JP2011123332A - Image forming apparatus, temperature measuring method, and temperature measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of detecting temperature distribution in the axial direction of an image carrier, suppressing the contamination of a temperature measuring means, and performing accurate temperature measurement over the lapse of time while inhibiting a cost increase of the apparatus. <P>SOLUTION: When a rotary polygon mirror 24 and a photoreceptor 1 are driven to be rotated, and when there comes timing that infrared light radiated from one end of the photoreceptor 1 is made incident on a radiation temperature sensor 30, the temperature measurement by the radiation temperature sensor 30 is started so as to detect a temperature at one end of the photoreceptor 1. When the temperature at a point at one end of the photoreceptor 1 is detected, the infrared light radiated from a different position in the axial direction of the photoreceptor 1 is made incident on the radiation temperature sensor 30 so as to detect a temperature at a center side in the axial direction farther than at one end of the photoreceptor 1. Such processing is repeated, and temperatures at a plurality of points in the axial direction at a position in the peripheral direction of the photoreceptor 1 are detected by the radiation temperature sensor 30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile. The present invention also relates to a temperature measuring method and a temperature measuring device for measuring a temperature distribution of a temperature measuring object.

  In an image forming apparatus such as a copying machine, a laser beam printer, or a digital multifunction machine that forms an image by an electrophotographic method, an ozone product generated during charging adheres to the surface of a photoconductor as an image carrier. In particular, in a high humidity environment, there is a known problem that an ozone product adhering to the surface of a photoreceptor adsorbs moisture and an image flow occurs.

  In Patent Document 1, a heater disposed inside a photoconductor is controlled based on a photoconductor surface temperature detected by a temperature sensor arranged close to the surface of the photoconductor so that the temperature of the photoconductor is in a certain range. Thus, an image forming apparatus that prevents an image from flowing is described. In Patent Document 2, the outside air is heated based on the surface temperature of the photoreceptor detected by a temperature sensor, and the heated outside air is passed through the inside of the photoreceptor to control the temperature of the photoreceptor within a certain range. An image forming apparatus for preventing image flow is described.

  In addition, the image forming conditions such as the charging bias, exposure amount, and transfer bias of the photoconductor change depending on the temperature of the photoconductor, and the problem is that image deterioration occurs and the image stability is affected. Is also known. Patent Document 3 describes an image forming apparatus that controls exposure conditions, which are image forming conditions, based on a photoreceptor surface temperature detected by a temperature sensor disposed close to the surface of the photoreceptor.

However, the surface temperature of the photoreceptor may not be uniform, and a temperature difference may occur in the axial direction. Factors that cause the surface temperature of the photosensitive member to have a temperature difference in the axial direction include a distance from a heat source such as a drive motor in the axial direction, and an airflow flowing on the surface of the photosensitive member in the axial direction.
In the image forming apparatuses described in Patent Documents 1 and 2, only one temperature sensor is arranged in the photosensitive member axial direction. Accordingly, when the temperature of the portion facing the temperature sensor on the surface of the photoconductor is different from the portions of the other photoconductors, the image flow may not be suppressed.

  The image forming apparatus described in Patent Document 1 uses a thermopile element as a temperature sensor, detects infrared light emitted from the surface of the photoreceptor, and measures the temperature. However, since the temperature sensor is disposed close to the surface of the photoconductor, toner attached to the surface of the photoconductor adheres to the lens of the temperature sensor, and the infrared light from the photoconductor is obstructed, resulting in a measurement error. There is a fear.

  In the image forming apparatus described in Patent Document 3, a plurality of temperature sensors are arranged in the axial direction of the photoreceptor, and the temperature distribution in the axial direction of the photoreceptor is calculated based on the detection results of the plurality of temperature sensors. . However, in Patent Document 3, in order to calculate the temperature distribution in the photoconductor axis direction, a plurality of temperature sensors are required, leading to a problem that the cost of the apparatus is increased.

  In addition, the problem that a plurality of temperature sensors are required, leading to an increase in the cost of the apparatus, is not limited to detecting the temperature distribution in the axial direction of the photoconductor, but also when detecting the temperature distribution of the temperature measurement object. It can occur as well.

The present invention has been made in view of the above problems, and a first object of the present invention is to detect the temperature distribution in the axial direction of the image carrier while suppressing the cost increase of the apparatus, and to contaminate the temperature measuring means. It is an object of the present invention to provide an image forming apparatus capable of suppressing temperature and performing highly accurate temperature measurement over time.
In addition, the present invention has been made in view of the problems in detecting the temperature distribution of the temperature measurement object, and its second object is to suppress the cost increase of the apparatus and to reduce the temperature distribution of the temperature measurement object. It is to provide a temperature measuring device and a temperature measuring method capable of detecting the temperature.

In order to achieve the above object, the invention of claim 1 includes an image carrier, a light source, and a rotary polygon mirror, and scans the light from the light source onto the image carrier by the rotary polygon mirror. In the image forming apparatus including the writing device for writing a latent image on the image carrier, the infrared light emitted from the image carrier is reflected by the rotary polygon mirror in the writing device. A temperature measuring means for detecting infrared light and measuring the temperature of the surface of the image carrier is provided.
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, based on the response speed of the temperature measuring means, the rotary polygon mirror is rotated to measure the temperatures at a plurality of axial positions on the image carrier. It is characterized by this.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect, a plurality of heat sources are provided in the axial direction inside the image carrier, and the shaft on the image carrier measured by the temperature measuring means. A heat source control means for controlling each heat source based on the temperature at a plurality of directions is provided.
According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the second or third aspect, wherein the image forming condition is controlled based on the temperature at a plurality of axial positions on the image carrier measured by the temperature measuring means. It is characterized by comprising condition control means.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the second to fifth aspects, the temperature at a plurality of axial positions at different positions in the circumferential direction of the image carrier is measured while rotating the image carrier. It is a feature.
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the measurement range of the temperature measuring means at the position of the mirror surface of the rotary polygon mirror is narrower than the mirror surface of the rotary polygon mirror. It is characterized by having comprised as follows.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the temperature measuring means includes at least a thermopile element.
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the temperature measuring means includes an internal temperature detecting means for detecting an ambient temperature of the temperature measuring means, and the internal temperature detecting means detects the temperature. Based on the ambient temperature of the temperature measuring means, the temperature compensation of the cold junction of the thermopile element is performed. The cooling means for cooling the inside of the writing device and the cooling means are the internal temperature detecting means. And a control means for controlling based on the detected ambient temperature of the temperature measuring means.
The invention according to claim 9 detects the temperature of the temperature detection object by detecting the infrared light reflected from the reflecting mirror reflecting the infrared light emitted from the temperature detection object. A temperature detecting device including a temperature detecting means for rotating the reflecting mirror, and changing the temperature detecting portion of the temperature detection object by rotating the reflecting mirror by the rotating means. It is characterized by doing.
Further, the invention of claim 10 is a temperature measurement method for measuring a temperature distribution in the width direction of the temperature detection object, and detects infrared light emitted from the temperature detection object reflected by the reflecting mirror, and determines the temperature. A temperature measurement method in which the first step of detecting and the second step of rotating the reflecting mirror by a predetermined angle are repeatedly performed to measure the temperature distribution in the width direction of the temperature detection object.
The invention of claim 11 is the temperature measuring method of claim 10, wherein the temperature detection object is an image carrier.

According to the image forming apparatus of the present invention, the infrared light reflected from the rotary polygon mirror among the infrared light radiated from the image carrier is detected and the temperature of the image carrier surface is measured. If the surface temperature of the image carrier is detected while rotating the image carrier, the temperature at a plurality of positions in the image carrier axial direction can be detected by a single temperature measuring means. As a result, a plurality of temperature measuring means are arranged in the axial direction of the image carrier, and the cost of the apparatus is suppressed as compared with the case where each temperature measuring means measures the temperature at each position in the axial direction of the image carrier. Is possible.
Further, since the temperature measuring means is provided in the writing device, the temperature measuring means can be prevented from being contaminated with toner or the like as compared with the apparatus in which the temperature measuring means is arranged close to the surface of the image carrier. Accurate temperature measurement can be performed.

  Further, according to the temperature measuring device and the temperature measuring method of the present invention, by rotating the reflecting mirror, the radiation position of the infrared light reflected by the reflecting mirror of the temperature detection object and incident on the temperature measuring means is changed. Is done. Therefore, the temperature distribution in one direction of the temperature detection object can be detected by rotating the reflecting mirror. Thereby, the temperature distribution in one direction of the temperature detection object can be detected by one temperature measurement means, and a plurality of temperature measurement means are arranged in one direction of the temperature detection object, and each temperature measurement means It is possible to suppress an increase in the cost of the apparatus as compared with the apparatus that measures the temperature of the position and detects the temperature distribution of the temperature detection object.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. 1 is a schematic configuration diagram of a writing device. The expansion block diagram around a rotary polygon mirror. The figure explaining the positional relationship of the height direction with the rotary polygon mirror of a radiation temperature sensor. Explanatory drawing of the temperature detection of the photoreceptor by a radiation temperature sensor. (A) is a schematic block diagram which arrange | positioned the radiation temperature sensor adjacent to the rotary polygon mirror. (B) is a schematic block diagram which arrange | positioned the radiation temperature sensor away from the rotating polygon mirror. (A) is a figure which shows the measurement area of a radiation temperature sensor when a radiation temperature sensor is arrange | positioned close to a rotary polygon mirror. (B) is a figure which shows the measurement area of a radiation temperature sensor when a radiation temperature sensor is arrange | positioned away from a rotary polygon mirror. The figure which shows the structure which has arrange | positioned the measurement range limitation member between the radiation temperature sensor and the rotary polygon mirror. The figure explaining the internal diameter of a measurement range restriction member. 1 is an enlarged configuration diagram of a main part of an image forming apparatus according to Embodiment 1. FIG. 3 is a control flow diagram of the first embodiment. FIG. 6 is a control flow diagram of Embodiment 2. 1 is a schematic configuration diagram of a tandem type image forming apparatus. 1 is a schematic configuration diagram of a counter scanning type writing apparatus. FIG. The schematic block diagram of a temperature measuring device.

An embodiment of an electrophotographic printer will be described below as an image forming apparatus to which the present invention is applied.
FIG. 1 is a schematic configuration diagram illustrating a printer 100 according to the present embodiment.
The printer 100 includes a photosensitive member 1 as a latent image carrier, a charging device 2, a developing device 4 as a developing unit, a cleaning device 6 for cleaning the photosensitive member 1, and a writing for writing an electrostatic latent image on the photosensitive member 1. And the like 3. Further, below the photoreceptor 1, a transfer conveyance unit 10 that moves the endless paper conveyance belt 11 endlessly in the clockwise direction in the drawing while being stretched by a plurality of rollers, and a toner image is fixed on the recording paper P. The fixing device 7 is also included.

  Below the transfer / conveying unit 10, there are provided two paper feed cassettes 8 that accommodate a plurality of recording papers P as recording members in a stacked state. By rotating a paper feed roller (not shown), the recording paper P is sent out toward the paper feed path while separating the recording paper P one by one from the paper bundle of the paper feed cassette 8. A registration roller pair 9 is provided near the end of the paper feed path, and the recording paper P in the paper feed path is temporarily sandwiched between the rollers, and the conveyance is temporarily stopped. Then, when the driving of the registration roller pair 9 is resumed at the timing when the toner image formed on the photosensitive member 1 is overlaid by a process described later, it is sent out toward a transfer nip described later.

  When image information is received from a personal computer (not shown) or the like, the photosensitive member 1 is rotated in the clockwise direction in the drawing, and the peripheral surface of the photosensitive member 1 is uniformly charged by the charging device 2. Next, the photoreceptor 1 carries an electrostatic latent image by receiving light scanning based on image information by the writing device 3. This electrostatic latent image is developed with toner supplied from the developing device 4 and becomes a visible toner image.

  A paper transport belt 11 that is moved endlessly below the photoconductor 1 is pressed against the surface of the photoconductor 1 by a transfer roller 5 disposed inside the loop. As a result, a transfer nip is formed in which the photoreceptor 1 and the front surface (loop outer peripheral surface) of the paper transport belt 11 abut. A transfer electric field is formed in the transfer nip by applying a transfer bias to the transfer roller 5.

  The recording paper P sent out from the registration roller pair 9 as described above is brought into close contact with the toner image on the photoreceptor 1 while being sandwiched between the transfer nips. The toner image is transferred by the action of the nip pressure and the transfer electric field. The recording paper P onto which the toner image has been transferred in this manner is conveyed along with the endless movement of the belt while being attracted to the front surface of the paper conveying belt 11 and then delivered to the fixing device 7.

  The fixing device 7 forms a fixing nip with a fixing roller that rotates while including a heat source such as a halogen lamp, and a pressure roller that rotates while being in contact with the fixing roller. The recording paper P delivered from the paper transport belt 11 to the fixing device 7 is sandwiched between the fixing nips. Then, the toner image is fixed on the surface by the action of nip pressure or heating. The recording paper P on which the toner image is fixed in this manner is sent out from the fixing device 7 and then discharged out of the device.

  The transfer residual toner remaining on the surface of the photoreceptor 1 after passing through the transfer nip is removed from the surface of the photoreceptor 1 by the cleaning device 6. Thereafter, the photoreceptor 1 is uniformly charged again by the charging device 2.

  The writing device 3 is covered with an outer case 50, and the outer case 50 is connected to an intake passage 51. The intake passage 51 is a fan that is a blowing unit that blows outside air into the outer case 50. 52 is provided. The writing device 3 is cooled when the outside air is blown to the outer case 50 by the fan 52. That is, the exterior case 50, the intake passage 51, and the fan 52 constitute a cooling unit that cools the writing device 3.

FIG. 2 is a configuration diagram showing the internal configuration of the writing device 3 from above.
A light source unit 20 including a semiconductor laser diode (hereinafter referred to as LD) as a light source is held on a side surface of a housing as a casing of the writing device 3. The light beam 21 emitted from the LD passes through a collimator lens (not shown) of the light source unit 20 and then exits from the light source unit 20. The light beam 21 emitted from the light source unit 20 is shaped into a fixed shape by an aperture (not shown), and then passes through a cylindrical lens 23 so that the sub-scanning direction (in the direction of movement of the surface of the photoreceptor 1 on the surface of the photoreceptor 1). (Corresponding direction). Next, the main scanning direction (the axial direction on the surface of the photosensitive member 1) is reflected while being reflected by any one of the mirror surfaces formed on each of the six side surfaces of the rotating polygon mirror 24 having a regular hexahedron structure rotated at a high speed by a polygon motor (not shown). Direction). Then, an fθ lens 25 for converting the moving speed in the deflection direction of the light beam 21 deflected in the main scanning direction at a constant angular velocity by the rotating polygon mirror 24, a surface tilt correction lens 26 for correcting the surface tilt, After sequentially passing through a folding mirror 27 and a dust-proof glass (not shown) that seals the writing device 3, it is released outside the device and reaches the surface of the photoreceptor 1 (not shown).

  A part of the light beam 21 deflected and scanned by the rotary polygon mirror 24 is reflected by the mirror 28 and detected by the synchronization sensor 29. Based on the timing at which the synchronous sensor 29 detects the light beam 21, the writing start timing in the main scanning direction is determined.

Next, features of the present embodiment will be described.
FIG. 3 is an enlarged configuration diagram around the rotary polygon mirror 24 of the writing device 3.
As shown in the figure, in the vicinity of the rotary polygon mirror 24, there is provided a radiation temperature sensor 30 as temperature measuring means for detecting infrared light and measuring temperature based on the detected amount of infrared light. The radiation temperature sensor 30 includes an angle A connecting a line a from the center of the rotary polygon mirror 24 to the axial center of the photosensitive member 1 and a line b from the center of the irradiation surface of the light beam 21 to the rotary polygon mirror 24. The line c from the center of the measurement surface of the radiation temperature sensor 30 to the rotary polygon mirror 24 and the angle B connecting the line a are arranged at the same angle. Further, the distance between the radiation temperature sensor 30 and the rotary polygon mirror 24 is set as close as possible to the extent that the rotation of the rotary polygon mirror 24 is not hindered. Further, as shown in FIG. 4, the position in the height direction where the radiation temperature sensor 30 is installed is set so that the center of the rotary polygon mirror 24 in the height direction matches the center of the radiation temperature sensor 30 in the height direction.

  In the present embodiment, a thermopile type temperature sensor is used as the radiation temperature sensor 30. The thermopile temperature sensor has a high-speed response with a response speed of several milliseconds to several tens of milliseconds. Note that the response speed is the time required for measurement. Specifically, it is the time required from the start of measurement until the output value corresponds to the temperature of the temperature detection object.

  The thermopile type temperature sensor has a thermopile element in which many thermocouples made of two different metals are connected in series. The thermopile element includes a cold junction and a hot junction, and the thermopile element outputs a voltage proportional to the temperature difference between the cold junction and the hot junction. The cold junction of the thermopile element is brought into contact with a heat sink having a large heat capacity made of an alumina substrate or the like, and the hot junction is brought into contact with an infrared light absorbing member. Infrared light emitted from the photosensitive member 1 reflected from the mirror surface of the rotary polygon mirror 24 enters the infrared light absorbing member via the lens. When infrared light enters the infrared light absorbing member, the temperature of the infrared light absorbing member rises according to the amount of incident infrared light, and a temperature difference according to the amount of infrared light exists between the hot junction and the cold junction. Arise. And the thermoelectromotive force according to the temperature difference generate | occur | produces, and the voltage according to the temperature difference is output to a control part.

  The temperature of the cold junction is affected by the temperature around the temperature sensor, and the temperature difference between the hot junction and the cold junction according to the amount of incident infrared light is affected, so that accurate temperature measurement cannot be performed. For this reason, it is necessary to measure the temperature of the cold junction and compensate the temperature of the cold junction. Therefore, in order to compensate the temperature of the cold junction, a thermistor is provided as an internal temperature detection means for detecting the ambient temperature of the temperature sensor, and by using this thermistor, the output voltage of the thermopile element is corrected, Temperature compensation is performed.

Next, temperature detection of the photoreceptor 1 by the radiation temperature sensor 30 will be described.
FIG. 5 is an explanatory diagram of temperature detection of the photosensitive member 1 by the radiation temperature sensor 30.
In measuring the surface temperature of the photoconductor 1, the printer 100 drives and rotates the rotary polygon mirror 24 and the photoconductor 1 in the same manner as when writing an electrostatic latent image on the charged photoconductor 1. The rotational speed of the rotary polygon mirror 24 is determined according to the response speed of the radiation temperature sensor 30, the number of axial temperature measurements, and the like. The reason why the rotational speed of the rotary polygon mirror 24 is determined based on the response speed of the radiation temperature sensor 30 is that if the rotational speed of the rotary polygon mirror 24 is too high, the output of the radiation temperature sensor 30 changes to the change in the amount of infrared light that changes every moment. The change is not in time, and the measurement error increases. If the rotation of the rotary polygon mirror 24 is slowed, the output change of the radiation temperature sensor 30 can be made to correspond to the change in the amount of infrared light. However, if the rotation of the rotary polygon mirror 24 is too slow, the measurement time becomes long. Occurs. For this reason, by determining the rotation speed of the rotary polygon mirror 24 based on the response speed, the output change of the radiation temperature sensor 30 can correspond to the change of the incident infrared light amount, and the measurement time becomes too long. Can be suppressed. The driving speed of the photosensitive member 1 is determined according to the determined rotational speed of the rotary polygon mirror 24 and the like.

  When the rotational speeds of the rotary polygon mirror 24 and the photosensitive member 1 reach a predetermined specified speed, the light beam 21 is emitted from the LD. Then, temperature measurement of the radiation temperature sensor 30 is started at a predetermined timing after the light beam 21 is detected by the synchronization sensor 29. Specifically, based on the detection result of the synchronous sensor 29, the timing at which the infrared light radiated from the leftmost portion of the photoconductor 1 enters the radiation temperature sensor 30 is measured. The temperature measurement of the radiation temperature sensor 30 is started. When temperature measurement is started, infrared light radiated from the leftmost portion of the photoconductor 1 in the drawing passes through the folding mirror 27, the surface tilt correction lens 26, and the fθ lens 25, and reaches the mirror surface of the rotary polygon mirror 24. The light is reflected and enters the radiation temperature sensor 30. The radiation temperature sensor 30 detects the temperature of the leftmost portion of the photosensitive member 1 in the drawing based on the amount of infrared light emitted from the leftmost portion of the photosensitive member 1 in the drawing. When the temperature at the left end of the photoconductor 1 in the drawing is detected, infrared light radiated from a position different from the axial direction of the photoconductor 1 enters the radiation temperature sensor 30 and is more than the left end of the photoconductor 1 in the drawing. The temperature on the axially central side is detected. Such processing is repeated, and the radiation temperature sensor 30 detects the temperatures at a plurality of axial positions at a certain position in the circumferential direction of the photoreceptor 1. Thereby, the temperature distribution in the axial direction of the photosensitive member can be measured. In addition, the temperature at a plurality of positions in the axial direction at different locations in the circumferential direction is detected over one circumference of the photoreceptor. Thereby, the temperature distribution on the entire surface of the photoreceptor can be measured.

Around the rotary polygon mirror 24, a bearing 24a that rotatably supports the rotary polygon mirror 24, a control unit 24b for controlling the drive of the rotary polygon mirror 24, and the like are disposed. Radiates outside light.
As shown in FIG. 6B, when the radiation temperature sensor 30 is installed at a position away from the rotary polygon mirror 24, the measurement area of the radiation temperature sensor 30 becomes wider than the mirror surface of the rotary polygon mirror 24. As a result, infrared light radiated from the heat generation source (bearing 24 a and control unit 24 b) around the rotary polygon mirror 24 enters the radiation temperature sensor 30. For this reason, the measurement result of the radiation temperature sensor 30 is an average value of the infrared light of the photosensitive member 1 reflected by the rotary polygon mirror 24 and the infrared light of the portion outside the mirror surface of the rotary polygon mirror 24. As a result, a measurement error occurs.
Therefore, as shown in FIG. 6A, the radiation temperature sensor 30 is arranged close to the rotary polygon mirror 24 so that the measurement area of the radiation temperature sensor 30 is narrower than the mirror surface of the rotary polygon mirror 24. Infrared light radiated from the heat source (bearing 24a, control board 24b) around the polygon mirror 24 is suppressed from entering the radiation temperature sensor 30, and the surface temperature of the photoreceptor 1 can be measured with high accuracy. .

FIG. 7A shows a case where the radiation temperature sensor 30 is arranged close to the rotary polygon mirror 24 to narrow the measurement area, and FIG. 7B shows the radiation temperature sensor 30 connected to the rotary polygon mirror 24. This shows a case where the measurement area is widened apart from the above.
As shown in FIG. 7A, when the measurement area is narrowed, infrared light radiated from a narrow area of the photoconductor 1 is measured, and the temperature of the photoconductor 1 can be detected with high accuracy. On the other hand, as shown in FIG. 7B, when the measurement area is widened, infrared light radiated from a wide area of the photoreceptor 1 is measured. In this case, since the average temperature of the wide area of the photosensitive member 1 is obtained, the detection accuracy is lowered. Therefore, it is preferable to arrange the radiation temperature sensor 30 as close as possible to the rotary polygon mirror 24.

In some cases, the radiation temperature sensor 30 cannot be installed close to the rotary polygon mirror 24 due to the layout of the apparatus. In this case, as shown in FIG. 8, the inner peripheral surface is a mirror surface between the rotary polygon mirror 24 and the radiation temperature sensor 30, and the cylindrical measurement range limiting member 31 is used to limit the measurement range. Provide. As shown in FIG. 9, the inner diameter of the measurement range limiting member 31 on the radiation temperature sensor 30 side matches the measurement surface 30 a of the radiation temperature sensor 30, and the inner diameter on the rotary polygon mirror 24 side is the height of the rotary polygon mirror 24. Keep the dimensions below. However, the diameter on the rotary polygon mirror 24 side is the same as or larger than the diameter on the radiation temperature sensor 30 side. This is to prevent infrared light radiated from the radiation temperature sensor 30 from being reflected on the inner peripheral surface of the measurement range limiting member 31 and entering the measurement surface 30a of the radiation temperature sensor 30 to be detected. .
As described above, by providing the measurement range limiting member 31, even when the radiation temperature sensor 30 cannot be installed close to the rotary polygon mirror 24, the measurement area of the radiation temperature sensor 30 is narrower than the mirror surface of the rotary polygon mirror 24. Infrared light other than the infrared light emitted from the photosensitive member 1 can be prevented from entering the radiation temperature sensor 30. Thereby, the surface temperature of the photoreceptor 1 can be measured with high resolution.

  In order to correct the output voltage of the thermopile element, the rotational speed of the fan 52 may be controlled based on the ambient temperature in the writing device 3 detected by the thermistor provided in the radiation temperature sensor 30. That is, when the surface temperature of the photoconductor 1 is not detected, an output signal corresponding to the ambient temperature in the writing device 3 from the thermistor is constantly monitored, and the rotation speed of the fan 52 is based on the output signal from the thermistor. To control. Thereby, it can suppress that the inside of the writing device 3 becomes high temperature.

  Next, control of the image forming apparatus based on the temperature measurement result of the photoreceptor 1 measured using the radiation temperature sensor 30 will be described using an embodiment.

[Example 1]
In the first embodiment, the surface temperature of the photoconductor 1 obtained by the radiation temperature sensor 30 is used to control the temperature of the photoconductor 1 within a certain range, thereby preventing image flow.
In the first embodiment, as shown in FIG. 10, four heaters 41a, 41b, 41c, and 41d are arranged in series in the axial direction inside the photosensitive member. Heater drivers 42a, 42b, 42c, and 42d for controlling the heaters are connected to the heaters 41a to 41d.
The control unit 40 serving as heat source control means includes a memory, a microprocessor, and the like, and the microprocessor performs various processes based on a program stored in the memory. The control unit 40 transmits an ON / OFF signal to each of the heater drivers 42a to 42d at a predetermined timing, and each of the heater drivers 42a to 42d sends a corresponding heater at a predetermined timing based on the received control signal. By switching from ON to OFF and from OFF to ON, control is performed so that the temperature of the surface of the photoreceptor 1 becomes the reference temperature.

FIG. 11 is a control flow diagram according to the first embodiment.
The photoreceptor surface temperature detection mode is executed at a predetermined timing such as when the apparatus is turned on or after a predetermined number of sheets are printed.
When the photosensitive member surface temperature detection mode is executed, the photosensitive member 1 and the rotary polygon mirror 24 are driven to rotate at a specified rotational speed (S101). In the first embodiment, as shown in FIG. 10, a location X1 facing the heater 41a, a location X2 facing the heater 41b, a location X3 facing the heater 41c, a location X4 facing the heater 41d, and 4 locations in the axial direction. The rotational speed of the rotary polygon mirror 24 is adjusted so that it can be detected by the radiation temperature sensor 30.

  Next, when the rotary polygon mirror 24 and the photosensitive member 1 are rotationally driven at a predetermined speed (YES in S102), the light beam 21 is emitted from the LD, and after the light beam 21 is detected by the synchronization sensor 29, a predetermined value is obtained. At the timing, temperature measurement of the radiation temperature sensor 30 is started (S103). In the first embodiment, based on the detection result of the synchronous sensor 29, the measurement is started at the timing when the infrared light emitted from the position in the axial direction X1 on the surface of the photoreceptor 1 enters the radiation temperature sensor 30. Then, infrared light radiated from the position of X1 is incident on the thermopile element of the radiation temperature sensor 30, and an output signal corresponding to the amount of infrared light incident from the thermopile element is transmitted to the control unit 40. An output signal corresponding to the ambient temperature in the writing device 3 is also transmitted from the thermistor arranged in the radiation temperature sensor 30 to the control unit 40. The control unit 40 detects the temperature at the position in the axial direction X1 based on the two output signals from the radiation temperature sensor 30 (the output signal of the thermopile element and the output signal of the thermistor). The control unit 40 receives the output signal of the radiation temperature sensor 30 when the infrared light radiated from the position in the axial direction X2 enters the radiation temperature sensor 30, and performs a second temperature measurement. Thereby, the temperature of the position of X2 is detected. Similarly, the temperature at the position X3 is detected by the third temperature measurement, and the temperature at the position X4 is detected by the fourth temperature measurement.

  Such an operation is performed a plurality of times over the circumference of the photoreceptor. Then, an average temperature at the position in the axial direction X1 is calculated from the temperature measurement results at the positions in the axial direction X1 stored in the memory of the control unit 40. Similarly, the average temperature at the position in the axial direction X2, the position in the axial direction X3, and the position in the axial direction X4 is calculated. Next, the control unit 40 compares the reference temperature stored in advance in the memory with the average temperature at each position in the axial direction, and determines whether or not the average temperature at each position in the axial direction is lower than the reference temperature. Is determined (S104). The control unit 40 transmits a control signal to each heater driver 42a to 42d based on the determination result, and each heater driver 42a to 42d controls each heater 41a to 41d based on the received control signal (S105, 106). For example, if the average temperature in the axial direction X1 is lower than the reference temperature (YES in S104), if the heater 41a is OFF, the heater 41a is turned ON (S105), and the temperature at the position in the photoreceptor axial direction X1 is set. Increase to reference temperature. Further, in the control before the temperature measurement, the temperature at the position in the photoconductor axial direction X1 is likely to be lower than the reference temperature. Therefore, in the ON / OFF control of the heater 41a, the ON time of the heater 41a is lengthened. Or the voltage applied to the heater 41a is increased, and the control condition is changed so that the temperature at the position in the photoconductor axial direction X1 is maintained at the reference temperature. On the other hand, if the average temperature in the axial direction X1 is higher than the reference temperature (NO in S106), if the heater 41a is ON, the heater 41a is turned OFF (S105) and the temperature at the position in the photosensitive member axial direction X1 is set. Reduce to reference temperature. In the control before the temperature measurement, the temperature at the position in the photoconductor axial direction X1 is likely to be higher than the reference temperature. Therefore, in the ON / OFF control of the heater 41a, the ON time of the heater 41a is shortened. Or the voltage applied to the heater 41a is lowered to change the control condition so that the temperature at the position in the photoconductor axial direction X1 is maintained at the reference temperature.

  As described above, in Example 1, since the temperature of the photoconductor 1 is controlled to be the reference temperature at a plurality of positions in the axial direction of the photoconductor 1, the image flow can be suppressed over the entire surface of the photoconductor 1.

  Alternatively, the photosensitive member surface temperature detection mode may be executed when the sheet is between the sheets, and the temperature distribution in the axial direction of the photosensitive member 1 may be examined. In this case, if the temperature detection is performed over the entire circumference of the photosensitive member, the gap between the sheets becomes longer and the productivity is lowered. For this reason, it is preferable to detect the temperature distribution in the axial direction at one place in the circumferential direction of the photoreceptor when the sheet is between the sheets. Alternatively, temperature detection may be performed over the entire circumference of the photosensitive member after the printing operation is completed. Control of each heater 41a-41d based on the temperature distribution detected between the papers is as follows. If the heater is OFF when the temperature is lower than the reference temperature, the heater is turned ON. If the heater is ON when it is higher than the reference temperature, the heater is turned ON. The control of each heater 41a to 41d based on the temperature detection after the end of the printing operation is controlled by changing the voltage applied to the heater or adjusting the heater ON time. You may do it.

  In the above description, the heaters 41 a to 41 d are provided inside the photoconductor 1, but a heater may be provided outside the photoconductor 1. Further, the number of heaters is not limited to four, and two or more heaters may be provided.

[Example 2]
In the second embodiment, the image forming conditions are controlled based on the surface temperature of the photoreceptor 1 obtained by the radiation temperature sensor 30.
In an image forming apparatus in which the surface temperature of the photosensitive member is not controlled to be constant, the optimum image forming condition varies depending on the change in the surface temperature of the photosensitive member.
Therefore, in an image forming apparatus in which the photoreceptor surface temperature is not controlled to be constant, it is preferable to detect the photoreceptor surface temperature and change the image forming conditions based on the detected surface temperature of the photoreceptor 1.

FIG. 12 is a control flow diagram according to the second embodiment.
When a print start is instructed, as in the first embodiment, the control unit, which is an image forming condition control unit, drives the photoreceptor 1 and the rotary polygon mirror 24 to rotate at a specified number of rotations (S201). When the polygonal mirror 24 rotates at a specified rotational speed (YES in S202), temperature measurement by the radiation temperature sensor 30 is started (S203). As in the first embodiment, the number of measurement points in the axial direction of the photosensitive member by the radiation temperature sensor 30 may be four, or more or less. Further, temperature detection may be performed over the entire circumference of the photoconductor, or an axial temperature distribution at one location in the photoconductor circumferential direction may be detected. It is preferable to detect the temperature distribution in the axial direction at one place in the circumferential direction of the photosensitive member because the waiting time until the start of printing is shortened.

Next, when the temperature of the photoreceptor 1 is measured by the radiation temperature sensor 30, the image forming conditions are determined based on the measured temperature (S204). Specifically, the average temperature of the photoconductor 1 is calculated from the temperature measurement value at each position of the photoconductor 1, and the charging bias and the transfer bias are determined based on the calculated average temperature of the photoconductor 1. Further, since the exposure amount can be changed in the photosensitive member axial direction, the exposure amount at each position in the photosensitive member axial direction is determined based on the temperature measurement value at each position.
Next, when the charging bias, the transfer bias, and the exposure amount are determined, the printing operation is started (S205).

  As described above, in Example 2, the temperature of the photosensitive member 1 is measured at a plurality of positions in the photosensitive member axial direction. Therefore, the temperature of the photosensitive member 1 can be obtained with high accuracy and under appropriate image forming conditions. Images can be printed.

  Further, as shown in FIG. 10, even in an image forming apparatus in which a heater or the like is provided inside the photoconductor 1 and the surface temperature of the photoconductor is controlled to be constant, the temperature of the photoconductor 1 immediately after the power is turned on. However, since the temperature is low, the surface temperature of the photosensitive member may be detected before starting printing until the surface temperature of the photosensitive member reaches the reference temperature, and the image forming conditions may be changed based on the temperature detection result. .

  In the present embodiment, the present invention is applied to one monochrome image forming apparatus in which the image forming unit including the photosensitive member 1, the charging device 2, the developing device 4, and the cleaning device 6 is applied. However, the present invention is not limited to this. For example, the present invention is also applied to a color image forming apparatus that forms a tandem image forming unit by arranging four image forming units Y, C, M, and K of magenta, cyan, yellow, and black side by side as shown in FIG. The invention can be applied. This tandem type image forming apparatus is equipped with a counter scanning type writing device 3 and, as shown in FIG. 14, in the vicinity of the rotary polygon mirror 24, there are four radiations corresponding to the image forming units of the respective colors. Temperature sensors 30Y, 30C, 30M, and 30K are provided. This figure is a view of the writing device 3 as viewed from below, and only the K-color radiation temperature sensor 30K and the Y-color radiation temperature sensor 30Y are shown, but the top of the K-color radiation temperature sensor 30K. The M-color radiation temperature sensor 30M is provided, and the C-color radiation temperature sensor 30C is provided on the Y-color radiation temperature sensor 30Y.

  Since the distance from the fixing device and the distance from the motor are different for each photoconductor, the surface temperature of the photoconductor 1 is also different for each photoconductor. Therefore, the surface temperatures of the respective photoreceptors 1Y, 1C, 1M, and 1K are measured by the respective radiation temperature sensors 30Y, 30C, 30M, and 30K, and are described above based on the photoreceptor surfaces detected by the respective radiation temperature sensors 30Y to 30K. By performing the control in the first and second embodiments, a good color image can be obtained.

  In the present embodiment, a thermopile element is used as an element for detecting infrared light radiated from the photoreceptor 1, but a quantum infrared sensor such as a photodiode or a phototransistor may be used.

Next, a temperature measuring apparatus to which the present invention is applied will be described.
FIG. 15 is a schematic configuration diagram of the temperature measuring apparatus 200. As shown in the figure, the temperature measuring apparatus 200 includes an infrared sensor 202 that detects infrared light and a reflecting mirror 201. The reflecting mirror 201 is rotatably supported by the housing of the apparatus. Further, on the surface opposite to the mirror surface of the reflecting mirror 201, a rotating means (not shown) such as an actuator for rotating the reflecting mirror 201 is provided.

  When measuring the temperature distribution in the width direction of the temperature measurement object 203 using the temperature measuring device 200, the reflecting mirror 201 is rotated counterclockwise in the drawing. Then, the position of the infrared light reflected from the reflecting mirror 201 and emitted from the temperature measurement object 203 incident on the infrared sensor 202 changes from the left end in the figure to the right in the figure. A calculation unit (not shown) in the temperature measurement device 200 calculates the temperature at each position of the temperature measurement object 203 based on the output value of the infrared sensor 202. Thereby, the temperature distribution in the width direction of the temperature measurement object 203 can be measured. Further, temperature measurement is performed while moving the temperature measurement object 203 in a direction orthogonal to the scanning direction of the temperature measurement device 200 (left-right direction in the figure) and parallel to the temperature measurement device 200. Thus, the temperature distribution of the entire temperature measurement object 203 can be detected.

  As described above, according to the image forming apparatus of the present embodiment, the photoconductor 1 as an image carrier, the laser diode (LD) as a light source, and the rotary polygon mirror 24 are provided, and the light from the LD is image-held by the rotary polygon mirror 24. A writing device 3 for writing a latent image on the photosensitive member 1 by scanning on the photosensitive member 1 is provided. In the writing device 3, a radiation temperature sensor as temperature measuring means for detecting the infrared light reflected from the rotary polygon mirror 24 from the infrared light emitted from the photosensitive member 1 and measuring the temperature of the surface of the photosensitive member. 30. By rotating the rotary polygon mirror 24, the radiation position of the infrared light reflected on the rotary polygon mirror 24 and incident on the radiation temperature sensor 30 on the surface of the photosensitive member changes every moment. Accordingly, by detecting the surface temperature of the photoreceptor 1 with the radiation temperature sensor 30 while rotating the rotary polygon mirror 24, the temperature distribution in the axial direction of the photoreceptor 1 can be detected. In this way, the temperature distribution in the photoconductor axis direction can be detected with a single temperature sensor, and the cost of the apparatus can be reduced compared to the case where the temperature distribution in the photoconductor axis direction is detected using a plurality of temperature sensors. It can be made cheap. In addition, since the radiation temperature sensor 30 is provided in the writing device 3, it is possible to suppress toner and the like from adhering to the lens of the radiation temperature sensor 30, and good temperature detection can be performed over time.

  Further, according to the image forming apparatus of the present embodiment, since the rotary polygon mirror 24 is rotated based on the response speed of the radiation temperature sensor 30, the output change of the radiation temperature sensor 30 corresponds to the change in the incident infrared light amount. Measurement error can be reduced. Moreover, it can suppress that measurement time becomes long too much.

  Further, according to the first embodiment, as shown in FIG. 10, a plurality of heaters 41 a to 41 d serving as heat sources are provided in the axial direction inside the photoconductor 1, and on the photoconductor 1 measured by the radiation temperature sensor 30. The control part 40 which is a heat source control means which controls each heater 41a-41d based on the temperature of several axial direction of this is provided. As a result, the surface temperature of the photoreceptor 1 can be kept within a predetermined range in the axial direction, and image flow can be suppressed. Moreover, since appropriate temperature control can be performed, power consumption can be suppressed.

  In addition, according to the second embodiment, the controller is provided as image forming condition control means for controlling the image forming conditions based on the temperatures at a plurality of axial positions on the photosensitive member measured by the radiation temperature sensor 30. Thereby, an image can be printed under appropriate image forming conditions.

  Further, the temperature distribution on the entire surface of the photoconductor can be detected by measuring the temperature at a plurality of axial positions on the photoconductor a plurality of times while rotating the photoconductor 1.

  In addition, since the measurement range of the radiation temperature sensor 30 at the mirror surface is narrower than the mirror surface of the rotating polygon mirror 24, infrared light other than infrared light emitted from the surface of the photosensitive member to the radiation temperature sensor 30 is configured. Can be suppressed, and the temperature of the surface of the photoreceptor can be detected with high accuracy.

  The radiation temperature sensor 30 includes at least a thermopile element. Thereby, the temperature of the surface of the photoconductor can be detected from the amount of infrared light radiated from the photoconductor 1. Further, since the thermopile element has a high response speed of several milliseconds to several tens of milliseconds, even if the rotation speed of the rotary polygon mirror 24 is increased, the output change of the radiation temperature sensor 30 is changed to the change in the incident infrared light amount. Can be matched. Thereby, the temperature measurement time of the photoreceptor 1 can be shortened.

  Further, based on the ambient temperature of the radiation temperature sensor 30 detected by the thermistor as an internal temperature detection means for detecting the ambient temperature of the radiation temperature sensor 30 for performing temperature compensation of the cold junction of the thermopile element included in the radiation temperature sensor 30, Controls cooling means for cooling the writing device 3 (comprising an outer case 50, an intake passage 51, and a fan 52). Thereby, it is not necessary to provide a temperature sensor for controlling the cooling means, and the number of parts can be reduced.

  In addition, the temperature measuring apparatus 200 of the present embodiment detects the infrared light reflected from the temperature detection target object 203 and the infrared light reflected from the reflection mirror 201 to detect the temperature detection target. Temperature detection means (infrared sensor 202 and control unit) for detecting the temperature of the object 203 is provided. And the temperature measuring apparatus 200 of this embodiment is provided with the rotation means to rotate the reflective mirror 201, and changes the temperature detection location of the temperature detection target object 203 by rotating the reflective mirror 201 by the rotation means. To do. Accordingly, the temperature distribution in one direction of the temperature detection target object 203 can be detected by one sensor, a plurality of temperature sensors are arranged in one direction of the temperature detection target object 203, and the temperature at each position is detected by each temperature sensor. It is possible to suppress an increase in the cost of the apparatus as compared with the case where the temperature distribution of the temperature detection target object 203 is detected by measuring the above.

  Further, the first step of detecting the infrared light emitted from the temperature detection target 203 reflected by the reflecting mirror 201 and detecting the temperature, and the second step of rotating the reflecting mirror 201 by a predetermined angle, By repeatedly performing the measurement and measuring the temperature distribution in the width direction of the temperature detection target object 203, the temperature distribution in one direction of the temperature detection target object 203 can be detected by one sensor.

1: Photoconductor 3: Writing device 20: Light source unit 21: Light beam 24: Rotating polygon mirror 30: Radiation temperature sensor 31: Measurement range limiting member 40: Control units 41a, 41b, 41c, 41d: Heater 50: Exterior case 52: Fan 200: Temperature measurement device 201: Reflector 202: Infrared sensor 203: Temperature measurement object

JP 2007-156179 A JP 2006-106709 A JP 2008-287220 A

Claims (11)

An image carrier;
An image forming apparatus comprising: a light source; and a rotary polygon mirror, and a writing device that writes a latent image on the image carrier by scanning the light from the light source on the image carrier with the rotary polygon mirror. In the device
The writing device includes temperature measuring means for detecting the infrared light reflected from the rotary polygon mirror among the infrared light emitted from the image carrier and measuring the temperature of the image carrier surface. An image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus characterized in that, based on a response speed of the temperature measuring means, the rotary polygon mirror is rotated to measure temperatures at a plurality of axial positions on the image carrier. The image forming apparatus according to claim 2.
A plurality of heat sources are provided in the axial direction inside the image carrier,
An image forming apparatus comprising heat source control means for controlling each heat source based on the temperature at a plurality of axial positions on the image carrier measured by the temperature measuring means. The image forming apparatus according to claim 2 or 3,
An image forming apparatus comprising image forming condition control means for controlling image forming conditions based on the temperature at a plurality of axial positions on the image carrier measured by the temperature measuring means. The image forming apparatus according to any one of claims 2 to 5,
An image forming apparatus for measuring temperatures at a plurality of axial positions at different positions in the circumferential direction of the image carrier while rotating the image carrier. The image forming apparatus according to claim 1,
An image forming apparatus characterized in that a measurement range of the temperature measuring means at a mirror surface position of the rotary polygon mirror is narrower than a mirror surface of the rotary polygon mirror. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the temperature measuring unit includes at least a thermopile element. The image forming apparatus according to claim 7.
The temperature measuring means includes an internal temperature detecting means for detecting the ambient temperature of the temperature measuring means, and based on the ambient temperature of the temperature measuring means detected by the internal temperature detecting means, the cold junction of the thermopile element Temperature compensation for
Cooling means for cooling the inside of the writing device;
An image forming apparatus comprising: a control unit that controls the cooling unit based on an ambient temperature of the temperature measuring unit detected by the internal temperature detecting unit. A temperature provided with a reflecting mirror that reflects infrared light radiated from a temperature detection object, and temperature detection means that detects the infrared light reflected from the reflecting mirror and detects the temperature of the temperature detection object. In the measuring device,
A temperature measuring device comprising a rotating means for rotating the reflecting mirror, and changing the temperature detection location of the temperature detection object by rotating the reflecting mirror by the rotating means. In the temperature measurement method for measuring the temperature distribution in the width direction of the temperature detection object,
The first step of detecting the infrared light radiated from the temperature detection object reflected by the reflecting mirror to detect the temperature and the second step of rotating the reflecting mirror by a predetermined angle are repeatedly performed to change the temperature. A temperature measurement method for measuring the temperature distribution in the width direction of the detection object. In the temperature measuring method of Claim 10,
The temperature measurement method, wherein the temperature detection object is an image carrier.

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