JPH03201385A - Heating element and manufacture thereof - Google Patents

Abstract

PURPOSE:To simplify the structure and reduce the manufacturing cost of a heating element and allow the heating element to evenly generate heat by forming an electric heating film on the outer or inner surface of a tubular drum pipe. CONSTITUTION:An electric heating film 4 is formed via an insulating layer 3 on the inner surface of a tubular drum pipe 2 having a photosensitive layer 1 formed on the outer surface thereof. The electric heating film 4 is formed by application and drying of an electric heating paint and has a pair of circular electrodes 5 provided at both ends thereof, and when a voltage is applied between both electrodes the electric heating film 4 generates heat so that the photosensitive layer 1 provided on the surface of the tubular drum tube 2 is evenly and uniformly heated. The structure of a heating element is thereby simplified and unevenness in heat generation is prevented at low cost.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a heating element suitable for use in photoreceptor drums, fixing rollers, etc. used in image forming apparatuses such as electrostatic copying machines and laser beam printers, and the like. This relates to a manufacturing method.

<Prior art> In image forming apparatuses such as electrostatic copying machines and racer beam printers that utilize the so-called Carlson process, a photoreceptor drum is formed by forming a photoreceptor layer on the outer surface of a conductive cylindrical drum tube. It is used.

Since the charging characteristics of the photosensitive layer of the photosensitive drum change depending on the temperature, a heater is placed inside the cylindrical drum tube so as not to be affected by changes in temperature. The photosensitive layer is kept at a constant temperature at all times.

As the above-mentioned heater, a cylindrically rounded sheet heater fitted into the cylindrical drum material tube, a tubular heat generating lamp placed at the rotation center of the cylindrical drum material tube, etc. are used. .

<Problems to be Solved by the Invention> When using the above-mentioned cylindrical rolled sheet heater, among the photosensitive layers formed on the outer surface of the cylindrical drum tube,
Since the portion corresponding to the portion (gap portion) where the edges of the planar heater face each other is not sufficiently heated, temperature unevenness occurs, which has the drawback of causing unevenness in the photosensitive characteristics of the photoreceptor drum.

Therefore, it is possible to arrange the sheet heater and the cylindrical tube so that they can rotate relative to each other to equalize the heating, or use a sheet heater with slanted edges to fill the gap in a spiral shape. This arrangement prevents heating unevenness from concentrating near one generatrix on the circumference, thereby reducing unevenness in photosensitive characteristics.

However, in the former case, the structure is complicated, and centering the base tube and heater during assembly or heater replacement is not easy compared to when both are fixed, and the parts There is a problem in that the center axes of the two become misaligned due to wear or the like, which tends to cause uneven heating.

On the other hand, in the latter case, the unevenness in photosensitive characteristics caused by uneven heating can be reduced to the extent that it is not noticeable in normally formed images, but heating unevenness still exists, so depending on the type of image to be formed, the image may be heated There is a problem of being affected by unevenness. Further, as mentioned above, a specially shaped planar heater with oblique edges is required for the gap portion, which increases the cost.

Further, when a heat generating lamp is used, there is a problem in that the heat generating lamp has delicate parts such as filaments and has a significantly shorter lifespan than the above-mentioned planar heater, so that it must be replaced frequently.

Therefore, a photoreceptor drum has been proposed in which a cylindrical heating element, in which a heater wire such as a nichrome wire is embedded, is inserted into a cylindrical drum body tube made of an insulating material such as insulating ceramics. (Japanese Unexamined Patent Publication No. 56-13585
Publication No. 5).

According to the heating element having the above configuration, when the heater wire is energized from the pair of annular electrodes to generate heat, the entire cylindrical body is heated almost uniformly, so that the photosensitive characteristics of the photosensitive layer on the surface of the cylindrical drum material tube are affected. It is possible to prevent unevenness from occurring. However, this heating element takes a long time after the heater wire is energized until the entire cylinder is evenly heated, so it takes a long time to heat the photoreceptor drum to a predetermined temperature after the power is turned on. There is a problem that it takes

In addition, a heating medium such as alcohol is sealed inside the cylindrical drum tube, and the heat from the heater is equalized by the vapor of the heating medium that fills the inside of the drum tube before being transmitted to the tube. A photosensitive drum has also been proposed (Japanese Patent Laid-Open No. 1983
(Japanese Patent No. 48062) However, the heating element having the above structure has the following problems. (1) In order to maintain the airtightness of the cylindrical drum tube, the structure of the cylindrical drum tube becomes complicated.

(2) If the airtightness of the cylindrical drum tube is not sufficient, the heat medium will leak and the thermal conductivity from the heater to the cylindrical drum tube will change, making maintenance time-consuming.

The present invention has been made to solve the above-mentioned problems, and provides a heating element that has a simple configuration, low manufacturing cost, and can generate heat uniformly, and a method for manufacturing this heating element. The purpose is to

Means for Solving the Problems> In order to solve the above problems, the heating element of the present invention is characterized in that an electrically heated coating film is formed on the outer surface or inner surface of the cylindrical drum tube.

In addition, after applying the photosensitive layer coating liquid to the inside and outside of the cylindrical drum tube by dip coating, an electrically conductive exothermic paint discharge port with a length that spans almost the entire axial length of the cylindrical drum tube is installed inside the cylindrical drum tube. Insert the energized exothermic paint film supplying body with the cylindrical drum tube, and while rotating the cylindrical drum tube, the energized exothermic paint is cast from the discharge port, and is dried to form a photosensitive layer on the back surface of the cylindrical drum tube. It is characterized in that it is interposed to form an electrically heated coating film.

Effects> The heating element of the present invention having the above structure forms an electrically heated heat-generating coating film on the outer or inner surface of the cylindrical drum material tube, so that uniform heating can be achieved without temperature unevenness.

In addition, according to the method for manufacturing the heating element having the above structure, since the photosensitive layer acts as an insulating layer when no light is irradiated, the cylindrical drum tube is dipped into the photosensitive layer coating solution and pulled up, so-called dip coating. By forming a photosensitive layer on the inside and outside of the cylindrical drum material tube by a process, it is possible to form a photosensitive layer on the outside and at the same time form an insulating layer on the inside. There is no need to newly form an insulating layer interposed between the shaped drum material tube and the electrically heated coating film, and the manufacturing process can be simplified.

Furthermore, since the coating is carried out by casting without rotating the cylindrical drum stock tube, it is suitable for forming an electrically heated coating film on the inner surface of the cylindrical drum stock tube. Moreover, a coating film can be easily formed.

<Example> The present invention will be explained below with reference to the drawings.

First, the embodiment shown in FIG. 1 will be described.

FIG. 1 shows a photosensitive drum using the heating element of the present invention. In the photosensitive drum shown in the figure, an electrically conductive heat-generating coating film 4 is formed on the inner surface of a cylindrical drum tube 2 having a photosensitive layer 1 formed on its outer surface, with an insulating layer 3 interposed therebetween.

The cylindrical drum tube 2 is entirely made of a conductive material such as aluminum.

The photosensitive layer 1 formed on the surface of the cylindrical drum tube 2 is formed by applying a photosensitive layer coating liquid and drying it.

The energizing heat generating coating film 4 is formed by applying an energizing heat generating paint and drying it.

A pair of annular electrodes 5 are provided at both ends of the electrically conductive heat-generating coating film 4, and when a voltage is applied between both electrodes, the electrically conductive heat-generating coating film 4 generates heat, and the photosensitive layer on the surface of the cylindrical drum tube 2 is heated. 1 can be heated evenly and evenly.

Note that it is desirable that the area of the photosensitive layer 1 formed on the outer surface of the cylindrical drum tube 2 to be used as an image forming area remains within the range shown by the following formula (1).

R>r+3 (unit: m m ) (1) In formula (1), R and r represent half the width of the electrically exothermic coating area and half the width of the image area, as shown in FIG.

As the electric heating paint, for example, the trade name "MRX-001J" manufactured by Rasmol Kagaku ■ is commercially available. This paint is composed of a combination of several kinds of heat generating agents and inorganic substances, with an organic substance as a matrix. Organic solvents, e.g.
It dissolves in xylene or Kijiroru, etc., and dries naturally in about 20 minutes at 20℃ after application (at room temperature).Since it is in the form of a paint, it can be applied to any shape of object, and it can be used in heating ranges. It can be set from 1 to 1000°C.

When the above-mentioned energizing heat-generating paint is used as a energizing heat-generating coating, the energizing heat-generating paint has self-adhesive properties at room temperature, so the electrodes can be formed by simply pasting silver paste, copper tape, copper mesh tape, etc. Furthermore, it can be used for both alternating current and direct current. Further, since the energized heat-generating paint dries naturally at room temperature, a drying step is not necessary, and the photoreceptor drum can be easily formed.

The heat generation temperature of the current heat generation coating film made of the above current heat generation paint is determined by the grade of the current heat generation paint, and one having a desired heat generation temperature can be selected.

Furthermore, the film thickness of the electrically heat-generating coating film is only related to its temperature increase rate, and has no relation to the heat generation temperature.

Therefore, it is not necessary to be strictly particular about the amount of the electrically heat-generating coating film applied, but the following values are preferable for the photosensitive drum.

Fever temperature: 30-60℃ application
Amount: 150-250g/m2 Drum applied voltage: 2
The insulating layer 3 interposed between the current-carrying heat-generating coating 4 and the cylindrical drum tube 2 prevents the voltage applied between the electrodes provided at both ends of the current-carrying heat-generating coating 4 from leaking. It is necessary to prevent this from occurring, and it is desirable that it be insulating.

Further, the insulating layer fills the space between the electrically conductive heat-generating coating film 4 and the cylindrical drum tube 2 without leaving a gap, and functions to equalize heat conduction.

Note that if the volume resistivity of the coating film of the photosensitive layer coating liquid used to form the photosensitive layer 1 is 10 Ω cm or more, this photosensitive layer coating liquid can also be used for the insulating layer 3. . Therefore, according to the method of manufacturing a heating element of the present invention, since the photosensitive layer coating liquid can be used as the photosensitive layer 1 and the insulating layer 3, as shown in FIG. The photosensitive layer 1 and the insulating layer 3 can be formed at the same time by dipping the photoreceptor into a paint and pulling it up, which is called dip coating, thereby simplifying the manufacturing process.

3 to 5 show a method of forming a heating element on the inner surface of a cylindrical drum tube.

FIG. 3 shows a state in which the electrically conductive heat-generating coating film supply body 10 is inserted into the inside of the cylindrical drum tube 2, and FIG.
+b) shows a side view and a front view of the electrically heated coating film supply body 10.

The supply path 10a of the energized exothermic coating film supply body 10 is supported by a support member 11 on the rotationally driven side that rotates in synchronization with the rotation of the cylindrical drum tube 2, and both ends of the cylindrical drum tube 2 are connected to each other. A lid-like member 12 and 13 is fitted to rotatably support the cylindrical drum tube 2 and prevent the energized heat-generating paint from leaking out of the cylindrical drum tube 2. .

Reference numeral 14 denotes a rotation shaft on the rotation drive side for rotating the cylindrical drum tube 2. At this time, the energized heat-generating coating film supply body 10 is not synchronized with the rotation of the cylindrical drum tube 2 and is fixed.

As shown in FIG. 4 (al, mountain), the energizing exothermic coating film supply body 10 includes a supply path 10a to which a coating liquid for forming an energizing exothermic coating film is supplied, and a supply path 10a that branches from this and is connected to a supply path 10a. It consists of a large number of discharge passages 10b arranged in the longitudinal direction of the supply passage 10a, which discharge the coating liquid supplied in a small diameter, and discharge ports 10c which discharge the coating liquid divided into small quantities.The discharge passage 10b faces downward. It is.

A method for forming an electrically exothermic coating film on the back surface of the cylindrical drum tube 2 using this electrically exothermic coating film supplier 10 will be described with reference to FIG.

The electrically conductive exothermic coating film supplier 10 inserted into the cylindrical drum tube 2 has a discharge port 10c located near the wall surface 2a inside the cylindrical drum tube 2.

Since the electrically conductive exothermic coating film supply body 10 is fixed so as not to rotate, when the cylindrical drum base tube is rotated in one direction while discharging the coating liquid from the discharge port 10c, the cylindrical drum base tube wall surface 2a The coating liquid 21 is deposited on top, and an electrically heated coating film is formed.

The electrically heated coating film formed by the above manufacturing method is
Since the electrically conductive exothermic coating film supply body 10 evenly distributes the coating liquid supplied through the supply channels 1 and 0a through the plurality of discharge channels 10b, the film thickness becomes uniform.

Furthermore, as shown in FIG. 5, if the blade 20 is arranged downstream of the discharge port 10C with respect to the rotational direction of the cylindrical drum tube, the blade 20 and the wall surface of the cylindrical drum tube can be
By adjusting the distance between a and a, it is possible to form an electrically heated coating film having a desired uniform thickness. Note that instead of the blade 20, for example, a brush or the like may be used.

Further, it is preferable that the region width of the electrically heat-generating coating film be formed within the range shown by the above-mentioned formula (1).

In addition, in the method for manufacturing a heating element of the present invention, a photosensitive layer coating liquid is applied to the inside and outside of the cylindrical drum tube by dip coating, thereby forming a photosensitive layer on the outside of the cylindrical drum tube. At the same time as forming, an insulating layer was also formed inside.
The present invention is not limited to this, and it is also possible to form the photosensitive layer and the insulating layer separately.

In this case, in order to form an insulating layer inside the cylindrical drum tube, for example, the above-mentioned method of forming an electrically exothermic coating film may be used. rMRX-003" is used.

Furthermore, when a temperature control circuit or the like is installed inside the cylindrical drum tube, there is a risk of voltage leakage if the temperature control circuit etc. comes into direct contact with the current-carrying heat-generating coating film, so if necessary, the current-carrying heat-generating It is preferable to form an insulating layer on the surface of the adhesive coating.

In order to form an insulating layer on an electrically conductive heat-generating coating film, even if it is covered with an insulating film, an insulating paint such as rMRX-004J manufactured by Lastle Chemical Co., Ltd. is used to form the above-mentioned electrically conductive heat-generating coating film. It may be formed using a method.

Note that the heating element of the present invention is not limited to the photosensitive drum of the above embodiment, but can be applied to, for example, a fixing roller of an image forming apparatus. In this case, the fixing roller may be formed by forming an energized heat-generating coating film on the outer surface of the cylindrical drum tube, and then wrapping a fluororesin tape or the like over the energized heat-generating coating film.

In addition, various design changes can be made without changing the gist of the invention, and the invention can be used for various purposes.

<Effects of the Invention> The heating element of the present invention is constructed as described above, and since the current-carrying heat-generating coating itself generates heat at a constant temperature, it has a simple structure, is easy to manufacture, and is low-cost. Become.

Further, according to the method for manufacturing a heating element of the present invention, a uniform heating element without uneven heating can be manufactured more easily and at low cost.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the heating element of the present invention, and FIG. 2 is a method for manufacturing the photosensitive layer and the insulating layer when the same photosensitive layer and insulating layer are used together. FIG. 3 is a cross-sectional view showing an example of the method for manufacturing a heating element of the present invention, and FIG. 4 (al. A side view and a front view of an example of the coating film supply body, and FIG. 5 are cross-sectional views for explaining an embodiment of the method for manufacturing a heating element of the present invention. 4.-Electrical heat generating coating film , 10... Electrifying exothermic coating film supply 10a... Supply path, supply body, 10b... Discharge path, 10c... Discharge port. 527 1... Photosensitive layer 2... Cylindrical drum element Body 3...Insulating layer 4...Electric heat generating paint 5...Electrode 2...Cylindrical drum body 10-...Electrifying heat generating!!!Membrane donor membrane supply body a...Supply Path 10b...Discharge path 10c...Discharge port 10, a

Claims (1)

[Scope of Claims] 1. A heating element characterized by having an electrically conductive heating coating film formed on the outer or inner surface of a cylindrical drum tube. 2. The heat generating element according to claim 1, wherein the electrically conductive heat generating coating film is formed on the back surface of the cylindrical drum tube with an insulating layer interposed therebetween. 3. The heat generating element according to claim 1, wherein electrodes are attached to both ends of the electrically conductive heat generating coating film. 4. The heat-generating element according to claim 1, wherein the electrically conductive heat-generating coating is formed on the inner surface of the cylindrical drum tube via an insulating layer, and a photosensitive layer is formed on the outer surface to constitute a photosensitive drum. 5. The heating element according to claim 2 or 4, wherein the insulating layer is a photosensitive layer having a volume resistivity of 10^9 Ω·cm or more. 6. The heat generating element according to claim 1, wherein an insulating layer is formed on the surface of the electrically conductive heat generating coating formed on the outer surface of the cylindrical drum tube. 7. After coating the photosensitive layer coating liquid on the inside and outside of the cylindrical drum tube by dip coating, an electrically conductive exothermic paint discharge port is provided inside the cylindrical drum tube with a length that spans almost the entire length of the cylindrical drum tube. Insert the current-carrying heat-generating coating film supplying body having a cylindrical drum stock tube, and while rotating the cylindrical drum stock tube, the current-carrying heat-generating paint is cast from the discharge port, and is dried to form a photosensitive layer on the back surface of the cylindrical drum stock tube. 1. A method for producing a heat generating element, which comprises forming an electrically conductive heat generating coating film by interposing the above.