JP4628540B2 - Infrared temperature sensor - Google Patents

Description

[0001]
[Industrial application fields]
The present application relates to an infrared temperature sensor that detects, in a non-contact manner, the surface temperature of a rotating body such as a heat fixing roller for fixing an unfixed toner image on a sheet in a fixing device such as a copying machine.
[0002]
[Prior art]
Conventionally, as a temperature sensor for detecting the surface temperature of a rotating body such as a heat fixing roller used in a fixing device of a known copying machine, a contact type temperature sensor for detecting a temperature by bringing a thermal element into contact with the roller surface is mainly used. Have been used. Although this type of contact-type temperature sensor has the advantage that it can accurately detect the surface temperature of the roller, the mounting member or the thermal element touches the roller surface because the mounting member of the thermal element is pressed against the roller surface at a constant pressure. There was a fault to hurt.
[0003]
In addition, the use of a material with high wear resistance that can withstand long-term use as a mounting member, and a material such as a spring material that presses the thermosensitive element against the roller at a constant pressure increases the heat capacity of the thermosensitive element part, and the desired heat There were drawbacks such as inability to obtain response characteristics.
[0004]
As means for solving such drawbacks, the present applicant has proposed an infrared temperature sensor for detecting the surface temperature of a roller or the like in a non-contact manner in Japanese Patent Application Laid-Open No. 11-223555.
This infrared temperature sensor has an infrared reflecting surface on at least an inner surface, a holding body having an opening for incident infrared light at one end, and a resin film made of a polymer material disposed at the other end of the holding body, The thermosensitive element fixed so as to be in close contact with the resin film, and the temperature compensating thermosensitive element for detecting the ambient temperature including the holding body.
[0005]
The polymer film constituting the resin film is made of polyester, polyimide, or a material in which carbon black or an inorganic pigment (one or more of chrome yellow, petal, titanium white, ultramarine) is mixed and dispersed. Yes.
The infrared temperature sensor having the structure as described above has an absorption characteristic of the resin film when infrared rays radiated from the roller surface enter the opening at one end of the holding body and reach the resin film surface disposed on the other end side. The temperature of the film rises by absorbing infrared light having a wavelength corresponding to the spectrum.
[0006]
This temperature rise is detected by an infrared detecting thermal element that is tightly fixed to the resin film. In addition, since the temperature of the holding body also rises due to the radiant heat from the object to be detected and the ambient atmosphere temperature, the temperature compensation thermal element arranged on the resin film near the holding body causes the temperature fluctuation of the holding body and the heat radiation around the sensor. It is configured to detect the temperature change due to the influence of convection and to compensate for the temperature change, thereby increasing the detection sensitivity.
[0007]
For example, as shown in FIG. 6, the temperature detection circuit of the infrared temperature sensor includes a series circuit in which an infrared detection thermal element 6 and a resistor are connected between a power source V and the ground, and similarly a power source V and It consists of a series circuit in which a temperature-compensating thermal element 7 and a resistor are connected between grounds, and the connection point between each of the resistors and the thermal elements 6 and 7 is connected to the CPU through a resistor R and an A / D converter. It has been.
[0008]
The CPU A / D converts and takes in the voltage appearing at the connection point between the infrared detecting thermal element 6 and the resistor and the voltage appearing at the temperature compensating thermal element 7 and the resistor as measurement output voltages, The temperature data ΔT of the difference between the infrared detecting thermal element 6 and the temperature compensating thermal element 7 is calculated by converting into temperature data of the infrared detecting thermal element 6 and the temperature compensating thermal element 7. Then, the surface temperature T of the detected object (roller) is detected by comparing these calculated data (temperature data ΔT) with the data in the data table stored in advance in the RAM or ROM, and the display DIS is used as the detected temperature. Is displayed.
[0009]
[Problems to be solved by the invention]
However, the infrared temperature sensor holder is manufactured using a cutting method or a die-cast method. However, the area of the opening due to variations in processing and mold dimensions at the time of manufacture, from the tip of the opening to the film surface. A slight variation occurs in the dimensional distance.
Further, the material and thickness of the resin film also vary between product lots, and the dimensions of the thermal element placed on the resin film also vary depending on the manufacturing process of cutting. There are also variations during assembly.
[0010]
Thus, each variation of each member which comprises an infrared temperature sensor appears as a fluctuation | variation of an output characteristic by each completed infrared temperature sensor. Conventionally, in order to correct such variations in output characteristics, the output characteristics are corrected by adjusting the detection circuit and the like after each infrared temperature sensor is assembled in each machine.
[0011]
However, this method requires adjustment of the circuit for each machine to which the sensor is attached and requires some know-how for adjustment. There was a problem in terms of mass productivity.
[0012]
Therefore, the present invention has been made to solve the above problems, and adjustment after the infrared temperature sensor is incorporated in the detection circuit becomes simple or unnecessary, and is excellent in terms of shortening the working time and mass productivity. An object is to provide an infrared temperature sensor.
[0013]
[Means for Solving the Problems]
The present invention provides an infrared temperature sensor having a cylindrical light guide part, including a shielding part provided so as to protrude inside the light guide part, and the shielding part is provided inside the light guide part. A bar-like protruding portion that is fixed to the light guide portion so that the protruding distance is adjustable and is fixed to the light guide portion with an adhesive after the protruding distance is adjusted. It is what you have.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiments of an infrared temperature sensor according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view showing Embodiment 1 of an infrared temperature sensor according to the present invention.
2 is a longitudinal sectional view in the longitudinal direction of the infrared temperature sensor A shown in FIG. In FIG. 1, the infrared temperature sensor A is a light guide whose opening 1 has a horizontally long shape or an elliptical shape (the shape of the opening can be selected according to conditions such as the size, shape, distance to the sensor, etc. of the detected object). It consists of a holding body 3 having a part 2. The light guide 2 and the holding body 3 are made of a metal material having a high thermal conductivity such as aluminum and a low thermal emissivity.
[0018]
The inner surface of the light guide 2 may be polished as necessary to increase the reflectance of infrared rays, or an infrared absorption film that absorbs infrared rays may be provided. When the infrared temperature sensor A is used in a fixing device or the like, the influence of the scattered toner on the output signal of the infrared temperature sensor A can be reduced by providing an infrared absorption film.
[0019]
As a material for the infrared absorbing film, for example, a black body absorbing film having an emissivity of 0.94 or more is preferable. As other means, an effect equivalent to that of the infrared absorption film can be obtained even if anodizing treatment or alumite treatment is performed. The light guide itself may be formed of plastic resin, and an infrared absorption layer may be provided on the inner surface thereof, or a metal layer that reflects infrared light may be provided on the inner surface of the light guide portion 2 made of plastic resin. .
[0020]
On the outer surface of the light guide portion 2, a protruding portion 4 that protrudes inside the light guide portion 2 is provided as a shielding portion that adjusts the amount of incident infrared rays. The protrusion 4 may be a variable (variable protrusion) that can variably adjust the protrusion distance B, such as a screw. In this embodiment, a hexagon socket set screw (M3, length 5 mm) was used as the protrusion.
[0021]
Further, the protruding portion 4 is not limited to a variable one such as a screw, but is fixed (fixed protruding portion) such as a rivet 12 or a plate-like body 13 as shown in FIGS. Of course, an aperture unit of a camera may be used.
[0022]
The resin film 5 has a wiring pattern formed on one surface, and the infrared detecting thermal element 6 and the temperature compensating thermal element 7 are electrically connected to the wiring pattern. An external lead terminal is formed at the end of the wiring pattern. The infrared detecting heat-sensitive element 6 is placed at a substantially central portion of the resin film 5 so as to be disposed on the surface of the resin film 5 on the space portion side opposite to the infrared incident side.
[0023]
The temperature compensating thermosensitive element 7 is placed near the end of the resin film 5.
The resin film 5 on which the infrared detecting thermal element 6 and the temperature compensating thermal element 7 are thus mounted is attached so as to be in close contact with the other end opening of the light guide 2 of the holding body 3, and the lid member 8. It is configured to be fixed with.
[0024]
As a result, the infrared detecting thermal element 6 is arranged so as to be positioned substantially at the center of the light guide 2. The temperature compensating thermosensitive element 7 is disposed inside the holding body and the lid member 8 and detects the ambient temperature of the infrared temperature sensor A. A space portion 10 is formed on the lid member side of the resin film 5 on which the infrared detecting thermal element 6 is placed.
[0025]
A space 11 is also formed in the lid member 8 and the holding body 3 corresponding to the resin film 5 on which the temperature compensating thermosensitive element 7 is placed. Reference numeral 9 denotes a mounting hole for the infrared temperature sensor A. A thin film thermistor is suitable as the infrared detecting thermal element 6 and the temperature compensating thermal element 7, but is not limited thereto.
[0026]
The resin film 5 is made of a polymer material such as Teflon, silicon, polyimide, polyester, polyethylene, polycarbonate, or PPS (polyphenylene sulfide), but may be any material that absorbs infrared light. The materials may be used.
[0027]
Furthermore, carbon black or an inorganic pigment (one or more of chrome yellow, petal, titanium white, and ultramarine) can be mixed and dispersed in these resins to use a material that can absorb infrared rays of almost all wavelengths. Moreover, in order to reflect the heat radiated | emitted from the resin film 5 and to raise detection sensitivity, you may provide an infrared reflective film in the back surface of the resin film 5, or the wall surface of the space part 10 behind it.
[0028]
The lid member 8 is made of a metal having a high thermal conductivity such as aluminum and a low thermal emissivity, like the holding body 3. The inner wall of the space portion 10 on the inner surface may be polished as necessary to increase the infrared reflectance, or the lid member 8 itself is made of resin and actively reflects infrared rays on the inner surface. A metal layer may be provided.
[0029]
Next, a method for adjusting the amount of incident infrared rays by the protruding portion 4 protruding from the inner surface of the light guide portion 2 will be described.
Using a measuring device with a blackbody furnace installed, an infrared temperature sensor is set at a position 5 mm away from the surface of the blackbody furnace. The measurement is performed, for example, with a temperature detection circuit shown in FIG. The surface temperature of the black body furnace is controlled to be maintained at a constant temperature (for example, 180 ° C.). The protrusion distance B of the protrusion 4 provided in the light guide part of the set infrared temperature sensor is set to 0 mm (a state in which the protrusion does not protrude into the light guide part).
[0030]
The output voltage of the infrared detection thermal element 6 and the temperature compensation thermal element 7 when the output of the temperature compensation thermal element 7 reaches an arbitrary temperature (for example, 80 ° C.) is input to the detection circuit, and the input data Is converted into temperature data by a temperature calculation circuit, and a data table stored in advance is collated to detect the surface temperature (detected temperature) of the black body furnace.
[0031]
Next, the protrusion 4 is protruded into the light guide 2 by an arbitrary distance, and the surface temperature is detected by the same method as described above. In this way, the detected temperature is measured while changing the protruding distance, and the relationship between the protruding distance B of the protruding portion and the detected temperature is obtained.
FIG. 7 is a graph showing the relationship between the protrusion distance B obtained using a hexagon socket set screw (M3, length 5 mm) as the protrusion 4 and the detected temperature. It can be seen that the detection temperature decreases because the amount of incident infrared light decreases as the screw protrusion distance B increases.
[0032]
The relationship between the protruding distance B of the protruding portion and the detected temperature is obtained in advance by the method as described above. Next, adjustment of an unadjusted infrared temperature sensor will be described. In the same manner as described above, an unadjusted infrared temperature sensor is set in a measuring apparatus composed of a black body furnace maintained at a constant temperature (180 ° C.). In this case, the protrusion distance B of the protrusion is set to 0 mm. The detection temperature is measured through the detection circuit from the output of the infrared detection thermal element 6 when the output of the temperature compensation thermal element 7 reaches a temperature of 80 ° C.
[0033]
For example, when the detected temperature measured from FIG. 7 is 186 ° C. when the protrusion distance is 0 mm, in order to adjust the detected temperature of the unadjusted infrared temperature sensor to 180 ° C. which is the temperature of the black body furnace, It can be seen from the curve a in FIG. 7 that the protrusion distance B should be 4.0 mm. It is desirable to re-measure the adjusted infrared temperature sensor and confirm the detected temperature. Thereafter, the protrusion is fixed by a method such as an adhesive, and the adjustment of the infrared temperature sensor is completed.
[0034]
The adjustment method described above is a method using a screw as the projecting portion 4, but if the distance B to be projected in advance can be determined from FIG. 7, several types of rivets 12, plates 13 or spring pins having different lengths are prepared. The rivet, spring pin, or plate-like member having a prescribed dimension can be easily adjusted by projecting the light guide section 2 as a fixed projecting section. The material may be anything other than metal as long as it blocks the incidence of infrared rays, such as resin or ceramic with good thermal conductivity.
[0035]
Although not shown in the embodiment of the present application, as a method of adjusting the amount of infrared rays, there is a method of attaching a U-shaped plate spring material to the light guide unit 2 so as to cover a part of the opening 1. .
[0036]
Further, as shown in FIG. 8, the same effect can be obtained by providing a movable wall 15 that can adjust the distance between the wall surface of the space portion 10 of the lid member 8 and the resin film 5 with a screw 14. That is, by turning the screw 14 toward the inside of the space 10, the movable wall 15 provided at the tip of the screw 14 is pushed forward, and the distance between the movable wall 15 and the resin film 5 is reduced. In this method, it is possible to use a screw 14 having a large diameter instead of the movable wall 15 and reduce the distance between the tip and the resin film 5 on the screw 14 (distance between the film in the space and the wall surface). Decreasing the value decreases the output).
[0037]
FIG. 5 shows a conceptual diagram of mounting when the infrared temperature sensor A shown in FIG. 1 is used in a fixing device. Since the light guide 2 of the infrared temperature sensor A has a horizontally long opening along the axial direction of the heat fixing roller R, the heat emitted from the heat fixing roller R can be efficiently captured. .
[0038]
Infrared radiation radiated from the surface of the heat fixing roller R is incident from the opening 1 of the light guide portion 2 and reaches the resin film 5 where it is absorbed by the resin film 5 and converted into heat. Since this heat is transmitted to the infrared detecting thermal element 6, the temperature of the infrared detecting thermal element 6 rises.
[0039]
The output due to the resistance change of the infrared detecting thermosensitive element 6 due to the temperature rise and the output detected by the temperature compensating thermosensitive element 7 are detected, and the set temperature and output signal stored in the memory in the CPU in the detection circuit in advance are detected. The surface temperature of the object to be detected is detected from the data table and a control signal is output to control the temperature.
[0040]
Embodiment 2. FIG.
Although the above embodiment has described an example of an infrared temperature sensor for detecting the temperature of a heat fixing roller of a fixing device such as a copying machine, the present invention is not limited to this. For example, it can be applied to a structure having a waveguide for guiding infrared light to an infrared sensor such as a thermopile infrared sensor such as a radiation thermometer or an ear thermometer, a pyroelectric infrared sensor, or a bolometer. That is, the amount of infrared rays can be adjusted by providing a protruding portion such as a screw or the like in the waveguide portion as in the present invention, and the detection temperature of the infrared sensor can be easily adjusted.
[0041]
As described above, by providing a protrusion that protrudes into the light guide 2 on the outer surface of the light guide 2 of the infrared temperature sensor A, the protrusion distance of the protrusion can be adjusted. Since it is possible to produce an infrared temperature sensor A with uniform output characteristics by correcting variations in the detection temperature of each infrared temperature sensor A, adjustment after the infrared temperature sensor A is incorporated in the detection circuit becomes simple or unnecessary. The infrared temperature sensor A can be provided which is excellent in terms of shortening the working time and mass productivity.
[0042]
【The invention's effect】
According to this invention, in the infrared temperature sensor having a cylindrical light guide part, the infrared temperature sensor has a shield part provided so as to protrude inside the light guide part, and the shield part is located inside the light guide part. A bar-shaped protrusion that is fixed to the light guide unit at an arbitrary position so that the protrusion distance to the light source can be adjusted and is fixed to the light guide unit with an adhesive after the protrusion distance is adjusted. By having the portion, there is an effect that the variation in the sensor output characteristics after the sensor assembly can be easily adjusted.
[Brief description of the drawings]
FIG. 1 is a perspective view of an infrared temperature sensor according to the present invention.
2 is a longitudinal sectional view of the infrared temperature sensor in FIG. 1. FIG.
FIG. 3 is a longitudinal sectional view of the infrared temperature sensor when a rivet is used as a protrusion in the infrared temperature sensor shown in FIG.
4 is a longitudinal sectional view of an infrared temperature sensor when a plate-like body is used as a protrusion in the infrared temperature sensor shown in FIG. 1. FIG.
FIG. 5 is a conceptual diagram of mounting when the infrared temperature sensor shown in FIG. 1 is used in a fixing device.
FIG. 6 is a configuration diagram of a temperature detection circuit according to a conventional infrared temperature sensor.
FIG. 7 is a graph showing the relationship between the protruding distance of the infrared temperature sensor and the detected temperature.
FIG. 8 is a longitudinal sectional view of an infrared temperature sensor when the wall surface of the space is a movable wall surface.
[Explanation of symbols]
A Infrared temperature sensor 1 Opening 2 Light guide 3 Holding body 4 Screw (variable protrusion)
5 Resin film 6 Infrared detection thermal element 7 Temperature compensation thermal element 12 Rivet (fixed protrusion)
13 Plate (fixed protrusion)
15 Movable wall

Claims (1)

In an infrared temperature sensor having a cylindrical light guide,
A shielding portion provided so as to protrude inside the light guide portion;
The shielding part is an adhesive to the light guide part after the projecting distance is adjusted at any location fixed to the light guide part so that the projecting distance to the inside of the light guide part can be adjusted. infrared temperature sensor, characterized in secured to unadjustable, that it has a projecting portion of the rod-shaped.

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