including the white region AW, and is 1.5 [V]. If a positive result is obtained here, this means that the current detection region AD is not located at least completely inside the black region AB, although it may partially contain the black region AB. A part thereof indicates that it is located inside the white region AW, and at this time, the fixing release sensor calibration control unit 32 moves to step SP4. On the other hand, if a negative result is obtained in step SP3, this means that the current detection region AD is completely located inside the black region AB, and at this time, the fixing release sensor calibration control unit 32 is in step SP17. Move on to (Fig. 5).

In step SP4, the fixing release sensor calibration control unit 32 waits for the measurement standby time Tms at the time point t2 in FIG. The state is set to be located inside the white region AW apart from the above, and the process proceeds to step SP5. At this time, the detection area AD is located at the detection position p2 in FIG. 7.

In step SP5, the fixing release sensor calibration control unit 32 performs the second light receiving sensor output detection operation at the time point t3 in FIG. 10, and proceeds to step SP6. In this second light receiving sensor output detection operation, the fixing release sensor calibration control unit 32 acquires the light receiving sensor output value from the light receiving sensor 54. At this time, the detection area AD is located at the detection position p3 in FIG. 7.

In step SP6, the fixing release sensor calibration control unit 32 determines whether or not the light receiving sensor output value is equal to or greater than the white determination minimum threshold value THwl at the time point t3 in FIG. If an affirmative result is obtained here, this means that the detection area AD is located on the black-white boundary BDbw or on the detection area moving direction ra1 side of the black-white boundary BDbw during the first light receiving sensor output detection operation. Therefore, although the current detection area AD may be located at the black-and-white boundary BDwb, it is highly likely that it is located inside the completely white area AW. At this time, the fixing release sensor calibration control The unit 32 moves to step SP7. On the other hand, when a negative result is obtained in step SP6, this means that the detection area AD was located at the black-and-white boundary BDwb during the first light receiving sensor output detection operation, so that the current detection area AD is completely inside the black area AB. At this time, the fixing release sensor calibration control unit 32 moves to step SP17 (FIG. 5).

In step SP7, the fixing release sensor calibration control unit 32 gradually increases the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws at the time point t3 in FIG. 10, and proceeds to step SP8. The white saturation threshold THws is 3.1 [V]. The fixing release sensor calibration control unit 32 waits 5 [ms] after increasing the current by a predetermined amount of current increase, and while confirming that the light receiving sensor output value is increasing, the light receiving sensor output value is white. The LED current value is gradually increased until the saturation threshold THws or more is reached. For example, when the image forming apparatus 1 raises the light receiving sensor output value by 0.5 [V] according to the amount of current increase at one time, and when the current light receiving sensor output value is 2.1 [V], it is 2 The current is increased stepwise only once. As a result, the output value of the light receiving sensor becomes 3.1 [V].

In step SP8, the fixing release sensor calibration control unit 32 temporarily determines the LED current value and the white level in the second light receiving sensor output detection operation at the time point t3 in FIG. 10, and stores them in the memory unit 38, and in step SP9. Move to. This white level is the current output value of the light receiving sensor.

In step SP9, the fixing release sensor calibration control unit 32 lowers the once increased LED current value to the value at the start of calibration at the time point t4 in FIG. 10, and waits for the measurement standby time Tms for the second time. The detection area AD in the light receiving sensor output detection operation is located inside the white area AW away from the black-and-white boundary BDwb by the standby rotation angle or more toward the detection area movement direction ra1, and the process proceeds to step SP10 (FIG. 5). At this time, the detection area AD is located at the detection position p4 in FIG. 7.

In step SP10, the fixing release sensor calibration control unit 32 performs the third light receiving sensor output detection operation at the time point t5 in FIG. 10, and proceeds to step SP11. In this third light receiving sensor output detection operation, the fixing release sensor calibration control unit 32 acquires the light receiving sensor output value from the light receiving sensor 54. At this time, the detection area AD is located at the detection position p5 in FIG.

In step SP11, the fixing release sensor calibration control unit 32 determines whether or not the light receiving sensor output value is equal to or greater than the white determination minimum threshold value THwl at the time point t5 in FIG. If a positive result is obtained here, this means that the current detection region AD is not located at least completely inside the black region AB, although it may partially contain the black region AB. A part thereof indicates that it is located inside the white region AW, and at this time, the fixing release sensor calibration control unit 32 moves to step SP13. On the other hand, if a negative result is obtained in step SP10, this means that the current detection region AD is completely located inside the black region AB, and at this time, the fixing release sensor calibration control unit 32 is in step SP17. Move to.

In this way, when the light receiving sensor output detection operation is performed three times and the light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl in all of them, the second light receiving sensor output detection operation is surely performed in all of the detection area AD. It is confirmed that the sensor was located in the white region AW. Therefore, in step SP12, the fixing release sensor calibration control unit 32 determines the LED current value and the white level tentatively determined at the time of the second light receiving sensor output detection operation at the time point t5 in FIG. 10, and determines the LED current value. The LED current value is increased to the tentatively determined LED current value, and the process proceeds to step SP13.

In step SP13, the fixing release sensor calibration control unit 32 continues to periodically acquire the light receiving sensor output value from the light receiving sensor 54, and at the time point t6 in FIG. 10, the position of the detection region AD changes from the white region AW to the black region AB. Detecting that the change has occurred, the process proceeds to step SP14. At this time, the detection area AD is located at the detection position p6 in FIG. 7. Specifically, in the fixing release sensor calibration control unit 32, when the light receiving sensor output value drops from 3.1 [V] or more to 2.0 [V] or more, the position of the detection area AD is from the white area AW. It is judged that the area has changed to the black area AB. When the detection area AD is actually located in the black area AB, the light receiving sensor output value is about 0.5 [V]. In step SP14, the fixing release sensor calibration control unit 32 waits for the measurement standby time Tms at the time point t7 in FIG. It is separated and surely located inside the black region AB, and the process proceeds to step SP15. At this time, the detection area AD is located at the detection position p7 in FIG.

In step SP15, the fixing release sensor calibration control unit 32 determines the black level at the time point t8 in FIG. 10, and proceeds to step SP16. This black level is the current light receiving sensor output value. At this time, the detection area AD is located at the detection position p8 in FIG.

In step SP16, the fixing release sensor calibration control unit 32 determines by calculating the black-and-white threshold value, moves to step SP21, and ends the calibration processing procedure RT1. Specifically, the fixing release sensor calibration control unit 32 calculates an average value between the white level and the black level, that is, a value of ((white level + black level) / 2), and sets it as a black and white threshold value.

[When the light receiving sensor output value is less than the white judgment minimum threshold value even once in 1-5-2.3 times of the light receiving sensor output detection operation]
Next, with reference to FIG. 4 and FIG. This will be described with reference to the flowchart of FIG. 5, the detection position shown in FIG. 8, and the timing chart of the light receiving sensor output value shown in FIG.

If a negative result is obtained in step SP3, the detection area AD is completely located inside the black area AB in the first light receiving sensor output detection operation. Therefore, at this time, the fixing release sensor calibration control unit 32 moves to step SP17. Move on to (Fig. 5). Similarly, if a negative result is obtained in step SP6, the detection area AD is completely located inside the black area AB in the second light receiving sensor output detection operation, so that the fixing release sensor calibration control unit 32 is at this time. , Step SP17 (FIG. 5). Similarly, if a negative result is obtained in step SP11 (FIG. 5), the detection area AD is completely located inside the black area AB in the third light receiving sensor output detection operation. The operation control unit 32 moves to step SP17.

Hereinafter, a case where a positive result is obtained in steps SP3 and SP6 but a negative result is obtained in step SP11 will be described. In step SP1, the detection area AD is assumed to be located at the detection start position ps2 in FIG. By performing the processes from step SP1 to step SP9, the fixing release sensor calibration control unit 32 reaches the time point t11 to the time point t14 shown in FIG. Here, in step SP2, the detection area AD is located at the detection position p11 in FIG. 8, the detection position moves to the detection positions p12, p13, and p14, and the third light receiving sensor output detection operation in step SP10 is performed. Previously, when the detection region AD was located at the detection position p15 and the detection region AD was completely located inside the black region AB, the fixation release sensor calibration control unit 32 in step SP11 at time point t15 in FIG. It is determined that the light receiving sensor output value is less than the white judgment minimum threshold value THwl, and the process proceeds to step SP17.

In step SP17, the fixing release sensor calibration control unit 32 continues to periodically acquire the light receiving sensor output value from the light receiving sensor 54, and at the time point t11 in FIG. 11, the position of the detection region AD changes from the black region AB to the white region AW. The change is detected, and the process proceeds to step SP18. At this time, the detection area AD is located at the detection position p16 in FIG. Specifically, the fixing release sensor calibration control unit 32 determines that the position of the detection region AD has changed from the black region AB to the white region AW when the light receiving sensor output value increases by 1.0 [V] or more. In step SP18, the fixing release sensor calibration control unit 32 waits for the measurement standby time Tms at the time point t17 in FIG. It is surely located inside the white region AW, and the process proceeds to step SP19. At this time, the detection area AD is located at the detection position p17 in FIG.

In step SP19, the fixing release sensor calibration control unit 32 gradually increases the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws at the time point t18 in FIG. 11, and proceeds to step SP20. In step SP20, the fixing release sensor calibration control unit 32 determines the LED current value and the white level at the time point t18 in FIG. 11, and proceeds to step SP13. This white level is the current output value of the light receiving sensor. At this time, the detection region AD is located at the detection position p18 in FIG.

After that, the fixing release sensor calibration control unit 32 performs the above-described processing, and at the time point t19 in FIG. 11 (detection position p19 in FIG. 8), the position of the detection region AD has changed from the white region AW to the black region AB. After detecting and waiting for the measurement waiting time Tms at the time point t20 in FIG. 11 (detection position p20 in FIG. 8), the black level is determined at the time point t21 (detection position p21 in FIG. 8) in FIG. Is calculated, the process proceeds to step SP21, and the calibration processing procedure RT1 is completed.

[1-6. Calibration process of comparative example]
Next, regarding the specific processing procedure of the calibration process by the image forming apparatus 201 of the comparative example, the flowchart of FIG. 6 in which the steps corresponding to those in FIGS. 4 and 5 are designated by the same reference numerals, and the detection positions shown in FIG. , The timing chart of the light receiving sensor output value shown in FIG. 12 will be described. The fixing release sensor calibration control unit 232 starts the calibration processing procedure RT201 by reading the calibration processing program from the storage unit and executing it, and proceeds to step SP1. At this time, it is assumed that the detection area AD is located at the detection start position ps2, which is the same detection position as in FIG. 7, as shown in FIG. In step SP1, the fixing release sensor calibration control unit 232 starts the rotation of the reflector 56 and moves to step SP17.

In step SP17, the fixing release sensor calibration control unit 232 continues to periodically acquire the light receiving sensor output value from the light receiving sensor 54, and at the time point t31 in FIG. 12, the position of the detection region AD changes from the black region AB to the white region AW. The change is detected, and the process proceeds to step SP18. At this time, the detection area AD is located at the detection position p31 in FIG. Specifically, the fixing release sensor calibration control unit 232 determines that the position of the detection region AD has changed from the black region AB to the white region AW when the light receiving sensor output value increases by 1.0 [V] or more. In step SP18, the fixing release sensor calibration control unit 232 waits for the measurement standby time Tms at the time point t32 in FIG. , Step SP19. At this time, the detection area AD is located at the detection position p32 in FIG.

In step SP19, the fixing release sensor calibration control unit 232 gradually increases the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws at the time point t33 in FIG. 12, and proceeds to step SP20. In step SP20, the fixing release sensor calibration control unit 232 determines the LED current value and the white level at the time point t33 in FIG. 12, and proceeds to step SP12. This white level is the current output value of the light receiving sensor. At this time, the detection area AD is located at the detection position p33 in FIG.

In step SP12, the fixing release sensor calibration control unit 232 continues to periodically acquire the light receiving sensor output value from the light receiving sensor 54, and at the time point t34 in FIG. 12, the position of the detection region AD changes from the white region AW to the black region AB. Detecting that the change has occurred, the process proceeds to step SP14. At this time, the detection area AD is located at the detection position p34 in FIG. Specifically, in the fixing release sensor calibration control unit 232, when the light receiving sensor output value drops from 3.1 [V] or more to 2.0 [V] or more, the position of the detection area AD is from the white area AW. It is judged that the area has changed to the black area AB. In step SP14, the fixation release sensor calibration control unit 232 waits for the measurement standby time Tms at the time point t35 in FIG. 12, so that the detection region AD is reliably located inside the white region AW away from the black-and-white boundary BDwb. Then, the process proceeds to step SP15. At this time, the detection area AD is located at the detection position p35 in FIG.

In step SP15, the fixation release sensor calibration control unit 232 determines the black level at time point t36 in FIG. 12 and proceeds to step SP16. This black level is the current light receiving sensor output value. At this time, the detection area AD is located at the detection position p36 in FIG.

In step SP16, the fixing release sensor calibration control unit 232 determines by calculating the black-and-white threshold value, moves to step SP21, and ends the calibration processing procedure RT201. Specifically, the fixing release sensor calibration control unit 232 calculates the average value of the white level and the black level, that is, the value of ((white level + black level) / 2), and sets it as the black and white threshold value.

[1-7. Effect, etc.]
Here, in the calibration processing procedure RT201 in the image forming apparatus 201 of the comparative example, when the LED current value and the white level are first determined, the fixing release sensor calibration control unit 232 receives the light receiving sensor output value as the light receiving sensor. By continuing to acquire from 54 periodically, detecting that the position of the detection area AD has changed from the black area AB to the white area AW, and waiting for the measurement waiting time Tms, the detection area AD is positioned at the black-white boundary BDbw. The LED current value and the white level are determined after making sure that the white region AW is located inside the white region AW.

Therefore, in the fixed release sensor calibration control unit 232, if the detection start position when the calibration is started is the same detection start position ps1 as in FIG. 7, the detection area AD first passes the white area AW. By entering the black region AB, further entering the white region AW from the black region AB, and waiting for the measurement standby time Tms, the detection region AD is prevented from being located at the black-white boundary BDbw, and then the LED current value and the white level are obtained. And decide. Therefore, in the case of the image forming apparatus 201 of the comparative example, it takes time to determine the LED current value and the white level, and as a result, the calibration takes time.

Further, in the case of the image forming apparatus 201 of the comparative example, when the calibration is started, if the detection start position ps2 is a position where the position of the detection area AD in FIG. 9 exceeds the black-white boundary BDbw, the LED current value. It is necessary to rotate the reflector 56 at a maximum of about one rotation before determining the white level and the white level, which requires more time for calibration.

On the other hand, the image forming apparatus 1 according to the present embodiment performs the light receiving sensor output detection operation three times with a slight rotation angle, and in the second light receiving sensor output detection operation, the LED current value and white The level is tentatively fixed. After that, in the image forming apparatus 1, when all the light receiving sensor output values for three times are equal to or higher than the white judgment minimum threshold value THwl, that is, the detection area AD enters the black area AB in all three light receiving sensor output detection operations. If not, the tentatively confirmed LED current value and white level value in the second light receiving sensor output detection operation are judged to be correct and confirmed.

Therefore, the image forming apparatus 1 has the LED current value and the LED current value in the second light receiving sensor output detection operation when all the light receiving sensor output values are equal to or higher than the white judgment minimum threshold THwl in the three light receiving sensor output detection operations. When the tentative determination of the white level is correct, the LED current value and the white level can be determined before detecting the change point from the black area AB to the white area AW of the detection area AD. As a result, the image forming apparatus 1 reduces the amount of rotation of the reflector 56 to be rotated from the start of calibration to the determination of the LED current value and the white level, as compared with the image forming apparatus 201 of the comparative example. And the time required for calibration can be shortened.

Further, the image forming apparatus 1 determines whether or not the light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl in three light receiving sensor output detection operations. Therefore, the image forming apparatus 1 eliminates the possibility that the detection area AD is located at the boundary BD in the second light receiving sensor output detection operation, and reliably detects the second light receiving sensor output detection operation in the white area AD. It can be in a state of being located inside the AW. As a result, the image forming apparatus 1 determines the LED current value and the white level value tentatively determined in the second light receiving sensor output detection operation in a state where the detection area AD is reliably located inside the white area AW. Can be.

Further, when the light receiving sensor output value is less than the white judgment minimum threshold THwl even once in the light receiving sensor output detection operation for three times, the image forming apparatus 1 has the detection region AD as in the image forming apparatus 201 of the comparative example. After detecting the change point from the black region AB to the white region AW, the LED current value and the white level are determined. Therefore, if the light receiving sensor output value is less than the white judgment minimum threshold THwl in the third light receiving sensor output detection operation, the image forming apparatus 1 is an image forming device of a comparative example as shown in FIGS. 8 and 9. In 201, the light receiving sensor output detection operation for three times is performed before detecting the change point of the detection region AD from the black region AB to the white region AW.

As described above, even if the light receiving sensor output value is less than the white judgment minimum threshold THwl in any of the three light receiving sensor output detection operations, the image forming apparatus 1 is subsequently subjected to the same as the image forming device 201 of the comparative example. In order to detect the change point from the black region AB to the white region AW of the detection region AD, the LED current value and the white level are determined at the same timing as the image forming apparatus 201 of the comparative example.

Therefore, as shown in FIG. 8, in the image forming apparatus 1, the light receiving sensor output value is the white judgment minimum threshold THwl in the third light receiving sensor output detection operation performed at the latest timing in the light receiving sensor output detection operation for three times. Even if it is less than, the timing is the same as that of the image forming apparatus 201 of the comparative example because the change point from the black region AB to the white region AW of the detection region AD is subsequently detected as in the image forming apparatus 201 of the comparative example. Will determine the LED current value and the white level. As a result, the image forming apparatus 1 can determine the LED current value and the white level at the same timing as the image forming apparatus 201 of the comparative example at the latest, and can be calibrated as compared with the image forming apparatus 201 of the comparative example. The time required will not be long.

Further, the fixing release sensor calibration control unit 32 contains the first light receiving sensor output value acquisition determination unit 60, the second light receiving sensor output value acquisition determination unit 61, and the first reflection region provisional determination unit 62, 3 shown in FIG. Each function of the second light receiving sensor output value acquisition determination unit 63, the first reflection area determination unit 64, the light reception sensor output value acquisition second reflection area determination unit 65, and the calibration unit 66 is realized.

The first light receiving sensor output value acquisition determination unit 60 acquires the first light receiving sensor output value, and determines whether or not at least a part of the detection area AD is equal to or greater than the white judgment minimum threshold THwl when the white area AW is included. judge. When the first light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl, the second light receiving sensor output value acquisition determination unit 61 moves the detection area from the position of the detection area AD where the first light receiving sensor output value is acquired. The second light receiving sensor output value is acquired on the direction ra1 side, and it is determined whether or not the white judgment minimum threshold is THwl or more.

When the output value of the second light receiving sensor is the white judgment minimum threshold value THwl, the first light receiving sensor temporarily confirms that the detection area AD is located inside the white area AW, and the second light receiving sensor The output value is stored in the memory unit 38. The third light receiving sensor output value acquisition determination unit 63 acquires the third light receiving sensor output value on the detection area moving direction ra1 side from the position of the detection area AD that acquired the second light receiving sensor output value, and determines the white minimum. It is determined whether or not the threshold value is THwl or more.

In the first reflection region determination unit 64, when the third light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl, the detection area AD is located inside the white region AW when the second light receiving sensor output value is acquired. It is confirmed that it was done. When the light receiving sensor output value acquisition second reflection area determination unit 65 is equal to or higher than the white judgment minimum threshold value THwl, the second reflection area determination unit 65 detects the third light receiving sensor output value from the position of the detection area AD where the third light receiving sensor output value is acquired. On the region moving direction ra1 side, it is determined whether or not the light receiving sensor output value is 0.5 [V] as the second reflection region value when the detection region AD is included in the black region AB. The calibration unit 66 calibrates the light receiving sensor 54 based on at least the second light receiving sensor output value.

According to the above configuration, the image forming apparatus 1 has a white region AW as a first reflection region and a black region as a second reflection region in which the light reflectances are different from each other along the reflector rotation direction r1 as the rotation direction. A reflector 56 on which AB is formed, a light emitting unit 52 that emits light when a predetermined current is passed and irradiates the detection region AD at a predetermined position of the reflector 56 with emitted light, and a detection region where the emitted light is the reflecting plate 56. A light receiving sensor 54 that receives the reflected light reflected by AD and outputs a light receiving sensor output value, and a fixing release sensor calibration control unit 32 as a control unit that detects the rotation position of the reflecting plate 56 based on a change in the light receiving sensor output value. In the calibration method of the rotation position detection mechanism 50 having The first light receiving sensor output value acquisition judgment step for determining whether or not the minimum threshold is THwl or more, and the first light receiving sensor output value is acquired when the first light receiving sensor output value is white judgment minimum threshold THwl or more. The second light receiving sensor output value is acquired on the detection area moving direction ra1 side, which is the direction opposite to the reflecting plate rotation direction r1 from the position of the detected detection area AD, and it is determined whether or not it is equal to or higher than the white judgment minimum threshold THwl. When the second light receiving sensor output value acquisition determination step and the second light receiving sensor output value are the white judgment minimum threshold THwl, it is tentatively determined that the detection area AD is located inside the white area AW, and the second time. The first reflection region temporary determination step for storing the light receiving sensor output value and the third light receiving sensor output value are acquired on the detection area moving direction ra1 side from the position of the detection region AD where the second light receiving sensor output value is acquired. , The third light receiving sensor output value acquisition judgment step for judging whether or not the white judgment minimum threshold is THwl or more, and the second light receiving sensor output when the third light receiving sensor output value is white judgment minimum threshold THwl or more. Calibration to calibrate the light receiving sensor 54 based on the first reflection area determination step for determining that the detection area AD was located inside the white area AW when the value is acquired and at least the second light receiving sensor output value. It has a sensor step.

As a result, the image forming apparatus 1 detects the change point of the detection region AD from the black region AB to the white region AW, and then determines that the detection region AD is located inside the white region AW. The light receiving sensor output value in the white region AW used for calibration can be quickly determined.

[2. Second Embodiment]
[2-1. Configuration of image forming apparatus]
As shown in FIGS. 1 and 2, the image forming apparatus 101 according to the second embodiment is fixed instead of the fixing release sensor calibration control unit 32 as compared with the image forming apparatus 1 according to the first embodiment. Although it differs in that it has a release sensor calibration control unit 132, the other points are similarly configured. The fixing release sensor calibration control unit 32 performed the light receiving sensor output detection operation three times in the calibration processing procedure RT1. On the other hand, the fixing release sensor calibration control unit 132 performs the light receiving sensor output detection operation twice in the calibration processing procedure RT101.

[2-2. Calibration process]
Regarding the specific processing procedure of the calibration process by the image forming apparatus 101, the flowcharts of FIGS. 14 and 15 in which the steps corresponding to FIGS. 4 and 5 are designated by the same reference numerals, and the timing of the light receiving sensor output value shown in FIG. This will be described using a chart.

In step SP31, the fixing release sensor calibration control unit 132 starts the rotation of the reflector 56 and moves to step SP32. In step SP32, the fixing release sensor calibration control unit 132 performs the first light receiving sensor output detection operation at the time point t41 in FIG. 16, and proceeds to step SP33. At this time, it is assumed that the detection region AD is located at, for example, the black-and-white boundary BDbw. Therefore, in step SP32, it is assumed that the fixing release sensor calibration control unit 132 has acquired 1.6 [V] as the light receiving sensor output value, which is 0.5 [V] lower than 2.1 [V].

In step SP33, the fixing release sensor calibration control unit 132 determines whether or not the light receiving sensor output value is equal to or greater than the white determination minimum threshold value THwl at the time point t42 in FIG. If a positive result is obtained here, this means that the current detection region AD is not located at least completely inside the black region AB, although it may partially contain the black region AB. A part thereof indicates that it is located inside the white region AW, and at this time, the fixing release sensor calibration control unit 132 moves to step SP34. On the other hand, if a negative result is obtained in step SP33, this means that the current detection region AD is completely located inside the black region AB, and at this time, the fixing release sensor calibration control unit 132 is in step SP18. Move on to (Fig. 5).

In step SP34, the fixing release sensor calibration control unit 132 stores the light receiving sensor output value as the first light receiving sensor output value in the memory unit 38, and proceeds to step SP35.

In step SP35, the fixing release sensor calibration control unit 132 gradually increases the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws at the time point t42 in FIG. 16, and proceeds to step SP36. For example, if the light receiving sensor output value increases by 0.5 [V] according to the amount of current increase once, and if the current light receiving sensor output value is 1.6 [V], the light receiving sensor output value is stepwise only three times. By increasing the current, the light receiving sensor output value becomes 3.1 [V].

In step SP36, the fixing release sensor calibration control unit 132 stores the LED current value and the white level as the first LED current value and the white level in the memory unit 38 at the time point t42 in FIG. 16, and proceeds to step SP37.

In step SP37, the fixing release sensor calibration control unit 132 waits for the measurement standby time Tms at the time point t43 in FIG. The state is set to be located inside the white region AW, and the process proceeds to step SP38.

In step SP38, the fixing release sensor calibration control unit 132 lowers the once increased LED current value to the value at the start of calibration at the time point t44 in FIG. 16, and proceeds to step SP39. In step SP39, the fixing release sensor calibration control unit 132 performs the second light receiving sensor output detection operation at the time point t44 in FIG. 16, and proceeds to step SP40. At this time, the detection region AD is located in the white region AW. Therefore, in step SP39, the fixing release sensor calibration control unit 132 acquires 2.1 [V] as the light receiving sensor output value.

In step SP40, the fixing release sensor calibration control unit 132 determines whether or not the light receiving sensor output value is equal to or greater than the white determination minimum threshold value THwl at the time point t45 in FIG. If an affirmative result is obtained here, this means that the current detection region AD is located inside the white region AW, and at this time, the fixing release sensor calibration control unit 132 performs step SP41 (FIG. 15). ). On the other hand, if a negative result is obtained in step SP40, this means that the current detection region AD is completely located inside the black region AB, and at this time, the fixing release sensor calibration control unit 132 is in step SP17. Move on to (Fig. 15).

In step SP41, the fixing release sensor calibration control unit 132 stores the light receiving sensor output value as the second light receiving sensor output value in the memory unit 38, and moves to step SP42.

In step SP42, the fixing release sensor calibration control unit 132 gradually increases the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws at the time point t45 in FIG. 16, and proceeds to step SP43. For example, if the light receiving sensor output value increases by 0.5 [V] according to the amount of current increase once, and if the current light receiving sensor output value is 2.1 [V], the light receiving sensor output value is gradually increased only twice. By increasing the current, the light receiving sensor output value becomes 3.1 [V].

In step SP43, the fixing release sensor calibration control unit 132 stores the LED current value and the white level as the second LED current value and the white level in the memory unit 38 at the time point t45 in FIG. 16, and proceeds to step SP44.

In step SP44, the fixing release sensor calibration control unit 132 compares the first LED current value and the second LED current value, adopts the LED current value and the white level having the larger values, and proceeds to step SP13. That is, when the first LED current value is larger than the second LED current value, the fixing release sensor calibration control unit 132 adopts the first LED current value and the white level stored in step SP36 as official values. .. On the other hand, when the second LED current value is larger than the first LED current value, the fixing release sensor calibration control unit 132 adopts the second LED current value and the white level stored in step SP43 as official values. do.

After that, the fixing release sensor calibration control unit 132 performs the same processing as the fixing release sensor calibration control unit 32 according to the first embodiment, and the position of the detection region AD is from the white region AW at the time point t46 in FIG. After detecting the change to the black region AB and waiting for the measurement standby time Tms at the time point t47 in FIG. 16, the black level was determined at the time point t48 in FIG. 16, and then the LED current value and the white level were adopted. The black-and-white threshold is calculated using the white level in the light receiving sensor output detection operation of the other side, and the process proceeds to step SP21 to end the calibration processing procedure RT101.

In this way, the image forming apparatus 101 performs the light receiving sensor output detection operation twice while leaving a slight rotation angle, and stores the first light receiving sensor output value in the first light receiving sensor output detection operation. After gradually increasing the LED current value until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws, the first LED current value and white level are memorized, and then in the second light receiving sensor output detection operation, the second time. The light receiving sensor output value is stored, the LED current value is gradually increased until the light receiving sensor output value becomes equal to or higher than the white saturation threshold THws, and then the second LED current value and the white level are stored. Subsequently, the image forming apparatus 101 compares the output value of the first light receiving sensor with the output value of the second light receiving sensor, and adopts the LED current value and the white level in the light receiving sensor output detection operation having the larger value.

Therefore, the image forming apparatus 101 can reduce the light receiving sensor output detecting operation to two times as compared with the image forming apparatus 1 which performs the light receiving sensor output detecting operation three times. As a result, the image forming apparatus 101 needs to increase the LED current value until the light receiving sensor output value becomes the white saturation threshold THws or more in each light receiving sensor output detection operation as compared with the image forming apparatus 1, and the control is somewhat uncontrolled. Although it becomes complicated, the time required for calibration can be further shortened.

Further, the fixing release sensor calibration control unit 132 contains the first light receiving sensor output value acquisition determination unit 70, the first light receiving sensor output value storage unit 71, and the second light receiving sensor output value acquisition determination unit 72, as shown in FIG. The functions of the second light receiving sensor output value storage unit 73, the first reflection area determination unit 74, the light receiving sensor output value acquisition second reflection area determination unit 75, and the calibration unit 76 are realized.

The first light receiving sensor output value acquisition determination unit 70 acquires the first light receiving sensor output value, and determines whether or not at least a part of the detection area AD is equal to or greater than the white judgment minimum threshold THwl when the white area AW is included. judge. The first light receiving sensor output value storage unit 71 stores the first light receiving sensor output value when the first light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl.

The second light receiving sensor output value acquisition determination unit 61 acquires the second light receiving sensor output value on the detection area moving direction ra1 side from the position of the detection area AD where the first light receiving sensor output value is acquired, and the white judgment is the lowest. It is determined whether or not the threshold value is THwl or more. The second light receiving sensor output value storage unit 73 stores the second light receiving sensor output value when the second light receiving sensor output value is equal to or higher than the white determination minimum threshold value THwl.

The first reflection region determination unit 74 compares the output value of the first light receiving sensor with the output value of the second light receiving sensor, and when the light receiving sensor output value having the larger value is acquired, the detection area AD is a white region. It is confirmed that it was located inside the AW. In the light receiving sensor output value acquisition second reflection area determination unit 75, the light receiving sensor output value is black in the detection area AD on the detection area moving direction ra1 side from the position of the detection area AD in which the second light receiving sensor output value is acquired. It is determined whether or not it is 0.5 [V] as the second reflection region value when it is included in the region AB. The calibration unit 76 calibrates the light receiving sensor 54 based on at least the light receiving sensor output value determined that the detection region AD is located inside the white region AW.

In the above configuration, the image forming apparatus 101 emits light by flowing a predetermined current through the reflecting plate 56 in which the white region AW and the black region AB having different light reflectances are formed along the reflecting plate rotation direction r1. A light emitting unit 52 that irradiates the detection region AD at a predetermined position of the reflection plate 56 with emitted light, and a light receiving sensor 54 that receives the reflected light reflected by the emitted light in the detection region AD of the reflecting plate 56 and outputs a light receiving sensor output value. In the calibration method of the rotation position detection mechanism 50 having the fixing release sensor calibration control unit 132 as a control unit that detects the rotation position of the reflector 56 based on the change in the output value of the light reception sensor, the first light reception sensor The first light reception sensor output value acquisition judgment step and the first light reception to acquire the output value and determine whether or not at least a part of the detection area AD is included in the white area AW, which is equal to or higher than the white judgment minimum threshold THwl. When the sensor output value is equal to or greater than the white judgment minimum threshold THwl, from the position of the first light receiving sensor output value storage step for storing the first light receiving sensor output value and the position of the detection area AD where the first light receiving sensor output value is acquired. Also, the second light receiving sensor output value is acquired on the detection area moving direction ra1 side, and the second light receiving sensor output value acquisition judgment step and the second light receiving sensor output are determined to determine whether or not the white judgment minimum threshold is THwl or higher. When the value is equal to or greater than the white judgment minimum threshold THwl, the second light receiving sensor output value storage step for storing the second light receiving sensor output value is compared with the first light receiving sensor output value and the second light receiving sensor output value. Then, when the light receiving sensor output value having the larger value is acquired, the first reflection region determination step for determining that the detection region AD is located inside the white region AW, and at least the detection region AD is inside the white region AW. It is provided with a calibration step for calibrating the light receiving sensor 54 based on the light receiving sensor output value determined to be located.

As a result, the image forming apparatus 101 can further shorten the time required for calibration as compared with the image forming apparatus 1.

In other respects, the image forming apparatus 101 according to the second embodiment can exhibit substantially the same effects as the image forming apparatus 1 according to the first embodiment.

[3. Other embodiments]
In the first embodiment described above, the case where the light receiving sensor output detection operation is performed three times has been described. The present invention is not limited to this, and the light receiving sensor output detection operation is performed four times or more, and the light receiving sensor output value when the light receiving sensor output value is less than the white judgment minimum threshold THwl in the light receiving sensor output detection operation is excluded. The second light receiving sensor output value when the light receiving sensor output value is equal to or higher than the white judgment minimum threshold value THwl three times in a row may be adopted. In that case, it is possible to reduce the possibility of shifting to the control for detecting that the position of the detection region AD has changed from the black region AB to the white region AW as in the image forming apparatus 201 of the comparative example.

Further, in the first embodiment described above, the case where the measurement standby time Tms is set to 100 [ms] has been described. The present invention is not limited to this, and the measurement waiting time Tms may be various values larger or smaller than 100 [ms]. In this case, when the measurement waiting time Tms is made smaller than 100 [ms], the rotation angle of the reflector 56 rotating during the measurement waiting time Tms becomes smaller than 13 [°], and the measurement waiting time Tms is set to 100 [ms]. If it is made larger than, the rotation angle of the reflector 56 that rotates during the measurement standby time Tms becomes larger than 13 [°]. Here, if the rotation angle of the reflector 56 that rotates during the measurement standby time Tms is too large, it is detected during the measurement standby time Tms between the previous light receiving sensor output detection operation and the current light receiving sensor output detection operation. There is a possibility that the region AD jumps over the black region AB and the calibration cannot be performed accurately. On the other hand, if the rotation angle of the reflector 56 that rotates during the measurement standby time Tms is too small, the detection area AD may be located in the black area AB or in the boundary BD in all the light receiving sensor output detection operations. .. Therefore, the measurement waiting time Tms is an angle smaller than the black region occupying angle range while considering the size of the detection region AD, and is the minimum such that the detection region AD can avoid the inside of the black region AB and the boundary BD. It is preferably a limited time. The same applies to the second embodiment.

Further, in the first embodiment described above, the white region AW is formed over a wide rotation angle range of 290 [°] among the rotation angles of 360 [°] on the reflector 56. The case where the black region AB is formed over a rotation angle range of 70 [°], which is a narrow rotation angle range, has been described. The present invention is not limited to this, and the white and black color arrangements are reversed, and the black region covers a wide rotation angle range of 290 [°] among the 360 [°] rotation angles of the reflector 56. AB may be formed, and a white region AW may be formed over a rotation angle range of 70 [°], which is a narrow rotation angle range. The same applies to the second embodiment.

Further, in the first embodiment described above, the case where the white region AW is white and the black region AB is black has been described. The present invention is not limited to this, and the white region AW and the black region AB may be various other colors. In that case, it is preferable to combine a color having a high light reflectance and a color having a low light reflectance. The same applies to the second embodiment.

Further, in the first embodiment described above, the case where the black region occupying angle range is 70 [°] has been described. The present invention is not limited to this, and the black region occupancy angle range may be various values larger or smaller than 70 [°]. The same applies to the second embodiment.

Further, in the first embodiment described above, the present invention is applied to the rotation position detecting mechanism 50 that detects the release state or the nip state of the pressure roller 18 in the fuser 11 based on the rotation position of the reflector 56. Stated. The present invention is not limited to this, and for example, image formation when the image forming unit 3 itself is moved in the vertical direction so that the photoconductor drum 4 of the image forming unit 3 can abut or separate from the transport belt 7. The present invention may be applied to various rotation position detection mechanisms such as a rotation position detection mechanism that detects the position of the unit 3 based on a rotation member, a rotation position detection mechanism that detects the rotation position of an impeller that conveys paper, and the like. .. The same applies to the second embodiment.

Further, in the above-described embodiment, the case where the present invention is applied to the image forming apparatus 1 or 101 has been described. The present invention is not limited to this, and the present invention may be applied to devices such as facsimile machines, MFPs (MultiFunction Printers), and copiers having a rotation position detection mechanism.

Furthermore, the present invention is not limited to the above-described embodiments and other embodiments. That is, the scope of the present invention extends to an embodiment in which each of the above-described embodiments and a part or all of the above-mentioned other embodiments are arbitrarily combined, and an embodiment in which a part is extracted. Is.

The present invention can be used not only in a computer for printing an image on an image forming apparatus, but also in various electronic devices such as an image scanner, a facsimile apparatus, and a copying machine that perform various processing related to an image.

1, 101 ... Image forming device, 2 ... Device housing, 3 ... Image forming unit, 4 ... Photoreceptor drum, 5 ... Toner cartridge, 6 ... Transfer unit, 7 ... Conveying belt, 8 ... ... Transfer roller, 9 ... Tray, 10 ... Hopping roller, 11 ... Fixer, 12 ... Stacker, 16 ... Heating roller, 18 ... Pressurized roller, 20 ... System control unit, 22 ... Connection I / F unit, 24 ... image data storage unit, 26 ... print control unit, 28 ... medium paper feed control unit, 30 ... medium transport control unit, 32, 132 ... fixing release sensor calibration control unit, 34 ... Fixing control unit, 36 ... Operation display unit, 38 ... Memory unit, 40 ... Print control data storage unit, 42 ... Fixing temperature width setting storage unit, 50 ... Rotation position detection mechanism, 52 ... Light emitting unit, 54 ... Light receiving sensor, 56 ... Reflecting plate, 60 ... 1st light receiving sensor output value acquisition judgment unit, 61 ... 2nd light receiving sensor output value acquisition judgment unit, 62 ... First reflection region provisionally confirmed Unit, 63 ... 3rd light receiving sensor output value acquisition determination unit, 64 ... 1st reflection area determination unit, 65 ... light receiving sensor output value acquisition second reflection area determination unit, 66 ... calibration unit, 70 ... 1st light receiving sensor output value acquisition judgment unit, 71 ... 1st light receiving sensor output value storage unit, 72 ... 2nd light receiving sensor output value acquisition judgment unit, 73 ... 2nd light receiving sensor output value storage unit, 74 ... 1st reflection area determination unit, 75 ... light receiving sensor output value acquisition 2nd reflection area determination unit, 76 ... calibration unit, AW ... white area, AB ... black area, BD ... boundary, BDwb ... black and white Boundary, BDbw ... Black-white boundary, r1 ... Reflector rotation direction, ra1 ... Detection area movement direction, AD ... Detection area, THwl ... White judgment minimum threshold, THws ... White saturation threshold, Tms ... Measurement standby time.

Claims (8)

A reflector in which a first reflection region and a second reflection region having different light reflectances along the rotation direction are formed.
A light emitting unit that emits light when a predetermined current is passed and irradiates the detection region at a predetermined position of the reflector with emitted light.
A light receiving sensor that receives the reflected light reflected by the emitted light in the detection region of the reflector and outputs a light receiving sensor output value.
In a calibration method in a rotation position detection mechanism having a control unit that detects the rotation position of the reflector based on a change in the output value of the light receiving sensor.
The first light receiving sensor output value for acquiring the first light receiving sensor output value and determining whether or not at least a part of the detection area is equal to or more than the first reflection area determination threshold value when the first reflection area is included in the first reflection area. Acquisition judgment step and
When the first light receiving sensor output value is equal to or higher than the first reflection area determination threshold value, the second light receiving is received on the detection area moving direction side from the position of the detection area where the first light receiving sensor output value is acquired. The second light receiving sensor output value acquisition determination step of acquiring the sensor output value and determining whether or not it is equal to or greater than the first reflection region determination threshold value, and
When the second light receiving sensor output value is equal to or higher than the first reflection area determination threshold value, it is tentatively determined that the detection area is located inside the first reflection area, and the second light receiving sensor output value is set. The first reflection region tentative determination step to be memorized and
Whether or not the light receiving sensor output value for the third time is acquired on the detection region moving direction side from the position of the detection region from which the second light receiving sensor output value is acquired and is equal to or higher than the first reflection region determination threshold value. The third light receiving sensor output value acquisition judgment step and
When the third light receiving sensor output value is equal to or higher than the first reflection area determination threshold value, it is said that the detection area is located inside the first reflection area when the second light receiving sensor output value is acquired. The first reflection region determination step to be determined and
A calibration method including a calibration step of calibrating the light receiving sensor based on at least the output value of the light receiving sensor for the second time. If any one of the first light receiving sensor output value, the second light receiving sensor output value, or the third light receiving sensor output value is less than the first reflection region determination threshold value, then Whether or not the light receiving sensor output value is a value when the detection region moves from the second reflection region to the first reflection region on the side of the detection region moving direction with respect to the position of the detection region. The light receiving sensor output value acquisition first reflection region determination step and
The light receiving sensor output value is acquired on the detection area moving direction side with respect to the position of the detection area when it is determined that the detection area is a value when the detection area is moved from the second reflection area to the first reflection area. Further, it has a first reflection region determination step for determining that the detection region is located inside the first reflection region.
The calibration method according to claim 1, wherein the calibration step calibrates the light receiving sensor based on the light receiving sensor output value acquired in the first reflection region determination step. In the second light receiving sensor output value acquisition determination step, when the second light receiving sensor output value is equal to or greater than the first reflection region determination threshold value, the current value of the light emitting unit is set to a predetermined value by the light receiving sensor output value. The calibration method according to claim 1 or 2, wherein the calibration method is increased until the temperature is reached. When the third light receiving sensor output value is equal to or higher than the first reflection region determination threshold value, the light receiving sensor is located on the detection region moving direction side with respect to the position of the detection region where the third light receiving sensor output value is acquired. The light receiving sensor output value acquisition second reflection region determination step for determining whether or not the output value is the second reflection region value when the detection region is included in the second reflection region is further included.
When the light receiving sensor output value is the second reflection region value, the calibration step is the current of the light emitting unit when the second light receiving sensor output value and the second light receiving sensor output value are acquired. The method according to any one of claims 1 to 3, wherein the calibration of the light receiving sensor is performed based on the value and the light receiving sensor output value when the light receiving sensor output value is the second reflection region value. Calibration method. In the calibration step, the average value of the second light receiving sensor output value and the light receiving sensor output value when the light receiving sensor output value is the second reflection region value is calculated, and the average value is calculated. The calibration method according to claim 4, wherein the detection region is set as a threshold value of the light receiving sensor output value when determining whether the detection region is located in either the first reflection region or the second reflection region. A reflector in which a first reflection region and a second reflection region having different light reflectances along the rotation direction are formed.
A light emitting unit that emits light when a predetermined current is passed and irradiates the detection region at a predetermined position of the reflector with emitted light.
A light receiving sensor that receives the reflected light reflected by the emitted light in the detection region of the reflector and outputs a light receiving sensor output value.
In a calibration method in a rotation position detection mechanism having a control unit that detects the rotation position of the reflector based on a change in the output value of the light receiving sensor.
The first light receiving sensor output value for acquiring the first light receiving sensor output value and determining whether or not at least a part of the detection area is equal to or more than the first reflection area determination threshold value when the first reflection area is included in the first reflection area. Acquisition judgment step and
When the first light receiving sensor output value is equal to or higher than the first reflection region determination threshold value, the first light receiving sensor output value storage step for storing the first light receiving sensor output value and the first light receiving sensor output value storage step.
Whether or not the second light receiving sensor output value is acquired on the detection region moving direction side of the position of the detection region from which the first light receiving sensor output value is acquired and is equal to or greater than the first reflection region determination threshold value. Judgment The second light receiving sensor output value acquisition judgment step and
When the second light receiving sensor output value is equal to or higher than the first reflection region determination threshold value, the second light receiving sensor output value storage step for storing the second light receiving sensor output value and the second light receiving sensor output value storage step.
When the first light receiving sensor output value is compared with the second light receiving sensor output value and the light receiving sensor output value having the larger value is acquired, the detection region is located inside the first reflection region. The first reflection region determination step to determine that it was done, and
A calibration method including a calibration step of calibrating the light receiving sensor based on at least the output value of the light receiving sensor determined that the detection region was located inside the first reflection region. When either the first light receiving sensor output value or the second light receiving sensor output value is less than the first reflection area determination threshold value, the detection area moving direction is larger than the position of the detection area at that time. On the side, the light receiving sensor output value acquisition first reflection region determination step of determining whether or not the light receiving sensor output value is a value when the detection region moves from the second reflection region to the first reflection region. When,
The light receiving sensor output value is acquired on the detection area moving direction side with respect to the position of the detection area when it is determined that the detection area is a value when the detection area is moved from the second reflection area to the first reflection area. Further, it has a first reflection region determination step for determining that the detection region is located inside the first reflection region.
The calibration method according to claim 6, wherein the calibration step calibrates the light receiving sensor based on the light receiving sensor output value acquired in the first reflection region determination step. Any of claims 1 to 7, wherein the control unit detects a release state or a nip state between the heating roller and the pressurizing roller in the fuser of the image forming apparatus based on the detected rotation position of the reflector. The calibration method described in.

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