JP2020076851A - Cooling structure for temperature detection sensor, holder member, and image forming apparatus - Google Patents

Abstract

To devise a cooling structure of a temperature detection sensor using a thermopile element, in order to prevent a foreign substance from being attached to a lens on an apical surface of a casing, while reducing a difference in temperature between the lens and a substrate.SOLUTION: A cooling structure comprises: an air channel 35 in which a temperature detection sensor is arranged; a blower fan that generates an air current in the air channel 35; and a sensor protection wall 51u that accommodates and protects a lens 43 in a casing 41 of the temperature detection sensor. Between the sensor protection wall 51u and a substrate 44, a clearance C1 is formed in the air channel 35 into which an air current flowing from the upstream side of the casing 41 toward the casing 41 flows. On the upstream side of the clearance C1 in the air channel 35, a guide wall 51 is provided which is formed to be closer to a mounting surface of the substrate 44 from the upstream side toward the downstream side of the air channel 35, and blows the air current obliquely to the mounting surface of the substrate 44.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a temperature detection sensor cooling structure, a holder member, and an image forming apparatus.

  Conventionally, an electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a sheet. This fixing device has a heating rotator and a pressure rotator pressed against the heating rotator. In this fixing device, a sheet is passed through a fixing nip portion formed by a heating rotator and a pressure rotator, and heat and pressure are applied to the toner image to melt and fix the toner image on the sheet.

  A temperature detection sensor for measuring the temperature of the heating rotator may be provided on the side of the fixing device. The heating amount of the heating rotator is controlled according to the temperature detected by the temperature detection sensor. Patent Document 1 discloses a non-contact temperature detection sensor as an example.

  This temperature detection sensor has a casing, a thermopile element housed in the casing, a substrate on which the thermopal element is mounted, and a lens attached to the front end surface of the casing. The casing is arranged so that the lens side faces the heating rotator to be detected. The base end side of the casing is closed by the substrate. The lens on the front end surface of the casing transmits the infrared rays emitted from the heating rotator and focuses the infrared rays on the thermopile element.

JP, 2007-316169, A

  In the non-contact type temperature detection unit disclosed in Patent Document 1, if a large difference occurs between the temperature of the cold junction provided near the substrate and the temperature of the lens, infrared rays emitted from the lens are thermopile elements. When the light is received by, an error occurs in the temperature detected by the heating rotator.

  Therefore, it is possible to cool the substrate and the lens to reduce the temperature difference between them by applying cooling air from the side (outside of the casing in the radial direction) toward the temperature detection unit.

  However, in this case, the temperature difference between the substrate and the lens may rather increase depending on the arrangement of the casing.

  That is, it is preferable that the temperature detecting unit further surrounds the front end side of the casing with another member from the viewpoint of preventing foreign matter (dust, scattered toner, etc.) from adhering to the lens. However, in this case, the cooling air only hits the base end side of the casing, and the temperature difference between the lens arranged on the front end surface of the casing and the substrate arranged on the base end side rather increases.

  The present invention has been made in view of the above point, and an object thereof is to reduce the temperature difference between the lens and the substrate while preventing foreign matter from adhering to the lens on the front end surface of the casing. It is in.

A cooling structure according to one aspect of the present invention includes a substrate on which a thermopile element is mounted on a mounting surface, a casing provided on the mounting surface of the substrate to accommodate the thermopile element, and a lens attached to a front end surface of the casing. It is applied to a temperature detection sensor having and.
The cooling structure includes an air passage in which the temperature detection sensor is arranged, a fan that generates an air flow in the air passage, and a sensor protection wall that houses and protects a lens side portion of the casing of the temperature detection sensor. And a gap is formed between the sensor protection wall and the substrate, through which an air flow flowing from the upstream side of the casing toward the casing in the air passage is formed. It is formed on the upstream side of the gap so as to approach the mounting surface of the substrate from the upstream side to the downstream side of the air passage, and guides the airflow so as to obliquely strike the mounting surface of the substrate. A guide surface is provided.

An image device according to another aspect of the present invention includes the above cooling structure.
The image forming apparatus includes an image forming unit that forms a toner image on the sheet, and a fixing device that fixes the toner image on the sheet by passing the sheet between the heating rotator and the pressure rotator. The temperature detection target of the temperature detection sensor is the heating rotator.

A holder member according to another aspect of the present invention is a substrate on which a thermopile element is mounted on a mounting surface, a casing provided on the mounting surface of the substrate for accommodating the thermopile element, and attached to a front end surface of the casing. It is arranged in an air passage through which air flows while holding a temperature detection sensor having a lens.
Then, a substrate facing surface facing the mounting surface of the substrate, a sensor housing recess opening in the substrate facing surface for housing a lens side portion of the casing, and protruding from the substrate facing surface, A protruding seat portion that forms a gap into which air flows between the substrate and the surface facing the substrate by contacting the mounting surface, and a member that holds the substrate in a state where the substrate contacts the protruding seat portion. It is formed on the upstream side of the air passage from the gap and the air gap, and is formed so as to approach the mounting surface of the board from the upstream side of the air path toward the downstream side, and the air flow is oblique to the mounting surface of the board. And a guide surface that guides the user to hit it.

An image forming apparatus according to another aspect of the present invention includes the holder member.
The image forming apparatus includes an image forming unit that forms a toner image on the sheet, and a fixing device that fixes the toner image on the sheet by passing the sheet between the heating rotator and the pressure rotator. The holder member holds the temperature detection sensor, and the temperature detection target of the temperature detection sensor is the heating rotator.

  According to the present invention, it is possible to prevent foreign matter from adhering to the lens on the front end surface of the casing accommodating the thermopile element while reducing the temperature difference between the lens and the substrate.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus including a cooling structure for a temperature detection sensor according to an embodiment. FIG. 2 is a schematic configuration view of the fixing device and its periphery in an enlarged manner seen from the axial direction. FIG. 3 is a schematic sectional view of the temperature detection sensor. FIG. 4 is an external perspective view showing the temperature detection sensor. FIG. 5 is a view in the direction V of FIG. 2 showing the holder member to which the temperature detection sensor is attached. FIG. 6 is a view on arrow VI in FIG. FIG. 7 is an enlarged perspective view showing only the sensor protection portion of the holder member in an enlarged manner. FIG. 8 is a side view showing the positioning pin. FIG. 9 is a sectional view taken along line IX-IX in FIG. FIG. 10 is a view corresponding to FIG. 9 showing a modified example of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments below.

<< Embodiment >>
FIG. 1 shows an example of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 is composed of a laser printer in this embodiment. In the following description, the front side and the rear side mean the front side and the rear side of the image forming apparatus 1 (the front side and the back side in the direction perpendicular to the paper surface of FIG. 1), and the left side and the right side respectively indicate the image forming apparatus. 1 means the left side and the right side as viewed from the front side.

  The image forming apparatus 1 includes a housing 3 that houses the image forming unit 2. A paper feed unit 4 is provided in the lower portion of the housing 3, and a paper discharge unit 5 is formed on the upper surface of the housing 3.

  A plurality of transport roller pairs 7 to 9 that sandwich and transport the paper P are arranged in a paper transport path 6 that extends from the paper feed unit 4 to the paper discharge unit 5.

  The paper feeding unit 4 has a paper feeding cassette 4a and a pickup roller 4b. Sheet-shaped sheets P are stored in the sheet feeding cassette 4a. The pickup roller 4b takes out the paper P in the paper feed cassette 4a and sends it out of the cassette. The paper P sent from the paper feed cassette 4 a to the outside of the cassette is supplied to the image forming unit 2 via the pair of transport rollers 7.

  The image forming unit 2 includes a photoconductor drum 15, a charger 16, an exposure device 17, a developing device 18, a transfer device 19, and a fixing device 30. At the time of image formation, first, the peripheral surface of the photoconductor drum 15 is charged by the charger 16, and then the image data of the document image (for example, the image data of the document image received from an external terminal is displayed on the surface of the photoconductor drum 15 by the exposure device 17. ) Based laser light is irradiated. Then, an electrostatic latent image corresponding to the image data is formed on the surface of the photoconductor drum 15. The electrostatic latent image formed on the surface of the photosensitive drum 15 is developed by the toner charged in the developing device 18. As a result, a toner image is formed (carried) on the surface of the photoconductor drum 15. This toner image is transferred to the paper P by an application bias having a polarity opposite to that of the toner applied to the transfer roller 19a of the transfer device 19. The paper P is a paper supplied from the paper feed cassette 4a. The sheet P after the toner image is transferred is supplied to the fixing device 30 by the transfer roller 19 a and the photoconductor drum 15.

  The fixing device 30 has a heating roller 31 and a pressure roller 32. A heater 31 a is housed inside the heating roller 31 (an example of a heating rotator). A temperature detection sensor 40 is arranged on the lower left side (side) of the heating roller 31. The pressure roller 32 (an example of a pressure rotator) is pressed against the heating roller 31 to form the nip portion N. When the paper P passes through the nip portion N, the paper P is heated and pressed by the heating roller 31 and the pressure roller 32, and the toner image on the paper P is melted and fixed on the paper P. It The paper P on which the toner image is fixed is sent to the downstream side by the heating roller 31 and the pressure roller 32, and is discharged to the paper discharge unit 5 by the plurality of transport roller pairs 8 and 9.

[Structure of the fixing device 30]
Next, the details of the fixing device 30 will be described with reference to FIG. The fixing device 30 is unitized by a housing 33 that houses a heating roller 31 and a pressure roller 32. The housing 33 has a rectangular box shape that is long in the front-rear direction. The lower surface of the housing 33 is formed with a receiving port 33a for receiving the sheet P conveyed along the sheet conveying path 6, and the upper surface of the housing 33 is formed with a sheet discharging port 33b for discharging the sheet P.

  The heating roller 31 transfers heat to the paper P on which the toner image is transferred. The heating roller 31 is rotatably supported by a bearing portion (not shown) provided on the inner wall surface of the housing 33. The heating roller 31 is formed of a metal such as a tubular stainless steel. The heater 31a is composed of, for example, a halogen lamp, and is provided inside the heating roller 31. The heater 31a heats the heating roller 31 from the inside. The heater 31a is not limited to the halogen lamp, but may be a ceramic heater, an IH heater, or the like.

  The pressure roller 32 is arranged parallel to the heating roller 31. The pressure roller 32 is pressed against the pressure roller 32 by a biasing member (not shown), and forms a nip portion N between the pressure roller 32 and the heating roller 31 through which the paper P passes. The pressure roller 32 covers the surface of a cylindrical core metal 34 (only shown in FIG. 3) such as stainless steel, an elastic layer of, for example, silicon rubber formed on the core metal 34, and an elastic layer of silicon rubber. And a layer made of fluororesin or the like.

  At the lower left corner of the housing 33, a chamfered surface 33c is formed over the entire longitudinal direction. A through hole 33d is formed in the chamfered surface 33c at a position facing the central portion of the heating roller 31 in the axial direction.

  A temperature detection sensor 40 for detecting the surface temperature of the heating roller 31 is arranged outside the chamfered surface 33c of the housing 33. The temperature detection sensor 40 faces the heating roller 31 from the diagonally lower side via the through hole 33d.

  The temperature detection sensor 40 is attached to a fixed component (not shown) in the housing 3 while being held by the holder member 50. The holder member 50 is arranged in the air passage 35 together with the temperature detection sensor 40. Then, the temperature detection sensor 40 is cooled by the airflow flowing in the air passage 35. The air passage 35 extends in the front-rear direction on the lower left side of the fixing device 30 in the housing 3. The air passage 35 may be formed by a duct member provided in the housing 3, or may be a gap space intentionally formed between each component device in the housing 3.

  The rear end portion of the air passage 35 (the end portion on the back side of the paper surface of FIG. 2) is connected to a ventilation port formed on the rear side wall of the housing 3. A suction fan 36 for taking in air into the housing 3 is arranged in the ventilation port. The air taken into the housing 3 from the ventilation port flows through the air passage 35 from the rear side to the front side and is then discharged to the outside of the housing 3.

[Configuration of temperature detection sensor]
Next, details of the temperature detection sensor 40 will be described with reference to FIGS. 3 and 4.
The temperature detection sensor 40 includes a casing 41, a thermopile element 42, a lens 43, and a substrate 44. The casing 41 is a cylindrical cap-shaped case that is long in the axial direction and has a base end side that is open. The thermopile element 42 is arranged inside the casing 41. The thermopile element 42 receives the infrared rays emitted from the heating roller 31. The lens 43 is attached to the front end surface of the casing 41. The lens 43 transmits infrared rays emitted from the heating roller 31 and focuses the infrared rays on the thermopile element 42. The thermopile element 42 is formed by connecting a large number of very small thermocouples in series. The output voltage of this thermocouple is proportional to the temperature difference between the hot junction (measurement point) and the cold junction (reference point).
The substrate 44 is arranged so as to close the base end side of the casing 41. The thermopile element 42 is attached to the substrate 44. An IC circuit is mounted on the substrate 44. In this IC circuit, the temperature of the heating roller 31 is calculated based on the infrared rays received by the thermopile element 42. The IC circuit converts the calculated temperature information into a signal and outputs the signal to a control unit (not shown). The control unit acquires the measured temperature of the heating roller 31 based on the signal received from the IC circuit of the substrate 44, and controls the heater 31a to the target temperature based on the acquired measured temperature.

  As shown in FIG. 4, the board 44 has a rectangular plate shape, and a connector 45 for connecting a signal cable is attached to one end of the board 44 in the longitudinal direction. A first positioning hole 44 a is formed between the connector 45 on the board 44 and the casing 41. A second positioning hole 44b is formed on the side of the substrate 44 opposite to the first positioning hole 44a with the casing 41 interposed therebetween. The first positioning hole 44a is a cylindrical through hole, while the second positioning hole 44b is a U-shaped cutout hole.

  The respective positioning holes 44a and 44b of the board 44 are engaged with the two positioning pins 53 (only shown in FIG. 7) assembled on the back surface of the holder member 50, so that the board 44 is held relative to the holder member 50. It is positioned.

[Structure of holder member 50]
As shown in FIGS. 5 and 6, the holder member 50 is roughly composed of a sensor protection portion 51 and a mounting portion 52. The sensor protection part 51 is a part that holds the temperature detection sensor 40 and protects the lens 43 from dust and the like. The attachment portion 52 is a portion for attaching the holder member 50 to a fixed member inside the housing 3. The mounting portion 52 has a cross-shaped positioning protrusion 52a and a mounting hole 52b.

  As shown in FIG. 7, the sensor protection part 51 has a first plate part 51a, a second plate part 51b, a board mounting part 51c, and an inclined surface 51k.

  The first plate portion 51a and the second plate portion 51b intersect each other at an angle of approximately 90 ° and are arranged in an L shape when viewed from the front-rear direction. The board mounting portion 51c is provided between the first plate portion 51a and the second plate portion 51b.

  The board mounting portion 51c has a board facing surface 51d that faces the board 44. A sensor housing recess 51e is formed on the substrate facing surface 51d. The lens-side portion of the casing 41 of the temperature detection sensor 40 is housed in the sensor housing recess 51e.

  As shown in FIG. 5, the sensor housing recess 51e is formed by a sensor protection wall 51u having a U-shaped case when viewed from the side opposite to the substrate 44 side. An opening 51f having a diameter larger than that of the lens 43 is formed in a wall portion of the sensor protection wall 51u that faces the lens 43. Thus, the sensor protection wall 51u is configured to allow infrared rays to enter the lens 43 through the opening 51f while suppressing adhesion of foreign matter (dust or scattered toner) to the lens 43.

  Returning to FIG. 7, pin holes 51j (only shown in FIG. 8) are formed on the front and rear sides of the sensor housing recess 51e in the substrate facing surface 51d. A positioning pin 53 is fitted in each pin hole 51j.

  As shown in FIG. 8, the positioning pin 53 has a columnar pin body 53a and a rectangular column 53b protruding in a key shape on the peripheral surface of the pin body 53a. The rectangular column portion 53b is formed in a portion of the pin body portion 53a near the base end portion. One end surface of the rectangular column portion 53b is in contact with the board facing surface 51d to regulate the insertion amount of the positioning pin 53 into the pin hole 51j. On the other hand, the other end surface of the rectangular column portion 53b comes into contact with the mounting surface of the substrate 44 (the surface on which the thermopile element 42 is mounted), so that the gaps C1 and C2 are formed between the mounting surface and the substrate facing surface 51d (FIG. 9)).

  In addition, rectangular projecting seat portions 51g are formed at both ends of the substrate facing surface 51d in the direction orthogonal to the front-rear direction. The height of the protruding seat portion 51g is equal to the height (axial length) of the rectangular column portion 53b of the positioning pin 53. The protruding seat portions 51g contact the mounting surface of the board 44 to secure gaps C1 and C2 (see FIG. 9) between the mounting surface and the board facing surface 51d.

  Engaging pieces 51h for holding the board 44 are provided upright outside the pair of projecting seat portions 51g on the board facing surface 51d. A claw portion 51i that engages with the end portion of the mounting surface of the substrate 44 and holds the substrate 44 is formed at the tip of the engaging piece 51h.

  An inclined surface 51k is formed on the front side of the substrate facing surface 51d. The inclined surface 51k is formed in a flat surface shape and has an isosceles triangular shape when viewed from the substrate 44 side. Two equal sides of the inclined surface 51k are connected to the first plate portion 51a and the second plate portion 51b, respectively. The remaining one side of the inclined surface 51k is connected to the rear edge of the substrate facing surface 51d. The inclined surface 51k is inclined at a predetermined angle θ1 (see FIG. 9) so that the distance from the rear side to the front side with the substrate 44 (the distance in the direction perpendicular to the substrate 44) decreases. The predetermined angle θ1 is set so that the airflow that hits the mounting surface of the substrate 44 obliquely and bounces off passes through the vicinity of the lens 43 and passes through the opening 51f.

  When the temperature detecting sensor 40 is assembled to the holder member 50, the positioning pins 53 are inserted into the pair of pin holes 51j on the substrate facing surface 51d, as shown in FIG. Then, in this state, the substrate 44 is aligned so that the lens-side portion of the casing 41 of the temperature detection sensor 40 fits inside the sensor housing recess 51e. Then, the first positioning hole 44a and the second positioning hole 44b of the board 44 are externally inserted into the pair of positioning pins 53, and the board 44 is pushed toward the board facing surface 51d side. When the board 44 is pushed until it comes into contact with the rectangular column portions 53b of the pair of positioning pins 53 and the pair of projecting seat portions 51g, the claw portions 51i of the engaging pieces 51h engage with the ends of the board 44. Then, the assembling of the temperature detecting sensor 40 to the holder member 50 is completed, and the state shown in FIG. 6 is obtained. Incidentally, in FIG. 6, the positioning pin 53 is drawn by a two-dot chain line.

FIG. 9 is a sectional view taken along line IX-IX in FIG. As shown in FIG. 9, in the state where the temperature detection sensor 40 is assembled to the holder member 50, between the substrate 44 and the base end surface of the sensor protection wall 51u (which coincides with the substrate facing surface 51d in the present embodiment). The gaps C1 and C2 are secured in.
An outline arrow in FIG. 9 schematically shows an air flow generated in the air passage 35 by the suction fan 36 from the ventilation hole formed in the rear side wall of the housing 3. In the following description, the upstream side and the downstream side mean the air flow passage upstream side (rear side) and the air flow passage downstream side (front side) of the air flow circulating in the air flow passage 35.
The air flow from the upstream side of the air passage 35 toward the casing 41 of the temperature detection sensor 40 changes its direction by the inclined surface 51k and flows into the gap C1. Then, the inflowing airflow is blown obliquely to the mounting surface of the substrate 44, then bounces back, and flows away from the mounting surface of the substrate 44. Then, after passing through the vicinity of the lens 43, this airflow flows out of the sensor housing recess 51e from the opening 51f formed in the sensor protection wall 51u.

  As described above, in the present embodiment, the airflow flowing in the air passage 35 hits the mounting surface of the substrate 44 obliquely, and then bounces and passes near the lens 43. Can be cooled. Therefore, it is possible to accurately detect the temperature of the heating roller 31, which is the detection target.

  That is, in the non-contact type temperature detection sensor 40 including the thermopile element 42, the detected temperature of the heating roller 31 is determined by the amount of infrared rays incident on the thermopile element 42. Therefore, if there is a large difference between the temperature of the substrate 44 (strictly speaking, the temperature of the cold junction (reference point) arranged near the substrate 44) and the temperature of the lens 43 itself, the radiation from the lens 43 occurs. When the thermopile element 42 receives the generated infrared rays, an error may occur in the temperature detected by the heating roller 31.

  On the other hand, in the present embodiment, as described above, the air flow bounces off the substrate 44 and passes near the lens 43. Therefore, both the substrate 44 and the lens 43 are efficiently cooled by the air flow and both The temperature difference can be reduced. Therefore, the error in the temperature detected by the heating roller 31 due to the temperature difference between the substrate 44 and the lens 43 can be reduced.

  The airflow bounced off the mounting surface of the substrate 44 passes through the opening 51f of the sensor protection wall 51u and is discharged to the outside of the sensor housing recess 51e. Therefore, the discharged air acts as a kind of air curtain, and it is possible to prevent foreign matters such as dust and scattered toner from entering the sensor housing recess 51e through the opening 51f. As a result, it is possible to prevent a decrease in temperature detection accuracy due to the foreign matter adhering to the lens 43.

<Modification>
FIG. 10 is a view corresponding to FIG. 9 showing a modified example of the first embodiment. This modification is different from the above embodiment in that an inclined surface 51m different from the inclined surface 51k is further provided. In FIG. 10, the same components as those in FIG. 9 are designated by the same reference numerals, and detailed description thereof will be omitted.

The inclined surface 51m is formed at the end of the portion of the sensor protection wall 51u facing the gap C1 on the sensor housing recess 51e side. The inclined surface 51m extends from the rear side to the front side (from the upstream side of the air passage 35 to the downstream side). It is inclined toward the side) away from the mounting surface of the substrate 44. The inclination angle θ2 of the inclined surface 51m is equal to the inclination angle θ1 of the inclined surface 51k on the upstream side of the gap C1.

  According to this modification, the airflow that has rebounded from the mounting surface of the substrate 44 flows along the inclined surface 51m. Therefore, it is possible to prevent the air flow that has rebounded from the mounting surface of the substrate 44 from being separated at the corners of the sensor protection wall 51u. Furthermore, the bounced airflow can be sufficiently supplied to the vicinity of the lens 43, and the cooling effect of the lens 43 is enhanced as compared with the case where the inclined surface 51m is not provided. Therefore, the same effect as that of the first embodiment can be obtained more reliably.

  The inclination angle of the inclined surface 51m is equal to the inclination angle of the inclined surface 51k on the upstream side of the gap C1. Therefore, the direction of the air flow that bounces off the mounting surface of the substrate 44 and the inclined surface 51m are parallel to each other. Therefore, it is possible to improve the guideability of the airflow by the inclined surface 51m.

<< Other Embodiments >>
In the above-described embodiment and modification, the guide surface for obliquely blowing the air flow onto the mounting surface of the substrate 44 is configured by the inclined surface 51k, but the present invention is not limited to this. The guide surface may be, for example, an arcuate surface that is recessed in an arch shape, or conversely, may be an arcuate surface that bulges toward the air passage 35.

  In the above embodiment, the temperature detection target of the temperature detection sensor 40 is the heating roller 31 of the fixing device 30, but the temperature detection target is not limited to this. The temperature detection target is not limited to the components mounted on the image forming apparatus 1 and may be any object.

  INDUSTRIAL APPLICABILITY As described above, the present invention is useful for a cooling structure for a temperature detection sensor, a holder member for a temperature detection sensor, and an image forming apparatus, and is particularly useful for a printer, a facsimile machine, a copying machine, a multifunction peripheral (MFP), or the like. It is useful when applied to an image forming apparatus.

C1: Gap P: Paper (sheet)
1: Image forming device 2: Image forming unit 3: Housing 30: Fixing device 31: Heating roller 32: Pressure roller 35: Air passage 36: Suction fan (fan)
40: Temperature detection sensor 41: Casing 42: Thermopile element 43: Lens 44: Substrate 50: Holder member 51d: Substrate facing surface 51e: Sensor housing recess 51f: Opening 51g: Projection seat 51h: Engaging piece 51k: Sloping surface (Guide surface)
51m: inclined surface 51u: sensor protection wall

Claims (12)

Cooling of a temperature detection sensor having a substrate on which a thermopile element is mounted on a mounting surface, a casing provided on the mounting surface of the substrate for housing the thermopile element, and a lens attached to a front end surface of the casing. Structure,
An air passage where the temperature detection sensor is arranged,
A fan that produces an air flow in the air passage,
A sensor protection wall for housing and protecting the lens side portion of the casing of the temperature detection sensor,
Between the sensor protection wall and the substrate, a gap is formed in which the airflow flowing from the upstream side of the casing toward the casing flows in the air passage,
It is formed on the upstream side of the gap in the air passage so as to approach the mounting surface of the substrate from the upstream side to the downstream side of the air passage, and the air flow is oblique to the mounting surface of the substrate. Cooling structure for the temperature detection sensor, which is provided with a guide surface that guides it against the temperature. The cooling structure for the temperature detection sensor according to claim 1,
The guide surface is configured to guide the airflow such that the contact angle of the airflow with respect to the mounting surface of the substrate is a predetermined angle,
The predetermined angle is a cooling structure for a temperature detection sensor, in which an airflow that hits the substrate obliquely and bounces back passes through the vicinity of the lens. The cooling structure for a temperature detection sensor according to claim 2,
An opening through which infrared rays pass is formed in the wall portion of the sensor protection wall facing the lens,
The predetermined angle is a cooling structure for a temperature detection sensor, wherein the airflow that obliquely hits the substrate and bounces back passes through the vicinity of the lens and then passes through the opening. The cooling structure for the temperature detection sensor according to claim 1,
The cooling structure for the temperature detection sensor, wherein the guide surface is a flat-surface-shaped inclined surface formed so as to approach the mounting surface of the substrate from the upstream side to the downstream side of the air passage. The cooling structure for the temperature detecting sensor according to claim 1,
The corner portion on the casing side of the portion facing the gap in the sensor protection wall is inclined from the upstream side of the air passage toward the downstream side, away from the mounting surface of the substrate, the cooling structure of the temperature detection sensor. .. An image forming apparatus comprising the cooling structure for a temperature detection sensor according to claim 1.
An image forming unit that forms a toner image on the sheet, and a fixing device that fixes the toner image on the sheet by passing the sheet between the heating rotator and the pressure rotator,
An image forming apparatus in which the temperature detection target of the temperature detection sensor is the heating rotating body. In a state of holding a temperature detection sensor having a substrate on which a thermopile element is mounted on a mounting surface, a casing provided on the mounting surface of the substrate to accommodate the thermopile element, and a lens attached to a front end surface of the casing. A holder member arranged in an air passage through which air flows,
A board facing surface facing the mounting surface of the board,
A sensor accommodating recess for accommodating the lens side portion of the casing, which is opened in the substrate facing surface,
A protruding seat portion that is provided so as to project from the substrate facing surface and forms a gap into which air flows between the substrate and the substrate facing surface by contacting the mounting surface of the substrate;
An engagement piece for holding the substrate in a state where the substrate is in contact with the protruding seat portion,
It is formed on the upstream side of the air passage with respect to the gap, and is formed so as to approach the mounting surface of the substrate from the upstream side of the air passage toward the downstream side, and the airflow is obliquely applied to the mounting surface of the substrate. A holder member having a guide surface for guiding. The holder member according to claim 7,
The guide surface is configured to guide the airflow such that the contact angle of the airflow with respect to the mounting surface of the substrate is a predetermined angle,
The predetermined angle is a holder member in which the airflow that hits the substrate obliquely and bounces back passes through the vicinity of the lens. The holder member according to claim 8,
An opening through which infrared rays pass is formed in a portion of the wall surface of the sensor housing recess facing the lens,
The above-mentioned predetermined angle is a holder member in which the airflow that hits the substrate obliquely and bounces back passes through the vicinity of the lens and then further passes through the opening. The holder member according to any one of claims 7 to 9,
The holder member, wherein the guide surface is a flat surface-shaped inclined surface formed so as to approach the mounting surface of the substrate from the upstream side to the downstream side of the air passage. The holder member according to any one of claims 7 to 10,
A holder member in which a casing-side end of a portion of the board facing surface facing the gap is inclined away from the mounting surface of the board from the upstream side to the downstream side of the air passage. An image forming apparatus comprising the holder member according to claim 7.
An image forming unit that forms a toner image on the sheet, and a fixing device that fixes the toner image on the sheet by passing the sheet between the heating rotator and the pressure rotator,
The temperature detection sensor is held in the holder,
An image forming apparatus in which the temperature detection target of the temperature detection sensor is the heating rotating body.

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