JP2007033190A - Humidity detection device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a humidity detection device and an image formation device manufacturable inexpensively, having excellent energy efficiency. <P>SOLUTION: The humidity detection device has a characteristic wherein a fiber whose thickness is changed corresponding to a surrounding environmental humidity is arranged between a light emitting element and a light receiving element, and the humidity is detected by a change of transmitted light quantity through the fiber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a humidity detection apparatus and an image forming apparatus that detect humidity in the atmosphere based on changes in transmitted light.

  Conventionally, as a humidity sensor, a method using a change in electric resistance or the like of a hygroscopic substance is known. As shown in FIG. 10 (a), a polymer or ceramic as a hygroscopic material is formed on the substrate 1 on which the comb-shaped electrode 2 is formed, or the polymer or ceramic as shown in FIG. 10 (b). A sandwich-type element is produced in which a hygroscopic material 3 made of the above is sandwiched by electrodes 4 formed by vapor deposition or the like. The humidity is detected by measuring the change in electrical resistance or capacitance between the electrodes due to moisture adsorption and desorption.

Moreover, as a humidity sensor using light, patent document 1, patent document 2, patent document 3, patent document 4, and patent document 5 are proposed.
Japanese Examined Patent Publication No. 6-90139 Japanese Patent Laid-Open No. 56-67738 JP-A-56-110039 Japanese Unexamined Patent Publication No. 63-19539 JP 59-204742 A

  As described above, the method using the change in the electrical resistance or the like of the hygroscopic substance needs to form comb-shaped electrodes on the substrate in advance or form electrodes on both sides of the hygroscopic substance by vapor deposition or the like. . When ceramic is used as the hygroscopic substance, it is necessary to periodically remove the adsorbed substance by heating with a heater or the like in order to recover sensitivity.

  There was also a problem of high cost. Moreover, in the proposal of patent document 1, what formed the functional pigment | dye film | membrane on transparent substrates, such as glass, is installed between the light source and the light-receiving part. In the proposal of Patent Document 2, a moisture-sensitive resin in which the number of light absorption systems changes is interposed between the light receiving element and the light emitting element. In the proposal of Patent Document 3, a lens or a laser is used. The proposal of patent document 4 is a structure which uses a tungsten lamp for a light source and heats a light transmission film with a heater. Both can be expensive. According to the proposal of Patent Document 5, irregular reflection is detected using a reflection type sensor, so it is necessary to increase the amount of light emitted from the light emitting source, and there is a possibility that the energy efficiency is poor.

  The present invention was made by paying attention to the problems of the related art, and is intended to detect humidity by utilizing the action of changing the fiber diameter and the fiber thickness due to moisture adsorption and desorption, An object of the present invention is to provide a humidity detecting device and an image forming apparatus that can be manufactured at low cost simply by placing the fibers between the light emitting element and the light receiving element and have high energy efficiency because they are configured to transmit light. .

  The present invention can solve the above problems by providing the following configuration.

  (1) It is characterized in that a fiber whose thickness changes according to the surrounding environmental humidity is arranged between the light emitting element and the light receiving element, and the humidity is detected by a change in the amount of transmitted light of the fiber. Humidity detection device.

  According to the first invention of the present application, a fiber whose thickness changes according to the ambient environmental humidity is disposed between the light emitting element and the light receiving element, and the humidity is detected by a change in the amount of transmitted light of the fiber. Therefore, an inexpensive and stable humidity sensor can be configured.

  According to 2nd invention which concerns on this application, the said fiber is 1st sheet | seat of the mesh shape which knitted the direction of the fiber at the fixed angle, and 2nd knitted at the angle different from the direction of the fiber of the 1st sheet | seat. By stacking sheets, it is possible to provide a humidity detection device in which the output voltage changes greatly with respect to humidity.

  According to the third invention of the present application, the light emitting element and the light receiving element that are mounted on the substrate in advance are mounted with an integrated unit that incorporates a fiber whose thickness changes according to the ambient environmental humidity. By doing so, it is possible to provide a humidity sensor with less man-hours and lower costs.

  According to the fourth invention of the present application, the light emitting element and the light receiving element, the fiber and the peripheral circuit are integrally formed on the substrate, and the resistance value of the peripheral circuit is adjusted, thereby suppressing variations and stabilizing. A humidity detection device can be provided.

  According to the fifth aspect of the present application, since the resistance value is adjusted using a variable resistor, it is possible to provide a stable humidity detecting device with little variation.

  According to the sixth aspect of the present application, since the resistance value is adjusted by the chip resistance, it is possible to provide a stable and inexpensive humidity detecting device with little variation.

  According to the seventh invention of the present application, since the wavelength of the light emitting element is infrared, it is possible to provide a humidity detection device that is not easily affected by external light.

  According to the eighth aspect of the present application, it is possible to provide an image forming apparatus that can be made cheaper than before by including an inexpensive humidity detection device.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
First, a first embodiment to which the present invention is applicable will be described with reference to FIGS.

  FIG. 1 is an explanatory diagram showing the basic configuration of the present invention.

  32 is a light emitting diode (hereinafter referred to as LED), 33 is a photodiode (hereinafter referred to as PD), 31 is a fiber, and specifically, is a highly water-absorbing and highly hygroscopic fiber such as an acrylate type or a polymer type.

  FIG. 2 is a humidity detection circuit diagram in the present embodiment.

  A one-chip microcomputer (hereinafter referred to as CPU) 809 outputs a signal from an analog output port (hereinafter referred to as AOUT) and controls the base current of the transistor 802 via the base resistor 801 to set the current of the LED 32 To do. Reference numeral 804 denotes a current limiting resistor, and 803 denotes an emitter resistor.

  The output of the PD 33 is amplified by the operational amplifier 808. This amplification factor is resistance 806 / resistance 807. The output of the operational amplifier 808 is read by the A / D port of the CPU 809 and the relative humidity is detected. However, in this configuration, it is necessary to calibrate due to variations in the LED 32 and peripheral circuits. In this method, AOUT of the CPU 809 is automatically adjusted so that the output voltage of the operational amplifier 808 is 4.5 V in a stable humidity (for example, 50%) environment at the time of shipment from the factory, and stored in a nonvolatile memory (not shown). This value is read out immediately after the power is turned on and output from AOUT.

  FIG. 3 is a graph showing detection characteristics when humidity is measured using the circuit of FIG.

  The output becomes a curve of 201, and the transmittance increases as the humidity increases. As a result, the cathode voltage of the PD 33 decreases, and the output of the operational amplifier 808 decreases.

  FIG. 4 is a configuration diagram of the humidity sensor 101 in the present embodiment.

  The fiber is fitted into a fiber holder 36 made of resin and combined with a photo interrupter 37.

  An example in which the humidity sensor described so far is applied to a laser printer will be described.

  FIG. 5 is a cross-sectional view of the monochrome laser printer.

  An image forming apparatus that visualizes an image stored in a memory by fixing a developer, that is, a toner, on a recording material such as print paper is represented by a laser beam printer or a copying machine, and is widely used due to its quietness. ing.

  In such an image forming apparatus, a printing operation is carried out by carrying a known electrophotographic technique, that is, an exposure, development, and transfer process, so that an image visualized with toner is carried on a recording material such as print paper. The process ends when the image is fixed on the recording material.

  53 is a paper cassette for paper P, 12 is a paper presence / absence detection lever for detecting the presence / absence of paper P, and 11 is a paper presence / absence detection sensor. The sheet presence / absence detection sensor 11 is a transmissive photo interrupter, and is configured such that when the sheet P is not in the sheet cassette 53, the sheet presence / absence detection lever 12 shields the detection unit of the sheet presence / absence detection sensor 11.

  Further, downstream of the paper supply roller 54, a feed roller 51 that conveys the paper P, a retard roller 52 that rotates in a direction to return the paper P to the paper cassette 53 when a plurality of paper P are supplied in an overlapping manner, A paper feed sensor (not shown) for detecting completion and a registration roller pair 55 for synchronous conveyance are provided, and a registration sensor 27 for detecting that the paper P has reached the registration roller pair 55 is provided.

  A process cartridge 21 that forms a toner image on the photosensitive drum 56 based on the laser beam from the laser scanner unit 18 is provided downstream of the registration roller pair 55. The toner image on the photosensitive drum 56 is transferred onto the paper P by the transfer roller 57. Further, a fixing device 6 that heat-presses and fixes a toner image formed on the paper P is provided downstream of the process cartridge 21, and a fixing paper discharge that detects passage of the paper P is provided downstream of the fixing device 6. A sensor 15 is provided. The paper P for which recording has been completed is stacked on a stacking tray (not shown) at the top of the machine.

  Reference numeral 14 denotes a conveyance roller for nipping and conveying the paper P.

  Further, the laser scanner unit 18 includes a laser unit 26 for emitting laser light, a polygon motor 25 for scanning the laser light from the laser unit 26 onto the photosensitive drum 56, an imaging lens group 19, a folding mirror 20, and the like. It is comprised by.

  The fixing device 6 includes a fixing roller 7, a heater 8 that heats the fixing roller 7, a pressure roller 9 that presses against the fixing roller 7, a temperature sensitive element 10 such as a thermistor, and the like.

  The process cartridge 21 includes a photosensitive drum 56, a pre-exposure lamp 22, a primary charger 23, a developing device 16, a cleaner blade 24, and the like that require a known electrophotographic process. Reference numeral 101 denotes a humidity sensor. It is necessary to dispose the humidity sensor 101 as far as possible from the fixing device 6. The reason is that moisture is released when the paper P passes through the fixing device 6 and the error becomes large. The LED is a type that emits an infrared wavelength strong against external light.

  The humidity sensor 101 is used to determine a bias value when transferring from the transfer roller to the paper P. For example, when the humidity is 20%, a transfer bias +3.0 kV is applied to the transfer roller. When the humidity is 80%, a transfer bias +1.0 kV is applied to the transfer roller. In the middle, linear interpolation is performed.

  In this embodiment, a monochrome laser printer is taken as an example. However, the present invention can also be applied to a color laser printer, and when applied to a color laser printer, the bias value for the intermediate transfer member can also be set to an optimum value. Furthermore, it goes without saying that the present invention can be applied to image forming apparatuses such as copying machines and FAX machines, and home appliances that need to detect humidity such as air conditioners.

(Second embodiment)
The description of the same part as in the first embodiment is given the same symbol and the description is omitted.

  FIG. 6 is a conceptual diagram illustrating this embodiment.

  34 is a first sheet in which the direction of the fibers is made into a mesh, and 35 is a second sheet in which the direction of the fibers is made into a mesh. In this example, the two sheets were stacked so that the fiber direction was 45 °. By using two sheets 34 and 35 in this way, the curve 202 in FIG. 3 is obtained, and the error can be detected small.

(Third embodiment)
The description of the same parts as those in the first and second embodiments will be given the same symbols, and the description thereof will be omitted.

  FIG. 7 is a perspective view of the humidity sensor configured on a substrate having other functions.

  Reference numeral 37 denotes a substrate. This substrate is not only the humidity detection circuit but also the control substrate of the monochrome laser printer described in the first embodiment. Part of it constitutes a humidity sensor. Thus, there is an advantage that the mounting process can be simplified by fixing the fiber 31 to the holder 36 and attaching the holder 36 later.

  The control method and the like may be as described in the first embodiment.

(Fourth embodiment)
The description of the same parts as those in the first to third embodiments will be given the same symbols, and the description thereof will be omitted.

  FIG. 8 is a circuit diagram of the fourth embodiment.

  Reference numeral 810 denotes a variable resistor (volume) for limiting the current of the LED 32. A unit 811 is used as a humidity sensor. Then, the output of the operational amplifier 808 is adjusted to 4.0 V under a single humidity (for example, 50%) environment. By so doing, variations in the humidity sensor unit can be suppressed.

  FIG. 9 is a perspective view of the present embodiment.

  By adjusting the unit in this way, it is not necessary to make adjustments at the factory of the product to be applied, for example, a dryer, a printer, an air conditioner, etc., and the process can be made inexpensive.

Explanatory drawing showing the basic configuration of the present invention Circuit diagram of the first embodiment Graph showing the detection characteristics of the first embodiment Sensor configuration diagram of the first embodiment Printer main cross-sectional view of the first embodiment Explanatory drawing showing the basic configuration of the second embodiment The perspective view of the board | substrate which showed the structure of 3rd Example. Circuit diagram of the fourth embodiment Sensor unit perspective view of the fourth embodiment Conventional sensor unit perspective view

Explanation of symbols

31 Fiber 32 Light emitting diode (LED)
33 Photodiode (PD)
36 Fiber holder 101 Humidity sensor 809 1-chip microcomputer (CPU)
811 Humidity sensor unit

Claims (8)

  A humidity detecting device, wherein a fiber whose thickness changes according to the ambient environmental humidity is arranged between the light emitting element and the light receiving element, and the humidity is detected by a change in the amount of transmitted light of the fiber. .   The fiber is a net-like first sheet knitted at a fixed angle and a second sheet knitted at an angle different from the fiber direction of the first sheet. The humidity detecting device according to claim 1.   The light-emitting element and the light-receiving element that are mounted on the substrate in advance are configured to be equipped with an integrated unit that incorporates fibers whose thickness changes according to the surrounding environmental humidity. Humidity detection device.   4. The humidity detecting device according to claim 1, wherein the light emitting element, the light receiving element, the fiber and the peripheral circuit are integrally formed on a substrate, and a resistance value of the peripheral circuit is adjusted.   The humidity detection apparatus according to claim 4, wherein the adjustment of the resistance value is a variable resistance.   The humidity detection apparatus according to claim 4, wherein the adjustment of the resistance value is a chip resistance.   The humidity detection apparatus according to claim 1, wherein the wavelength of the light emitting element is infrared.   An image forming apparatus comprising the humidity detection device according to claim 1.

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