KR970001597B1 - Heater using on heat sheet material - Google Patents

Abstract

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Description

Heater for heating sheet material

1 is a plan view of one embodiment of a heater of the present invention.

2 is an enlarged cross sectional view taken along the line II-II of FIG.

3 is a plan view of another embodiment of a heater of the present invention.

4 is a plan view of another embodiment of a heater of the present invention.

* Explanation of symbols for main parts of the drawings

H: Heater 1: Economy board

2: Smoke body 3: Electrode part

4: Protective glass coating 5: Power supply wiring

6: paper size detector 7: relay switch

[Background of invention]

1. Field of Invention

The present invention relates to a heater for heating a sheet material, and more particularly, the present invention relates to a heater for fixing a toner transferred onto a sheet in a photosensitive drum in an electrophotographic processor.

2. Conventional Technology

In a so-called electrophotographic processor, the toner transferred onto the sheet in the photosensitive drum is fixed by being heat fused by a heater. Such electrophotographic processors are widely applied to dry copiers, laser printers, LED printers, and printing parts of facsimile machines.

However, in order to reduce the size and weight of the fixing unit for the electrophotographic process, and to shorten the temperature rise time to the usable temperature, the heating element on the insulating substrate is replaced with a conventional heater having a halogen lamp inserted therein as the heating heater for fixing. The heater which arrange | positions to a strip | belt-shaped may be used. General examples of such heaters are known from the specification of US Pat. No. 5, 068, 517.

Such a heater can be obtained by a simple manufacturing process of forming a resistor formed by printing and firing on a band using silver and palladium faces on a ceramic insulating substrate, and is generally a thin phase. Moreover, since the temperature of the toner can be settled instantaneously after energizing between both ends of the resistor, the configuration of the fixing unit for the electrophotographic process can be reduced, reduced in weight, and the cost can be reduced almost after energizing. It has an advantage.

However, the fixing unit for such an electrophotographic process consumes considerable power to fix the toner being transferred onto the paper to be conveyed at a relatively high speed to the paper by reliable fusion. Therefore, in the case where a different sized paper can be used, the heating length of the heating heater is not always generated to a length suitable for the largest available size. It is preferable to change the width to fit the paper of this small size in terms of reducing the running cost of the electrophotographic processing apparatus.

For example, Japanese Unexamined Patent Application Publication No. 3-140257 discloses two types of heating heaters of the above-described type, in which, in addition to the electrodes at both ends of the band-shaped heating element, an intermediate electrode electrically conducting is provided at various places in the longitudinal direction of the heating element. It has been proposed to select an electrode so that the length of the heat generating portion with respect to the band-shaped heating element can be appropriately selected so that only the region corresponding to the width of the paper used is effectively generated.

However, in the configuration shown in Japanese Unexamined Patent Publication No. 3-140257, the electrode conducting to the middle portion of the band-like heating element must be made of gold, silver, or equivalent conductive metal, and furthermore, the electrode is a heating heater substrate in which terminals are formed. You will be dragged to the end.

In addition, since the intermediate electrode attracted by the predetermined length is a conductive metal, the intermediate electrode is excellent in thermal conductivity, and thus, in the intermediate electrode connection portion in the temperature distribution when heating the heating element field under the influence of heat transmitted and lost in the intermediate electrode. There exists a problem that the temperature nonuniformity in which temperature falls will arise.

This means that fixing nonuniformity occurs with respect to the long direction of the heating heater, and adversely affects the performance of the electrophotographic processing apparatus.

[Summary of invention]

It is therefore an object of the present invention to provide a heater for heating a sheet material configured to appropriately select an emission length without causing non-uniformity in the temperature distribution of the heat generating portion.

In order to achieve the above object, the heater of the present invention is configured as follows.

That is, the heater of the present invention is characterized in that a plurality of band-like heating elements having different lengths are independently disposed on an insulating substrate, and means for selectively energizing each of the band-like heating elements are provided.

Since the resistors of the lengths disposed on the insulated substrate are independent of each other, there is no adverse effect on the temperature distribution in the long direction of each resistor.

Therefore, when the heating heater of the present invention is used as a fixing heater for the toner fixing part for the electrophotographic process, for example, the heating element to be heated is selected and energized based on the detection information of the size (width) of the paper to be selectively used. You can make it work. This makes it possible to realize proper toner fixing with no fixing unevenness without using power unnecessarily.

As a result, it continues to enjoy the advantage that the fixing unit can be made smaller and lighter in the electrophotographic processing apparatus. Furthermore, the running cost can be drastically reduced while maintaining good electrophotographic quality without uneven fixing.

Other objects and features of the present invention will become apparent from the following detailed description with reference to the accompanying drawings.

[Description of Preferred Embodiment]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1, 3, and 4, in the heater H for heating the sheet material of the present invention, a plurality of planes having different lengths on the upper surface of the rectangular insulating substrate 1 in plan view. The band heating elements 2a, 2b and 2c are arranged in parallel.

In the example shown in FIG. 1, for example, it has two heat generating elements 2a and 2b having a width corresponding to a size of four sizes and a width of an A4 size, and the right end of these smoke bodies 2a and 2b is insulated. It is provided at the right end of the board | substrate 1.

The interlayer substrate 1 can be made of, for example, an alumina / ceramic plate. Each heating element 2a2b can be formed by printing on the insulating substrate 1 using silver palladium paste and firing the same. Moreover, ruthenium oxide may be used as a material of a heat generating body.

The electrode parts 3a and 3b are formed by printing and baking silver paste so that a part may overlap at both ends of each heat generating body 2a, 2b. Furthermore, the protective glass coating 4 is performed by covering each of the heat generating elements 2a and 2b and the electrode portions 3a and 3b overlapping at both ends thereof. A part of each electrode part 3a, 3b is exposed without being covered by the said protective glass coating 4, and this part is connected only to the power supply wiring 5 ... by suitable means of high temperature soft solder copper as a part. It is becoming.

When the heater H is used as a toner mounting heater of an electrophotographic processing apparatus having a paper feeding function of different size paper, the relay switch 7 energizes based on the paper size detector 6 as shown in FIG. The heating elements 2a and 2b to be heated can be configured to be switched.

For example, when B4 size paper is supplied, the relay switch 7 switches to the B4 side contact, and only the heating element 2a corresponding to the B4 size width is generated. When A4 size paper is supplied, the relay switch 7 switches to the A4 side connection so that only the heat generating element 2b corresponding to the A4 size width is generated.

As can be seen in FIG. 1, the heating elements 2a and 2b which selectively generate heat as described above are completely independent of each other and do not exist as any element that adversely affects the temperature distribution over the entire length. Therefore, even when all of the heating elements 2a and 2b are being heated, the temperature is lowered due to the electrode contacting the middle portion of the heating part as in the heating heater shown in Japanese Patent Laid-Open No. 3-140257. There can never be a temperature body nonuniformity at all. Therefore, in the heater of the present invention, only the length corresponding to the paper width can be generated, the running cost can be reduced by reducing the power consumption, and the fixing nonuniformity due to the temperature distribution unevenness is not generated. Fixing quality or electrophotographic process quality can be maintained.

In the above description, an example in which two heating elements 2a and 2b corresponding to two paper sizes are disposed on the insulating substrate 1 is described. For example, as shown in FIG. It goes without saying that three heating elements 2a, 2b, and 2c may be disposed so as to correspond to the three sizes of the size.

Moreover, in the example of FIG. 1 and FIG. 3, although the one end part of each heat generating element 2a, 2b, 2c is arrange | positioned, as shown in FIG. 4, the heat generating elements 2a, 2b which differ in each length are center-separated. You may arrange. These may be appropriately selected depending on the type of supply such as a copier, a printer, or a facsimile using an electrophotographic process.

As the electric circuit for switching the heating elements 2a, 2b, and 2c that should generate heat based on the sheet selection information, an appropriate switch can be used in addition to using the relay switch as described above.

The scope of the present invention is not limited to the above embodiments, but obvious changes and modifications within the scope of the principles described in the claims are all included within the scope of the present invention.

Claims (4)

A heater for contacting and heating a sheet material, which is a paper used in an electrophotographic process, comprising: an insulating substrate; A plurality of band-like fumes formed independently of each other on the insulating substrate and having different lengths; And means for selectively energizing one of the band-like heating elements, wherein the selectively energizing means selects a band-like heating element to be energized based on detection information of a paper size. The heater according to claim 1, wherein said paper is supported on a heat resistant film. The heater according to claim 1, wherein said band-like heating element is formed by printing and firing a silver-palladium paste. The heater according to claim 1, wherein said band-like heating element is formed by printing and baking ruthenium oxide paste.