JP5736973B2 - Printing apparatus, optical sensor stain determination method, and optical sensor stain determination program - Google Patents

Description

  The present invention relates to a technique for detecting contamination of an optical sensor having a detection region on a carrier.

  There is a printing apparatus that includes a density sensor that detects the density of a toner image formed on an intermediate transfer drum. In this printing apparatus, the toner image adheres to the surface of the density sensor due to toner leakage from the developing device or scattering of toner when forming the toner image on the intermediate transfer drum, so that the density detection of the toner image can be performed accurately. There is a risk of disappearing. Therefore, there is a conventional laser beam printer that determines whether the density sensor is dirty (see Patent Document 1). In this conventional laser beam printer, the density sensor irradiates light on the surface of the intermediate transfer drum at the same fixed position as when the toner image is formed, receives the reflected light, and the received light amount of the reflected light is the threshold. When the value is equal to or smaller than the value, it is determined that the lens surface of the density sensor is dirty.

JP-A-11-202696

  However, a carrier such as an intermediate transfer drum may change its reflectivity due to aging, scratches, toner adhesion, and the like. In the conventional laser beam printer described above, the density sensor detects the change in reflectivity. Since the amount of received light also fluctuates, there is a problem in that it is impossible to accurately determine the contamination on the lens surface of the density sensor. Such a problem is not limited to the density sensor, and may similarly occur if the optical sensor includes at least a part of the carrier in the detection region. The same problem can occur not only in an electrophotographic system such as a laser beam printer but also in an inkjet printing apparatus.

  The present specification discloses a technique that can suppress the influence of fluctuations in the reflectance of the carrier when determining the contamination of an optical sensor.

  The printing apparatus disclosed in this specification includes an image forming unit that forms an image, a light emitting element, a light receiving element, and a light transmitting body, and emits light that has passed through the light transmitting body from the light emitting element to a detection region. An optical sensor that receives light transmitted through the light transmitting body from the detection region, a reference position that carries a colorant image that is at least partially included in the detection region and formed by the image forming unit, and the reference A carrier that can move to a position farther from the optical sensor than a position; a carrier detector that detects whether the carrier is farther from the optical sensor than the reference position; and When the carrier detection unit detects that the carrier sensor is further away from the optical sensor than a reference position, the optical sensor is provided with a light emission control value to emit light having a light amount corresponding to the light emission control value. Sen The light projecting / receiving control unit that acquires the amount of received light at the light source, and the at least one of the light emission control value given by the light projecting / receiving control unit and the acquired light receiving amount is outside a specified range, it is determined that the optical sensor is dirty. A dirt determination unit.

  In the printing apparatus, the light projecting / receiving control unit may acquire the amount of light received by the optical sensor for the light emitted from the light emitting element and diffusely reflected by the carrier disposed at the reference position.

  In the printing apparatus, the displacement is between a first support state in which the carrier is supported at the reference position and a second support state in which the carrier is supported at a position farther from the optical sensor than the reference position. The carrier detection unit may detect that the carrier is further away from the optical sensor than the reference position when the displacement mechanism is in the second support state. .

  The printing apparatus includes a main body case that accommodates at least the image forming unit, the optical sensor, and the carrier and has an opening. The displacement mechanism includes a cover that holds the carrier. The support state may be a state where the cover is closed and the opening is closed, and the second support state may be a state where the cover is opened and the opening is opened.

  The printing apparatus includes a carrier sensor that detects whether or not the carrier is in the reference position, and the image carrier detector detects the carrier from the reference position based on a detection result of the carrier sensor. It may also be detected whether or not it is away from the optical sensor.

  In the printing apparatus, the optical sensor may be an infrared sensor in which the light emitting element emits infrared light and the light receiving element receives infrared light.

  The printing apparatus may include a notification unit that notifies a determination result by the stain determination unit.

  The present invention can be realized in various forms such as a stain determination method, a printing apparatus, a computer program for realizing the functions of these methods or apparatuses, and a recording medium on which the computer program is recorded.

  According to the present invention, it is possible to suppress the influence due to the fluctuation of the reflectance of the carrier in determining the contamination of the optical sensor.

1 is a schematic configuration diagram of a printer with a cover closed according to an embodiment. Schematic configuration diagram of printer with cover open Outline configuration diagram of registration sensor Block diagram showing the electrical configuration of the printer Flow chart showing dirt judgment processing

<One Embodiment>
An embodiment will be described with reference to FIGS. The printer 1 according to the present embodiment is an example of a printing apparatus, and is a so-called vertical direct tandem color laser printer. 1 and 2 are schematic configuration diagrams of the printer 1 according to the present embodiment. FIG. 1 shows a state in which the cover 23 is closed, and the position of the transport belt 16 at this time is an example of a reference position. FIG. 2 shows a state in which the cover 23 is open, and the position of the conveyor belt 16 at this time is an example of a position farther from the registration sensor 17 than the reference position. In the following description, the left side of each figure is the front of the printer 1.

(Entire printer configuration)
The printer 1 includes a box-shaped main body case 2, and a sheet cassette 4 on which sheets 3 are stacked is provided at the bottom of the printer 1 so that the sheet cassette 4 can be pulled forward. Note that the sheet 3 includes paper, an OHP sheet, and the like. The sheets 3 stacked on the sheet cassette 4 are sent out one by one by supply rollers 5 and 6 provided at the upper front end of the sheet cassette 4.

  In the main body case 2, four image forming units 10 corresponding to the respective colors of black, cyan, magenta, and yellow are arranged side by side in the vertical direction. Each image forming unit 10 has a flat and slender box shape as a whole. The image forming unit 10 supplies toner to a toner storage unit 11, a photoconductor 12 and a photoconductor 12 that store toner as a colorant. Development means (not shown) for visualizing the electrostatic latent image above is provided. The photoconductor 12 is provided at the front end position of the image forming unit 10 so as to be exposed on the outer surface, and the toner storage portion 11 is disposed on the rear side of the photoconductor 12. Each image forming unit 10 is an example of an image forming unit.

  An exposure device 14 is provided on the rear side of each image forming unit 10. Each exposure device 14 emits a laser beam L1 based on image data corresponding to each color and irradiates the surface of each photoconductor 12 to form an electrostatic latent image.

  A belt unit 15 is provided on the front side of the image forming unit 10. The belt unit 15 includes an endless transport belt 16 that is stretched in the vertical direction so as to face each photoconductor 12. The conveyor belt 16 is an example of a carrier. A transfer roller (not shown) is provided on the inner side of the conveyor belt 16 at a position facing each photoconductor 12 with the conveyor belt 16 in between. The sheet 3 sent from the supply rollers 5 and 6 is adsorbed on the rear side of the conveyor belt 16 and conveyed upward. Then, when the surface of the sheet 3 faces each photoconductor 12, the toner images formed on each photoconductor 12 are sequentially transferred. The toner image is an example of a colorant image.

  A registration sensor 17 is provided in the main body case 2 above the image forming unit 10. A symbol E in FIGS. 1 and 2 indicates a detection region of the registration sensor 17. The registration sensor 17 is used for detecting the position and density of a mark formed on the transport belt 16, for example. The image forming unit 10 forms an image on the sheet 3 on the conveyance belt 16 at the formation timing and density corrected according to the detection result of the registration sensor 17. The registration sensor 17 is an example of an optical sensor, and a specific configuration will be described later.

  A fixing device 19 is provided above the belt unit 15. The fixing device 19 heat-fixes the toner image transferred on the sheet 3 to the surface. The sheet 3 having passed through the fixing device 19 is discharged onto a discharge tray 20 provided on the upper surface of the main body case 2.

  An opening 22 is provided on the front surface of the main body case 2, and the opening 22 is covered with a cover 23 having a rectangular plate shape so as to be opened and closed. Hinge shafts 24 are provided at both ends of the lower end portion of the cover 23, and each hinge shaft 24 is pivotally supported by a pair of left and right bearing portions 25 provided at the lower end portion of the front surface of the main body case 2. The hinge shaft 24 is pivotable.

  The main body case 2 is provided with a cover sensor 26 that detects that the cover 23 is opened by a predetermined amount or more. Specifically, as shown in FIG. 2, the cover sensor 26 outputs the detection signal SG1 when the cover 23 is opened to such an extent that the conveyance belt 16 does not exist in the detection area E of the registration sensor 17. As the cover sensor 26, a known sensor such as an optical type, a pressure type, or a magnetic type can be used. The cover sensor 26 is an example of a carrier detection unit.

  A handle portion (not shown) is provided at the upper end of the cover 23 so as to protrude upward from the upper surface of the main body case 2. Further, the belt unit 15 described above is held on the inner surface side of the cover 23 in a detachable state. By closing the cover 23, the conveyor belt 16 can be in the first support state shown in FIG. 1, and by opening the cover 23, the conveyor belt 16 can be in the second support state shown in FIG. Therefore, the cover 23, the hinge shaft 24, and the bearing portion 25 are examples of a displacement mechanism.

(Configuration of registration sensor)
FIG. 3 is a schematic configuration diagram of the registration sensor 17. The registration sensor 17 is an infrared sensor having a light emitting element 30, a light receiving element 31, and a light transmitting body 32. The light emitting element 30 emits light in the infrared region, that is, infrared L2 toward the conveyance path of the sheet 3. The light transmitting body 32 is a film or a lens, is made of a light transmitting material such as glass or acrylic, and is disposed in front of the light emitting element 30 and the light receiving element 31. The irradiation area of the infrared ray L2 is the detection area E.

  The light receiving element 31 has, for example, a film or a filter that blocks visible light, thereby receiving infrared light without receiving visible light. Further, the light receiving element 31 receives only the diffusely reflected infrared light L3B out of the infrared light emitted from the light emitting element 30 and reflected by the conveyor belt 16 with the cover 23 closed as shown in FIG. Infrared light L3A is not received. Since the light reflectance of the sheet 3 is lower than that of the conveyance belt 16, the amount of light received by the light receiving element 31 is smaller when the sheet 3 is not present than when the sheet 3 is present in the detection region E. The registration sensor 17 outputs a detection signal SG2 indicating that the sheet 3 is present when the amount of received light is lower than a predetermined first threshold value.

(Electrical configuration of printer)
FIG. 4 is a block diagram illustrating an electrical configuration of the printer 1. The printer 1 includes a control circuit 41, an operation unit 42, and the like in addition to the image forming unit 10, the registration sensor 17, and the cover sensor 26 described above.

  The control circuit 41 (an example of a light projection / reception control unit and a dirt determination unit) includes a CPU 41A, a ROM 41B, a RAM 41C, an NVRAM 41D, and the like. The ROM 41B stores a program for executing a stain determination process, which will be described later, and the CPU 41A executes each program read from the ROM 41B and controls each unit of the printer 1.

  The operation unit 42 includes a power button for a user to input a power-off command and a power-on command for the printer 1, an operation button for inputting various settings and instructions, a liquid crystal display for displaying various information, and the like. It consists of

(Registration sensor contamination judgment process)
FIG. 5 is a flowchart showing the dirt determination process of the registration sensor 17. When the printer 1 is powered on, the CPU 41A reads the program from the ROM 41B and executes the stain determination process shown in FIG. First, the CPU 41A determines whether or not the cover 23 is opened by a predetermined amount or more based on whether or not the detection signal SG1 is received from the cover sensor 26 (S1).

  When the CPU 41A determines that the cover 23 has not been opened more than a predetermined amount (S1: NO), the conveyor belt 16 may be present in the detection area E of the registration sensor 17, so that the registration sensor 17 becomes dirty. The process returns to S1 without executing the determination. On the other hand, when the CPU 41A determines that the cover 23 is opened by a predetermined amount or more (S1: YES), the conveyance belt 16 does not exist in the detection area E of the registration sensor 17, and therefore the registration sensor 17 Perform a dirt check.

  Specifically, the CPU 41A gives a light emission control value such as a PWM value to a light emission drive circuit (not shown). Then, the light emission drive circuit causes the light emitting element 30 to emit infrared light having a light amount corresponding to the light emission control value (S2). Next, the CPU 41A acquires the amount of light received by the light receiving element 31 (S3), and compares the amount of received light with the second threshold (S4). Here, if the light transmitting body 32 is not dirty, most of the infrared rays L2 emitted from the light emitting element 30 pass through the light transmitting body 32 and the detection region E and are not received by the light receiving element 31. . For this reason, the amount of received light is less than the second threshold (S4: YES), and the process returns to S1.

  On the other hand, when an adhering substance such as toner adheres to the front surface of the light transmitting body 32 and becomes dirty, a part of the infrared ray L2 emitted from the light emitting element 30 is reflected by the adhering substance, and the light receiving element 31. The light is received at. For this reason, the amount of received light is equal to or greater than the second threshold (S4: NO), a notification operation for notifying that the registration sensor 17 is dirty is executed (S5), and the process returns to S1. As a notification operation, a message indicating that the registration sensor 17 is dirty is displayed on the liquid crystal display, output by a sounding device (not shown), or notified to an external device that is communicably connected to the printer 1. And outputting a signal. As a result, the user or the like can be notified that the registration sensor 17 is dirty.

(Effect of this embodiment)
If the conveyance belt 16 is in a position where it exists in the detection area E and the registration sensor 17 is determined to be dirty, the amount of light received by the light receiving element 31 is due to scratches on the conveyance belt 16 or the like. Since it is easily affected by fluctuations in the light reflectance, it is impossible to accurately determine whether the registration sensor 17 is dirty.

  Specifically, as an example of the case where the amount of light received by the light receiving element 31 increases, (1) the conveyance belt 16 is dirty and the light transmitting body 32 is not dirty, (2) the conveyance belt 16 is dirty. If the light transmitting body 32 is dirty, (3) the transport belt 16 may be dirty and the light transmitting body 32 may be dirty. If the conveyor belt 16 is present in the detection area E, the conveyor belt 16 is easily affected by fluctuations in the light reflectivity of the conveyor belt 16, so that the light transmission body 32 is actually not contaminated (1). As in the case of (3), there is a possibility that the light transmission body 32 may be erroneously determined to be dirty.

  On the other hand, according to the present embodiment, when the conveyor belt 16 is in a position that does not exist in the detection area E more than a position that exists in the detection area E (S1: YES), A light receiving operation is performed to determine the contamination of the registration sensor 17 (S2 to S4). Therefore, compared to the above configuration in which the presence / absence of contamination of the registration sensor 17 is determined in a state where the conveyance belt 16 is present in the detection region E, the conveyance belt 16 is less affected by fluctuations in the light reflectance of the conveyance belt 16. Therefore, it is possible to prevent the case (1) from being erroneously determined that the light transmitting body 32 is contaminated. That is, according to the present embodiment, it is possible to suppress the influence due to the change in the reflectance of the conveyor belt 16 in the stain determination of the registration sensor 17.

  Compared to regular reflection light from the conveyance belt 16, diffuse reflection light from the conveyance belt 16 is less affected by fluctuations in the amount of light received by the light receiving element 31 due to the presence or absence of the conveyance belt 16 in the detection region E. Therefore, according to the present embodiment, the light receiving element 31 is configured to receive light emitted from the light emitting element 30 and diffusely reflected by the conveyor belt 16. As a result, as compared with the configuration in which the light receiving element 31 receives the regular reflection light on the conveyance belt 16, the influence of fluctuations in the amount of light received by the light reception element 31 due to the presence or absence of the conveyance belt 16 in the detection region E is suppressed. The presence / absence judgment of the contamination sensor 17 can be accurately determined.

  Further, by detecting that the cover 23 is opened by a predetermined amount or more, it is indirectly detected that the conveyor belt 16 is not present in the detection region E. Therefore, it is possible to detect that the conveyor belt 16 no longer exists in the detection region E using the existing cover 23 and cover sensor 26 without detecting the conveyor belt 16 itself. In addition, the registration sensor 17 uses a period during which the user opens the cover 23 in order to access internal components such as the image forming unit 10 to replace consumables and to remove the jammed sheet 3. The presence or absence of dirt can be determined.

  The presence / absence of contamination of the registration sensor 17 may be determined using visible light, but is easily affected by disturbance light such as visible light when the cover 23 is opened. On the other hand, in this embodiment, since the presence or absence of contamination of the registration sensor 17 is determined using infrared rays, the influence of disturbance light when the cover 23 is opened can be suppressed.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.

  (1) In the embodiment described above, a vertical tandem color laser printer is used as an example of a printing apparatus. However, the printing apparatus may be a horizontal direct tandem system or an intermediate transfer tandem system having an intermediate transfer member. In the latter case, an intermediate transfer member, such as an intermediate transfer belt, is an example of a carrier. Further, the printing apparatus may be a system other than the tandem system such as a 4-cycle system, an electrophotographic system other than the laser system such as an LED system, and an ink jet system. Further, the printing apparatus may be a multifunction machine having other functions such as a scanning function and a facsimile function in addition to a printer having only a printing function, and may be a facsimile machine alone or a copying machine alone.

  (2) In the above embodiment, the conveyance belt 16 that indirectly conveys the colorant image via the sheet 3 is described as an example of the carrier. However, the carrier is not limited to a belt member, and may be a roller member, or may be a photosensitive member or an intermediate transfer member that directly supports a colorant image.

  (3) In the above embodiment, as an example of the optical sensor, the registration sensor 17 that detects the presence / absence, density, and the like of the toner image formed on the belt 13 is described. However, the optical sensor is not limited to a sensor that detects the presence or absence of a sheet, and may be a sensor that detects the presence or absence of a sheet 3 in the conveyance path of the sheet 3. In short, the optical sensor may be any sensor as long as the carrier is included in at least a part of the detection region and can be received at a position where light from the carrier can be received.

  (4) In the said embodiment, the cover sensor 26 was mentioned as an example as an example of a support body detection part. However, a sensor that directly detects whether or not the conveyor belt 16 exists in the detection region E may be used. With this configuration, it is possible to execute the contamination determination of the registration sensor 17 in a state where the cover 23 is closed without attaching the belt unit cover 23. For this reason, the influence by disturbance light can be suppressed compared with the structure which performs the stain | pollution | contamination judgment of the registration sensor 17 in the state which opened the cover 23. FIG.

  (5) In the above embodiment, when the conveyor belt 16 is no longer present in the detection area E, the contamination determination of the registration sensor 17 is performed. However, even if the conveyance belt 16 exists in the detection region E, the stain determination of the registration sensor 17 may be performed when the conveyance belt 16 is further away from the registration sensor 17 than during image formation or conveyance of the sheet 3. Good. For example, when the opening amount of the cover 23 is smaller than in the state of FIG. 2, the conveyance belt 16 is slightly included in the detection region E. Even in such a configuration, the reflectance of the conveyor belt 16 is determined in the contamination determination of the registration sensor 17 as compared with the configuration in which the contamination determination of the registration sensor 17 is performed in a state where the conveyance belt 16 is in the same position at the time of image formation. The influence of fluctuation can be suppressed. Alternatively, a sensor that detects the distance between the conveyance belt 16 and the registration sensor 17 may be provided, and the second threshold may be decreased as the detected distance is longer.

  (6) In the above embodiment, the cover 23 and the like are given as an example of the displacement mechanism. However, for example, the conveyance belt 16 may be fixed to the main body case 2 and the registration sensor 17 may be attached to the cover 23 to be displaceable. In short, the displacement mechanism may be a mechanism that changes the distance between them by displacing at least one of the conveyance belt 16 and the registration sensor 17.

  (7) In the above embodiment, it is determined that there is dirt when the amount of light received by the registration sensor 17 is less than the second threshold, in other words, outside the specified range. However, for example, when the light emission control value when the received light amount is set to a predetermined amount is out of a specified range, it may be soiled.

  (8) In the above embodiment, the control circuit 41 is configured to include one CPU 41A and the like. However, the control circuit 41 may have a configuration including a plurality of CPUs, a configuration including a hardware circuit such as an ASIC (Application Specific Integrated Circuit), or a configuration including both the hardware circuit and the CPU.

  DESCRIPTION OF SYMBOLS 1: Printer 2: Main body case 10: Image forming unit 16: Conveying belt E: Detection area 17: Registration sensor 22: Opening part 26: Cover sensor 41: Control circuit

Claims (12)

An image forming unit for forming an image;
An optical sensor having a light emitting element, a light receiving element, and a light transmissive body, emitting light that has passed through the light transmissive body from the light emitting element to a detection region, and receiving light transmitted through the light transmissive body from the detection region;
A reference position for holding a colorant image formed by the image forming unit at least partially included in the detection region, and a support body movable to a position farther from the optical sensor than the reference position;
A carrier detection unit that detects whether the carrier is further away from the optical sensor than the reference position;
When the carrier detection unit detects that the carrier is further away from the optical sensor than the reference position, a light emission control value is given to the light emitting element to emit light of a light amount corresponding to the light emission control value. A light projecting / receiving control unit for emitting and acquiring the amount of light received by the optical sensor;
A stain determination unit that determines that the optical sensor is soiled if the amount of received light obtained when the light emission control value given by the light projection / reception control unit is a predetermined value is outside a specified range; . The printing apparatus according to claim 1,
The printing apparatus, wherein the light projecting / receiving control unit is configured to acquire a received light amount by the optical sensor for light emitted from the light emitting element and diffusely reflected by the carrier disposed at the reference position. The printing apparatus according to claim 1, wherein:
A displacement mechanism is provided that displaces between a first support state in which the carrier is supported at the reference position and a second support state in which the carrier is supported at a position farther from the optical sensor than the reference position. ,
The carrier detection unit is a printing apparatus that detects that the carrier is further away from the optical sensor than the reference position when the displacement mechanism is in the second support state. The printing apparatus according to claim 3,
At least the image forming unit, the optical sensor, and the carrier, and a main body case having an opening,
The displacement mechanism has a cover for holding the carrier, the first support state is a state in which the cover is closed and the opening is closed, and the second support state is a state in which the cover is opened and the opening is opened. A printing apparatus in a state in which a part is opened. The printing apparatus according to any one of claims 1 to 4,
A carrier sensor for detecting whether the carrier is in the reference position;
Before Ki担 bearing member detecting portion, said bearing member based on a detection result of the carrier sensor detects whether away from the optical sensor than the reference position, the printing apparatus. A printing apparatus according to any one of claims 1 to 5,
The printing apparatus, wherein the optical sensor is an infrared sensor in which the light emitting element emits infrared rays and the light receiving element receives infrared rays. The printing apparatus according to any one of claims 1 to 6,
A printing apparatus comprising: a notification unit that notifies a determination result by the stain determination unit. A light-emitting element, a light-receiving element, and a light-transmitting body, which are provided in a printing apparatus having a carrier, emit light that has passed through the light-transmitting body from the light-emitting element to the detection area, and the light-transmitting body is released from the detection area. A method for determining contamination of an optical sensor that receives transmitted light,
A carrier detection step for detecting whether the carrier is further away from the optical sensor than a reference position where at least a part of the carrier is included in the detection region and carries a colorant image; and
When it is detected in the carrier detection step that the carrier is further away from the optical sensor than the reference position, a light emission control value is given to the light emitting element, and a light amount corresponding to the light emission control value is given. Projecting and receiving control step of acquiring the amount of light received by the optical sensor by emitting
An optical sensor comprising: a stain determination step for determining that the optical sensor is dirty if the received light amount obtained when the light emission control value given in the light projecting / receiving control step is a predetermined value is outside a specified range; How to judge dirt. An optical sensor having a light emitting element, a light receiving element, and a light transmissive body, emitting light that has passed through the light transmissive body from the light emitting element to a detection region, and receiving light transmitted through the light transmissive body from the detection region; In a computer having a printing apparatus comprising a carrier,
A carrier detection process for detecting whether the carrier is further away from the optical sensor than a reference position where at least a part of the carrier is included in the detection region and carries a colorant image; and
When the carrier detection process detects that the carrier is farther from the optical sensor than the reference position, a light emission control value is given to the light emitting element, and a light amount corresponding to the light emission control value is given. Projecting and receiving control processing for acquiring the amount of light received by the optical sensor by emitting
A stain determination process for determining that the optical sensor is dirty if the received light amount obtained when the light emission control value given in the light projection / reception control process is a predetermined value is outside a specified range; Dirty judgment program for optical sensors. An image forming unit for forming an image;
An optical sensor having a light emitting element, a light receiving element, and a light transmissive body, emitting light that has passed through the light transmissive body from the light emitting element to a detection region, and receiving light transmitted through the light transmissive body from the detection region;
A reference position for holding a colorant image formed by the image forming unit at least partially included in the detection region, and a support body movable to a position farther from the optical sensor than the reference position;
A carrier detection unit that detects whether the carrier is further away from the optical sensor than the reference position;
When the carrier detection unit detects that the carrier is further away from the optical sensor than the reference position, a light emission control value is given to the light emitting element to emit light of a light amount corresponding to the light emission control value. A light projecting / receiving control unit for emitting and acquiring the amount of light received by the optical sensor;
And a stain determination unit that determines that the optical sensor is dirty if the light emission control value given by the light projection / reception control unit is outside a specified range when the light reception amount is a predetermined amount. . A light-emitting element, a light-receiving element, and a light-transmitting body, which are provided in a printing apparatus having a carrier, emit light that has passed through the light-transmitting body from the light-emitting element to the detection area, and the light-transmitting body is emitted from the detection area A method for determining contamination of an optical sensor that receives transmitted light,
A carrier detection step for detecting whether the carrier is further away from the optical sensor than a reference position where at least a part of the carrier is included in the detection region and carries a colorant image; and
When it is detected in the carrier detection step that the carrier is further away from the optical sensor than the reference position, a light emission control value is given to the light emitting element, and a light amount corresponding to the light emission control value is given. Projecting and receiving control step of acquiring the amount of light received by the optical sensor by emitting
An optical sensor comprising: a stain determination step of determining that the optical sensor is dirty if the light emission control value given by the light projecting / receiving control unit is outside a specified range when the received light amount is set to a predetermined amount; How to judge dirt. An optical sensor having a light emitting element, a light receiving element, and a light transmissive body, emitting light that has passed through the light transmissive body from the light emitting element to a detection region, and receiving light transmitted through the light transmissive body from the detection region; In a computer having a printing apparatus comprising a carrier,
A carrier detection process for detecting whether the carrier is further away from the optical sensor than a reference position where at least a part of the carrier is included in the detection region and carries a colorant image; and
When the carrier detection process detects that the carrier is farther from the optical sensor than the reference position, a light emission control value is given to the light emitting element, and a light amount corresponding to the light emission control value is given. Projecting and receiving control processing for acquiring the amount of light received by the optical sensor by emitting
A stain determination process for determining that the optical sensor is dirty if the light emission control value given by the light projecting / receiving control unit is outside a specified range when the light reception amount is set to a predetermined amount; Dirty judgment program for optical sensors.

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