JPH0820817B2 - Fixing device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a heating fixing device such as a copying machine, and more particularly to a fixing device having an improved temperature control unit of a heating roller fixing device.

[Prior art]

Generally, a heating roller fixing device is composed of a heating roller and a pressure roller that is driven to rotate in contact with the heating roller, and various measures have been taken in order to obtain a preferable fixing state. The heating roller facilitates the separation of the transfer material from the roller after fixing by applying a hard Teflon coating on the surface of a roll core in which a heating means such as a heater lamp is installed. In the pressure roller, the surface of the roll core in which the heating means is not provided is covered with a layer of a releasable material such as PFA tube or silicone rubber. The pressure roller is pressed against the heating roller, and the pressure roller is driven to rotate by driving the heating roller with a drive source such as a motor. In such a fixing device, in order to obtain a preferable fixing temperature, a temperature sensor for detecting the surface temperature of the heating roller and a temperature control board for controlling the surface temperature of the heating roller by energizing the heater based on the signal of the detected temperature sensor. And temperature control means constituted by The temperature control board in the temperature control means is conventionally provided on the body side of the copying machine in the vicinity of the fixing device, and exchange of a signal from the temperature sensor or supply of power to the heater via the temperature control board is performed on the side wall of the fixing device. Electrical connection was achieved by a connector that was interposed between the side wall of the main body of the copying machine and the side wall opposite to this.

[Problems to be Solved by the Invention]

As the cord from the temperature sensor to the temperature control board, a chromel-alumel wire or a copper-constantan wire, which is stronger than a normal cord at higher temperatures, is used. Moreover, the signal current flowing through the code is extremely small and is only a few μA (microamperes) at most. In a conventional method in which a connector is interposed in the middle of the cord due to the material of the conductive portion of the cord in which such a minute signal current flows, there is a risk that contact failure may occur in the connector portion. It was accompanied by sex. If a contact failure occurs in this connector section, the fixing temperature control cannot be performed accurately, and defects such as image quality failure (fixing under) and copy operation failure (no warm-up) appear. The present invention has been made in view of the above-mentioned drawbacks of the prior art, and by providing a temperature control board on the fixing device side, it is possible to stop the interposition of a connector between the temperature sensor and the temperature control board and to send a minute signal current. An object of the present invention is to provide a fixing device which prevents occurrence of fixing failure due to imperfect contact by directly connecting a flowable cord to a temperature control board.

[Means for solving problems]

The above object is to provide a unit in which a heating roller having a built-in heater and a pressure roller that is in pressure contact with the heating roller are rotatably supported, and a temperature sensor is arranged on the surface of the heating roller by means of a guide member. In a fixing device that can be pulled out from the main body, a temperature sensor arranged on the surface of the heating roller and a temperature control board arranged at a lower position apart from the heating roller are connected by a heat resistant signal code, and this temperature control board Is provided in the unit.

【Example】

An embodiment of the fixing device according to the present invention will be described below with reference to FIGS. 1 to 4, but the embodiment of the present invention is not limited thereto. FIG. 4 is a block diagram of a copying machine including the fixing device of the present invention. First, each process up to the fixing device in the copying machine will be described. The image carrier 10 is a drum-shaped photoconductor in which a photoconductive substance is laminated on a conductive metal substrate to have a certain thickness, and is rotatably configured to rotate in a certain direction so that its photoconductive surface is plural. It goes through the processing stations in sequence. The image carrier 10 is charged by the charger 11 so that the surface of the image carrier 10 uniformly holds electric charges. The image carrier 10 whose photoconductive surface is uniformly charged rotates to enter the exposure unit 20. In the exposure section 20, the reflected light from the document is applied to the photoconductive surface of the image carrier 10 through an optical system such as a mirror and a lens, and the charge of the exposed part is discharged to form an electrostatic latent image of the document on the part. . The image carrier 10 on which the electrostatic latent image is formed rotates and enters the developing unit 30. In the developing section 30, the electrostatic latent image is developed by a developing device 31, and a developing material containing charged toner particles is attached to the latent image to visualize the original image of a document. The image carrier 10 carrying the toner image visualized by the toner rotates and enters the transfer unit 40. In the transfer section 40, the recording paper is conveyed in synchronization with the toner image, and the toner image is transferred onto the recording paper. The recording paper on which the toner image is transferred is separated from the image carrier 10 by a separator 41 as a transfer paper, further fixed by a fixing device 50 according to the present invention, and ejected outside the machine. The discharged recording paper is taken up by a sorter 70 having guide means at the discharge port of the copying machine, and page alignment is performed. On the other hand, the image carrier 10 separated from the recording paper by the separator 41 enters the cleaning device 60 while carrying the untransferred residual toner, where the residual toner on the image carrier is removed and a new copy cycle is entered. Be prepared to do so. FIG. 1 is a sectional view of a fixing device according to the present invention. The fixing device 50 includes a heating roller 52 having a heating means 51 therein and a pressure roller not having a heating means in contact with the heating roller 52.
53 and a temperature sensor 54 for detecting the surface temperature of the heating roller 52
And a temperature control board 55 for controlling the surface temperature of the heating roller 52 based on a signal detected by the temperature sensor 54. Further, guide members 501 are provided on both outer sides of the fixing device so that the fixing device can be pulled out from the copying machine as a unit. The heating roller 52 has an outer diameter of 30 mm, a wall thickness of 2 mm, and a length.
It has a structure in which a 900 watt lamp heater as a heating means is internally provided in a 270 mm metal cylinder, and its surface is coated with hard Teflon. The pressure roller 53 has an outer shape of 30 mm and a length of 27 mm including a thickness of 5 mm of a coating material having a releasing property such as silicon rubber.
It is formed into a cylindrical body of 0 mm and is configured to be pressed against the heating roller 51 and driven to rotate. The guide member 501 includes a moving guide plate 503 and a fixed guide plate 502.
And a middle guide plate 504 and a set of four rows of balls 505. The moving guide plate 503 is fixed to the notches of both the frames 512 and 513 of the fixing device, and the copying machine main body side is shown by a chain line. A fixed guide plate 502 is attached and fixed to the frames 506 and 507, and an intermediate guide plate 504 is interposed between the fixed guide plate 502 and the moving guide plate 503 via a set of four rows of balls 505.
If the length of the guide plate is set to be the front and rear length of the fixing device (perpendicular to the paper surface) or longer, the fixing device can be sufficiently pulled out of the copying machine main body when necessary. Then, the fixed guide plate 502, the movement guide plate 503, and the intermediate guide plate.
Reference numeral 504 denotes a trough-shaped member each having a predetermined length in a direction perpendicular to the plane of the paper, and each side end portion is formed in a hemispherical shape, and the fixed guide plate 502 to the moving guide plate 503 are intermediate guides. A plurality of four ball rows are fitted to each other via a plate 504. FIG. 2 is a layout view of the temperature control unit of the fixing device of the present invention, and FIG. 3 is a layout view of the temperature control unit of the conventional fixing device. The temperature control unit includes a temperature sensor 54 for detecting the surface temperature of the heating roller 52, a heating means 51 by a lamp heater for increasing the temperature of the heating roller 52, and a signal from the temperature sensor for energizing the lamp heater of the heating means 51. A temperature control board 55 for controlling the surface temperature of the heating roller 52, a signal code 57 for sending a detection signal current from a temperature sensor 54 to the temperature control board 55, and a heating means.
A heater cord 58 for energizing 51 and a connector 510 are provided on the side wall of the copying machine body side facing the side wall of the fixing device. The temperature sensor 54 is a semiconductor type normally used temperature sensor capable of changing a resistance value by its own temperature change and replacing the change in resistance value with a change in current value. The heating roller 52 is raised to about 200 ° C., and at the time of fixing, the fixing temperature is strictly controlled in order to melt the toner and sufficiently bring it into close contact with the recording paper. As described above, the signal code 57 is brought close to the heating roller 52 at least in a portion where it is connected to the temperature sensor 54, and therefore the temperature rises to around 200 ° C., so that the chromel material can withstand a high temperature.・
Alumel wire or copper-constantan wire is used.
A detection signal current from the temperature sensor 54 flows through the signal code 57, but the current value is several μA at maximum even if it includes fluctuations.
It is a very small current of only (microamps). The temperature control board 55 inputs a fixing control signal from the copying machine main body side, a heater energizing current, an element operating power supply current for the temperature control board, a detection signal current of the temperature sensor 54, etc., and the heating means 51. The controlled heater energization current is output to the heater. In the fixing device 50, the connector 510 is provided on the front side in a direction perpendicular to the paper surface in FIG. 1 by the guide member 501 shown in FIG.
In FIG. 2, the connector unit 510 is constructed so that it can be pulled out from the main body of the copying machine in the direction of the arrow (to the right).
Is an electrical connection portion for transmitting a signal current or a power supply current from the main body of the copying machine to the temperature control board 55. As shown in the layout diagram of the temperature controller of the fixing device of the present invention in FIG. 2, the temperature sensor 54 and the temperature control board 55.
And are provided on the side of the fixing device that can be pulled out from the main body of the copying machine. This means that the connector does not intervene in the signal current loop from the temperature sensor 54 to the temperature control board 55, and the detection signal current from the temperature sensor 54 remains as it is.
Temperature is accurately transmitted. On the other hand, as can be seen from FIG. 3 showing the layout of the temperature controller of the conventional fixing device, the temperature sensor 54, the temperature control board 55, the connector 510, which constitute the temperature controller,
Although the same applies to the components such as the signal code 57 from the temperature sensor 54 and the heater code 58, the temperature control board 55 is not included in the configuration in the fixing device indicated by the alternate long and short dash line. Therefore, the signal code 57 for transmitting the detection signal current from the temperature sensor 54 is connected to the connector 510 on the way to the temperature control board 55.
There is no choice but to intervene. This signal code 57 uses a chromel-alumel wire or a copper-constantan wire made of a material that can withstand high temperatures for the same reason as described above, and the reason why the current value flowing through the signal code 57 is very small. If the connector is interposed in the middle of the connection, a signal current may not be accurately transmitted to the temperature control board 55. This is often due to the contact resistance generated in the connector section, and the current flowing through the signal code is very small. Therefore, even if the resistance value fluctuates slightly, it should be transmitted to the temperature control board 55. This occurs because the value of the true detection signal current deviates. As shown in FIG. 2, as a result of configuring the temperature controller of the fixing device, a connector 510 provided on a side wall 511 of the copying machine body facing the fixing device has a fixing control signal current from the copying machine body side. (Several mA), heater power supply current (DC1k
VA), a power supply current for operating the electronic element of the temperature control board 55 (DC 5V, several mA), and the like. No connector is provided in the middle of the closed loop of the signal current formed by the temperature sensor 54 and the temperature control board 55. Therefore, the connector is constructed by removing the part related to the signal current from the temperature sensor, which is greatly affected by the slight change in the contact resistance value, and eliminates the temperature control failure caused by this connector part in the past. I was able to do it.

【The invention's effect】

As is apparent from the above description, in the fixing device of the present invention, the temperature control board is incorporated in the fixing device so that the connector does not intervene in the middle of the signal code for flowing the minute detection signal current from the temperature sensor in the temperature control part. Therefore, the detection signal current from the temperature sensor can be accurately transmitted to the temperature control board, and since this temperature control board is arranged via the signal code apart from the fixing heating part, this temperature is increased by the heating high temperature. Therefore, the fixing device is provided, which does not damage the control substrate, and as a result has a remarkable effect in reducing the fixing failure.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a fixing device of the present invention, FIG. 2 is a layout view of a temperature control unit of the fixing device, FIG. 3 is a layout view of a temperature control unit of a conventional fixing device, and FIG. The figure is a block diagram of a copying machine including the fixing device of the present invention. 10 ... Image carrier, 20 ... Exposure section 30 ... Developing section, 40 ... Transfer section 50 ... Fixing device, 51 ... Heating means 52 ... Heating roller, 53 ... Pressure roller 54 ... Temperature sensor 55 ... Temperature control board 57 ... Signal Code, 58 ... Heater code 501 ... Guide member, 510 ... Connector 511 ... Copy machine side wall 60 ... Cleaning device 70 ... Sorter device

Continuation of front page (56) Reference JP-A-57-20628 (JP, A) JP-A-55-135879 (JP, A) JP-A 57-189169 (JP, A) JP-A 60-63563 (JP , A) JP 56-113178 (JP, A) JP 57-196330 (JP, A) JP 56-1065 (JP, A) Actual development 62-41166 (JP, U) Actual development 58-11744 (JP, U) Actually open 60-59280 (JP, U) Actually open 55-97763 (JP, U) Actually open 58-121040 (JP, U) Actually public 61-24993 (JP, Y2)

Claims (1)

[Claims] 1. A heating roller having a built-in heater and a pressure roller press-contacting the heating roller are rotatably supported.
In a fixing device in which a unit having a temperature sensor on the surface of the heating roller can be pulled out from the main body of the copying machine by a guide member, a temperature sensor arranged on the surface of the heating roller and a position lower than the heating roller are arranged. A fixing device characterized in that the temperature control board is connected to the temperature control board by a heat resistant signal code, and the temperature control board is arranged in the unit.