JPH08179654A - Heating device - Google Patents

Abstract

PURPOSE: To suppress occurrence of surplus repairing expenses by cracking surely a plane substrate at a position to be cracked at the time of abnormal heating-up, stopping energizing, and preventing destruction of the secondary side parts after the plane substrate is cracked. CONSTITUTION: This heating device is provided with a heating member 1 consisting of a plane substrate having a wire heater on one side and a thermistor 9 and a DC contact 17 on the other side, a plastic stay 11 contacting with the heating member 11 at the same side with the thermistor and the DC contact, a temperature control circuit 19 receiving an output of the thermistor through the DC contact, varying supply quantity of electric power to the wire heater, and performing temperature control, and a temperature fuse 14 contacting with the thermistor being the heating member between the wire heater and the temperature control circuit at the same side, when the wire heater is abnormally heated, the plane substrate is cracked at a specific position by utilizing thermal transformation of the plane substrate, and the temperature fuse 14 is arranged at directly under its structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device such as a fixing device that heats toner transferred onto a sheet to fix it on the sheet.

[0002]

2. Description of the Related Art Conventionally, a heating device of this type has a heating member 1 shown in FIG. 2 and a plastic plate 11 which is a supporting member shown in FIG.
Are bonded together, and the thermal fuse 14 and the like are further attached, so that the structure is as shown in FIG.

In such a heating device, the linear heating element 2 (of the heating member 1) is generated by causing a short circuit failure of the triac 18 (see FIG. 5) in the temperature control circuit 19 which is the temperature control means. 2) when the temperature rises abnormally, the alumina substrate, which is a flat substrate, is deformed, the alumina substrate is cracked at the mechanically weakened 6-steel hole, and the power supply to the linear heating element 2 is stopped. This will ensure safety and
Even if the alumina substrate is cracked, the secondary side circuit including the part to which the primary voltage is applied, the thermistor 9 and the DC contact 17 and G
By providing a sufficient distance from the ND site, 1
The secondary voltage is prevented from sneaking into the secondary circuit or GND.

In FIG. 4, 13 is a thermistor hole, and in FIG. 5, 15 and 16 are AC contacts (a), (b), 17
Is a DC contact.

[0005]

However, in the above-described conventional heating device, as shown in FIG. 4, the thermal fuse mounting hole 12 for mounting the thermal fuse 14 is formed in the plastay 11 which is a supporting member. For,
There are parts with different heat dissipation states. In other words, since the heat capacity of air is larger than that of Plastay 11 and air,
Even if the linear heating element 2 is abnormally evenly heated due to poor heat dissipation in the thermal fuse mounting hole 12 part, the thermal fuse mounting hole 12
The part of the alumina substrate corresponding to the position
The temperature is higher than that of the part that is in close contact with. Therefore, the thermal deformation of the alumina substrate becomes larger in the thermal fuse mounting hole 12 portion than in other portions, and the alumina substrate in the thermal fuse mounting hole 12 portion is cracked before the mechanical hole 6 portion where the mechanical strength is lowered. There were cases. Even in this case, energization is stopped, so safety can be secured, but since the position where the crack is made and the position of the thermistor 9 and the like are close to each other, the part where the primary voltage is applied after the alumina substrate is cracked and the secondary side circuit
The distance from the ND site could not be secured sufficiently, and the secondary circuit was destroyed in some cases, resulting in extra repair costs.

The present invention has been made in view of the above problems, and an object of the present invention is to reliably break a flat substrate at a position where it should crack at the time of abnormal temperature rise and to stop the energization. Another object of the present invention is to provide a heating device which prevents unnecessary repair costs by preventing the secondary side parts from being destroyed after the crack.

[0007]

In order to achieve the above object, the present invention provides a heating member composed of a flat substrate having a linear heating element on one surface and both temperature detecting means and temperature detecting output transmitting means on the other surface. The linear heating element by receiving the output of the temperature detection means through the temperature detection output transmission means and a supporting member that is in contact with the heating member on the same surface side as the temperature detection means and the temperature detection output transmission means. Temperature control means for controlling the temperature by changing the power supply amount to the
A thermal fuse provided between the linear heating element and the temperature control means and in contact with the temperature detecting means of the heating member on the same surface, and thermal deformation of the planar substrate when the linear heating element abnormally generates heat. In the heating device having a structure in which the plane substrate is broken at a specific position by utilizing, the thermal fuse is arranged immediately below the structure in which the plane substrate is broken at a specific position.

[0008]

According to the present invention, since the thermal fuse is arranged immediately below the structure of the heating member which is broken at a specific position on the flat substrate, the flat substrate is surely broken at a position where it should be broken at the time of abnormal temperature rise and the energization is stopped. In addition to the above, it is possible to prevent the secondary side parts from being destroyed after the flat substrate is cracked, and to suppress the generation of extra repair costs.

[0009]

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

FIG. 1 is a block diagram of a heating apparatus according to the present invention, FIGS. 2 (a), (b) and (c) are top views, front views and bottom views of heating members, and FIGS. b) and (c) are a plan view, a front view, and a side view of the support member.

In FIG. 1, reference numeral 1 is a heating member, and as shown in detail in FIG.
It is arranged in the vicinity of the C through hole 5, and the steering hole 6
Together with the AC through hole 5 weaken the mechanical strength of the heating member 1.

Further, in FIG. 2, 9 is D on the heating member 1.
1 is a thermistor attached to the C pattern 10 by a conductive adhesive, and in FIG. 1, 14 is a thermal fuse for cutting off the conduction of AC when the heating member 1 has an abnormal temperature rise, and 15 and 16 are members (not shown). Contacts (a), (b) for conducting AC to the heating member 1 supported by
Reference numeral 7 is a DC contact for transmitting the output of the thermistor 9 to the temperature control circuit 19, 11 is a plastic support for supporting the heating member 1, and 18 is an ignition by the temperature control circuit 19 to change the power supplied to the heating member 1. It is a triac to let you.
The temperature control circuit 19 is for detecting the output of the thermistor 9 and controlling the firing angle of the triac 18 so as to keep the temperature of the heating member 1 constant.

Now, the structure of the heating member 1 will be described with reference to FIG. 2. Reference numeral 2 is a linear heating element that generates heat by an AC input, and 3 and 4 are for supplying electric power to the linear heating element 2 from the outside. AC electrodes (a), (b), 20 are AC electrodes (b) 4
And an AC pattern connecting the linear heating element 2 with a through hole connecting the AC electrode (b) 4 and the AC pattern 20,
7 is a DC electrode for connecting the output of the thermistor 9 to the temperature control circuit 19, and 8 is the DC pattern 10 and the DC.
It is a DC pattern that connects the electrode 7.

By the way, the plastay 11 is made of heat-resistant plastic, and details of the construction are shown in FIG.
That is, in FIG. 3, 12 is a thermal fuse mounting hole for mounting the thermal fuse 14 (see FIG. 1) so as to be in contact with the back side of the heating member 1, and 13 is the thermistor 9
The thermistor hole (see FIGS. 1 and 2) should be inserted.

In the heating device having the above construction, the temperature adjusting circuit 19 normally adjusts the firing angle of the triac 18 so as to keep the heating member 1 at a constant temperature according to the output of the thermistor 9. To do.

However, when the thermistor 9 comes off from the DC pattern 10 or the DC contact 17 comes off, the temperature control circuit 19 judges that the thermistor 9 detects that the temperature is extremely low and the triac. Maximum electric power is supplied to the linear heating element 2 via 18. Further, when the triac 18 has a short circuit failure, the control becomes impossible and the maximum electric power is supplied to the linear heating element 2, so that the secondary circuit may be destroyed.

However, in this embodiment, since there is a difference in heat capacity between the plastay 11 and the thermal fuse mounting hole 12, the thermal fuse mounting hole 12 is the hottest when the linear heating element 2 uniformly generates heat. As a result, the deformation also becomes large, and the steering hole 6 is surely cracked and AC energization is stopped.

Also, due to the half-wave failure of the triac 18,
When half of the maximum power is applied, the deformation of the substrate of the heating member 1 is slower than that of the full-wave failure. In such a case, the temperature of the thermal fuse part becomes the highest, so that before the chip is broken. The thermal fuse 14 is blown.

[0019]

As is apparent from the above description, according to the present invention, there is provided a heating member composed of a flat substrate having a linear heating element on one surface and both temperature detecting means and temperature detection output transmitting means on the other surface. The linear heating element by receiving the output of the temperature detection means through the temperature detection output transmission means and a supporting member that is in contact with the heating member on the same surface side as the temperature detection means and the temperature detection output transmission means. Temperature control means for controlling the temperature by changing the amount of electric power supplied to the heating element, and a temperature fuse provided between the linear heating element and the temperature control means and in contact with the temperature detection means of the heating member in the same plane. In a heating device having a structure in which the planar substrate is cracked at a specific position by utilizing thermal deformation of the planar substrate when the linear heating element abnormally heats, Since the above-mentioned thermal fuse is arranged in the above, the flat board is surely broken at a position where it should be broken at the time of abnormal temperature rise and the current is stopped, and the secondary side parts are prevented from being destroyed after the flat board is broken, and extra repair is performed. It is possible to obtain the effect that the cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a heating device according to the present invention.

2A, 2B, and 2C are a top view, a front view, and a bottom view of a heating member of a heating device according to the present invention.

3 (a), (b) and (c) are a plan view, a front view and a side view of a supporting member of a heating device according to the present invention.

4 (a), (b) and (c) are a plan view, a front view and a side view of a supporting member of a conventional heating device.

FIG. 5A is a plan view of a supporting member of a conventional heating device,
(B) is a block diagram of the same heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating member 2 Linear heating element 6 Steering hole 7 DC electrode (temperature detection output transmission means) 9 Thermistor (temperature detection means) 11 Plastay (supporting member) 13 Temperature fuse mounting hole 14 Temperature fuse 19 Temperature control circuit (temperature control means) )

Claims (1)

[Claims] 1. A heating member composed of a flat substrate having a linear heating element on one surface and a temperature detection means and a temperature detection output transmission means on the other surface, and the same surface as the temperature detection means and the temperature detection output transmission means. A temperature control for performing temperature control by changing the power supply amount to the linear heating element by receiving the output of the temperature detection means via the temperature detection output transmission means and a support member in contact with the heating member on the side. Means and
A thermal fuse provided between the linear heating element and the temperature control means and in contact with the temperature detecting means of the heating member on the same surface, and thermal deformation of the planar substrate when the linear heating element abnormally generates heat. A heating device having a structure in which the planar substrate is broken at a specific position by utilizing the above, wherein the thermal fuse is arranged immediately below the structure in which the planar substrate is cracked at a specific position.