JPH02134672A - Drum heater - Google Patents

Abstract

PURPOSE:To eliminate the necessity of electrical means such as a heater and a control circuit for maintaining a prescribed temperature by taking advantage of frictional heat due to the rotation of a photosensitive drum. CONSTITUTION:In the photosensitive drum 2, a press spring 5 is fitted to a spring fixing member 12a equipped with a supporting axis 1, and a frictional member 4 as a frictional means is fitted to the other end so that the member 4 can come into contact with the side of a drum tube 3 due to the extension of the press spring 5. A shape memory alloy spring 6 as a shape memory means is fitted to a spring fixing member 12b provided on the supporting axis 1. Consequently, the photosensitive drum 2 is wormed by heat generated by the friction between the inner surface of the photosensitive drum 2 and the frictional means 4. When the photosensitive drum 2 reaches the prescribed temperature, the shape memory means 6 contracts and a gap created between the inner surface of the photosensitive drum 2 and the frictional means 4 prevents friction. Thus, the photosensitive drum 2 can be maintained at the prescribed temperature without using electricity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum heater device. More specifically, the present invention relates to a drum heater device provided in a photosensitive drum of an image forming apparatus such as an electronic copying machine or a printer.

Conventional Conventions and Distortions For example, a photoreceptor drum of an electronic copying machine, especially a photoreceptor drum having an arsenic-based photoreceptor, is usually provided with a heater for warming the photoreceptor drum so as to be in contact with the inner surface of the drum tube. It is being In order to supply power to the heater in the photoreceptor drum, which is a rotating body, a power supply means that connects the outside and the outside of the photoreceptor drum is required between an external power source and the photoreceptor drum. Conventionally, as this power supply means, a contact point such as a trunk ring is provided on the side of the photoreceptor drum, and a terminal having a sliding member such as a brush that is connected to a power source is provided to the contact point. .

FIG. 6 is a schematic diagram showing a longitudinal section of a conventional example of such a drum heater device.

The photosensitive drum (2) includes a drum tube (3) and drum flanges (3) attached to both ends of the drum tube (3).
7), a heater (20) provided so as to be in contact with the inner surface of the drum tube (3), and the drum tube (3)
It consists of a control circuit (21) provided inside. As the heater (20), for example, a commonly used film heater or a linear heater arranged on a stainless steel plate and made into a cylindrical shape so as to be in contact with the inner surface of the drum tube (3) can be used. There is. FIG. 7 is a schematic view showing the protrusion on the side of the drum flange (7). One drum flange (7) is provided with an internal electrode (25) and an annular electrode (26) that serve as contacts at the tip of a protrusion on the side surface. Two types of annular electrodes with different diameters may be used as contacts. FIG. 8 is a schematic diagram showing a longitudinal section of the drum flange (7). The internal electrode (25) and the annular electrode (26) are each inserted up to the side of the drum flange (7) facing inside the photoreceptor drum (2), and one end thereof is connected to the control circuit (21). There is.

The photosensitive drum (2) is provided with flanges (22) installed on the side plates (9) at the protruding portions of drum flanges (7) at both ends thereof, and bearings (8) installed on the flanges (22). Supported through.

Each electrode (25) is provided on the side plate (9) on the side of the drum flange (7) having the internal electrode (25) and the annular electrode (26).
) (26) A brush (24) is fixed so as to be in contact with the top.

The brushes (24) are each connected to an AC power source (23).

In the above-mentioned conventional drum heater device in which the length is 7', sliding members such as brushes wear out and require periodic replacement. Further, problems arise such as failure to stably supply electric power due to poor contact between the sliding parts and malfunction of a control device such as a microcomputer due to generation of electrical noise.

The present invention has been made in view of these points, and an object of the present invention is to provide a drum heater device that does not require power supply means based on contact of sliding members or the like.

In order to achieve the above-mentioned purpose of "i", the drum heater device of the present invention has the following features:
A drum heater device that warms a photoreceptor drum having a photoreceptor on its outer surface, the drum heater device comprising a spindle fixedly disposed on the central axis of the photoreceptor drum, and one end fixed to the spindle. one end is fixed to a pressing spring and the support shaft,
It is composed of a shape memory means that contracts at a predetermined temperature, and a friction means fixed to the other end of the pressing spring and the shape memory means, respectively, so as to be able to press against the inner surface of the photoreceptor drum. ing.

According to the configuration of the present invention, the photoreceptor drum is warmed by heat generated by friction between the inner surface of the rotating photoreceptor drum and the friction means. When the temperature of the photoreceptor drum reaches, for example, a predetermined temperature, the shape memory means contracts and a gap is created between the inner surface of the photoreceptor drum and the friction means, so that the friction is no longer performed. When the temperature of the photoreceptor drum falls below a predetermined temperature, the pressing springs are extended and the friction is performed.

Therefore, the photosensitive drum can be maintained at a predetermined temperature without using electricity.

Back" L± Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the drum heater device of the present invention.

The support shaft (1) is arranged so as not to rotate on the central axis of rotation of the photoreceptor drum (2), and at least one end thereof (only the left end is shown in FIG. 1) is attached to the side plate (9) by a support shaft fixing member. (10
) is attached by. The photosensitive drum (2) is connected to a drum tube (3), a drum flange (7) at both ends of the drum tube (3), a bearing (8) provided on the inner peripheral surface of the drum flange (7), etc. It is configured,
It is supported by the support shaft (1) via a bearing (8). Incidentally, the outer surface of the drum tube (3) is coated with an arsenic-based photoreceptor, although this is not particularly necessary. Inside the photoreceptor drum (2) is a spring (5) that presses against a spring fixing member (12a) provided on the support shaft (1).
is installed. A friction member (4) as a friction means is attached to the other end of the pressing spring (5) via a spring fixing member (12a), and is attached to the inner surface of the drum tube (3) by the expansion of the pressing spring (5). It is installed so that it can be accessed. In addition, the spring fixing member (
12b) Shape memory alloy wings (6) as shape memory means
is installed. The other end of the shape memory alloy spring (6) is connected to the friction member (12b) via the spring fixing member (12b).
4). Furthermore, a photoreceptor drum (2)
In order to prevent the friction member (4) from rotating together with the spindle, a friction member rotation stopper (11) is fixed to the support shaft (1). The friction member rotation stopper (11) is arranged such that the friction member rotation stopper (11) contacts the tip of the friction member (4) in the rotational direction of the photoreceptor drum (2), and the friction member rotation stopper (11) The tip of the drum tube (3) is provided so that it does not come into contact with the inner surface of the drum tube (3).

Since the inner surface of the drum tube (3) rubs against the friction member (4) when the photoreceptor drum (2) rotates, it is preferable that at least the inner surface of the drum tube (3) is made of a wear-resistant material. . However, in order to efficiently and quickly transfer the generated frictional heat to the surface of the photoreceptor drum (2), it is preferable to use a material with good thermal conductivity. Not done. In order to generate a large amount of frictional heat in a short period of time, a drum coarse tube (3) is used.
Preferably, the inner surface is provided with unevenness or the like.

Therefore, the strength and thermal conductivity of the material of the drum tube (3).

Considering the uniformity of heat generation, etc., it is preferable to provide irregularities as appropriate.

As the pressing spring (5), the shape memory alloy spring (6) is used when the surface temperature of the photoreceptor drum (2) is less than a predetermined temperature.
) is not contracted, the friction member (4) is pressed against the inner surface of the drum tube (3) to generate frictional heat and raise the surface temperature of the photoreceptor drum (2) to a predetermined temperature. good. Therefore, the pressing spring (5) is pressed against the friction member (4).
) against the inner surface of the drum tube (3) is as follows:
The material, shape, and number of the pressing springs (5) can be selected and adjusted as appropriate. Both ends of the pressing spring (5) are attached to the support shaft (1) and the friction member (4), respectively, with a spring fixing member (1).
2a), but it is fixed to such an extent that when the pressing spring (5) extends, the friction member (4) can be pressed against the inner surface of the drum tube (3) using the supporting shaft (1) as support. That's fine.

The shape memory alloy spring (6) may be one that detects the temperature inside the photoreceptor drum (2) and contracts when the surface temperature of the photoreceptor drum (2) reaches a predetermined temperature. The predetermined temperature is usually 35 to 40°C, and when the surface temperature of the photoreceptor drum (2) is lower than the predetermined temperature, the shape memory alloy spring (6) is pressed against the friction member (4). Either it does not exert any force or it extends so as to press the friction member (4) against the inner surface of the drum tube (3). The material, shape, number, etc. of the shape memory alloy springs (6) may be appropriately selected depending on the strength of the force of the pressing spring (5), the sensitivity to the detected temperature, etc., and are not particularly limited. When the surface temperature of (2) reaches a predetermined temperature, the friction member (4) is moved from the inner surface of the drum tube (3) against the stretching force of the pressing spring (5)
) must be able to generate a shrinking force to the extent that it separates the frictional heat, thereby stopping or reducing the generation of frictional heat. For example, Fr! may shrink all at once at a set temperature to stop friction, or may shrink gradually and continuously at a set temperature. Reduces friction heat. Although a spring made of a shape memory alloy is used in this embodiment, resin may be used as long as it is a shape memory means that detects a specific temperature and deforms into a preset shape. Both ends of the shape memory alloy spring (6) are fixed to the support shaft (1) and the friction member (4) with spring fixing members (12b), respectively, but the shape memory alloy spring (5)
It suffices if it is secured with a hook or the like to the extent that it can withstand the tensile force between the support shaft (1) and the friction member (4) when it contracts.
It is not particularly limited to the examples.

The friction member (4) rubs against the inner surface of the drum tube (3) when the photoreceptor drum (2) rotates, so it should be made of a material that is wear resistant and has a high coefficient of friction, such as that used in automobiles. Asbestos, which is used for brake members, is used. Further, regarding the shape, etc., irregularities may be provided as appropriate so as to match the inner surface of the drum tube (3) with which it comes into contact. Further, as shown in FIGS. 4 and 5, the spring fixing member (12a) and the friction member (4) are arranged so that force is uniformly applied to the entire friction member (4) by the pressing spring (5) and the shape memory alloy spring (6). ) may be provided with a friction member stand (14). Friction member (4)
The number of friction members (4) is set appropriately depending on the device to which it is applied, but in order to prevent the friction member (4) from rotating to one end when the photoreceptor drum (2) rotates, as mentioned earlier, the number of friction members (4) is Preferably, the member rotation stopper (11) is fixed to the support shaft (1). The position where the friction member rotation stopper (11) supports the friction member (4) is not particularly limited as long as it prevents the friction member (4) from rotating; ) on the rotational direction side of the friction member (
4) Provided so as to be in contact with the tip. Further, the material, shape, etc. of the friction member rotation stopper (11) are not particularly limited, and for example, those made of the same material as the rod-shaped or plate-shaped support shaft (1) are used.

2 and 3 are sectional views taken along the line A--A in FIG. 1, showing an embodiment of the drum heater device of the present invention. FIG. 2 shows a state when the surface temperature of the photosensitive drum (2) is lower than a predetermined temperature, and the inner surface of the drum tube (3) and the friction member (4) are in contact with each other.

FIG. 3 shows a state when the surface temperature of the photosensitive drum (2) is higher than a predetermined temperature, and the inner surface of the drum tube (3) and the friction member (4) are separated from each other.

FIG. 4 is a perspective view showing another embodiment of the drum heater device of the present invention, and FIG. 5 is a cross-sectional view of the main part thereof.

In FIGS. 4 and 5, seven sweepers are installed on the spring fixing member (12a) so as to be inserted into the support shaft (1) at the center of the friction member stand (14) and the pressing spring (5). A member guide (13) is shown and each friction member detent (1
The structure is similar to that of the embodiment shown in FIGS. 1 to 3, except that the drum tube 1) is plate-shaped and provided over the entire length of the drum tube (3) up to both ends.

Although only one pressing spring (5) is shown in FIG. 4, in reality, each friction member (4) is provided with one or more pressing springs (5). The friction member guide (13) is provided with a spring fixing member (12a) to ensure that the pressing spring (5) operates at a proper position and to be inserted into the support shaft (1) in accordance with the expansion and contraction of the spring. ) is fixed at one end. the shape of the friction member stand (14) and the friction member guide (13);
Although the material is not particularly limited, it is usually made of metal, and the friction member (4) and the spring fixing member (12a) (1
2b), etc., are used.

Next, the operation of the drum heater device configured as described above will be explained based on FIGS. 1 to 3.

First, as shown in FIGS. 1 and 2, the friction member (4) is pressed against the inner surface of the drum tube (3) by a pressing spring (5). Drive means (not shown)
When the photosensitive drum (2) is rotated around the support shaft (1), the friction member (4) and the inner surface of the drum tube (3) rub against each other, and frictional heat is generated therebetween. When the surface temperature of the photoreceptor drum (2) reaches a predetermined temperature due to the generated frictional heat, the shape memory alloy spring (6) contracts and the friction member (4)
is pulled in the direction of the support shaft (1), and as shown in FIG. 3, a gap is created between the inner surface of the drum tube (3) and the friction member (4).

When the surface temperature of the photoreceptor drum (2) decreases and becomes lower than a predetermined temperature, the shape memory alloy spring (6) can no longer maintain its contracted state, and is stretched by the pressing spring (5) at the same time. The friction member (4) is pressed against the inner surface of the drum tube (3) by the elongation.

By repeating the above cycle, the photoreceptor drum (2)
The surface can be maintained at a predetermined temperature. Since this embodiment utilizes frictional heat as described above, it is particularly preferable to use it in a high-speed electronic copying machine in which the photosensitive drum (2) rotates at high speed.

In addition, the outer surface of the photoreceptor drum (2) is usually 35 to 40 degrees.
It is designed to be around C, preferably 37°C, but it is adjusted as appropriate depending on the type of photoreceptor to be deposited on the drum tube (3). In this embodiment, an arsenic-based drum is used as the photoreceptor drum (2), and this is because the arsenic-based drum can form an electrostatic latent image on the photoreceptor with relatively low exposure energy when exposed to light. If this is not the case, a photoreceptor drum (2) formed by vapor-depositing a selenium-tellurium alloy may also be used.

According to the present invention, since a sliding member such as a brush is not used as a power supply means, not only is periodic replacement due to wear unnecessary, but also the photoreceptor drum can be warmed,
There is no need to use means that require electricity, such as a heater or a control circuit, to maintain a predetermined temperature, and the cost of the drum heater device can also be reduced. In addition, since the frictional heat generated by the rotation of the photoreceptor drum is used, the shape memory means does not cause the operation of the control circuit, etc. due to contact failure of the sliding part or the generation of electrical noise. This has the effect that the surface temperature of the photoreceptor drum can be stably maintained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the drum heater device of the present invention, and FIGS. 2 and 3 show the drum heater when the surface temperature of the photosensitive drum is lower and higher than a predetermined temperature, respectively. FIG. 3 is a cross-sectional view taken along line A-A showing the state of the device. FIG. 4 is a perspective view showing another embodiment of the drum heater device of the present invention, and FIG. 5 is a cross-sectional view showing the main parts thereof. FIG. 6 is a longitudinal sectional view of a conventional example, FIG. 7 is a side view showing the main parts of the drum flange, and FIG. 8 is a longitudinal sectional view of the drum flange. (1) - Support shaft, (2)...photosensitive drum. (3) --- Drum tube, (4) --- Friction member. (5)-11 pressing spring, (6)--shape memory alloy spring. (7) - Drum flange, (8) - Bearing. (9)...-Side plate, (10)-Spindle fixing member. (11) - Friction member rotation stopper. (12a) (12b)---Spring fixing member. (13)...Friction member guide, (L4)-Friction member stand. (20)...-heater, (21)...-control circuit. (22) - Flange, (23) --- AC power supply. (24) --- Brush, (25) --- Internal electrode. (26) - One circular electrode.

Claims (1)

[Claims] (1) A drum heater device that warms a photoreceptor drum having a photoreceptor on its outer surface, which includes a support shaft that is rotatably disposed on the central axis of the photoreceptor drum, and one end fixed to the support shaft. a shape memory means having one end fixed to the support shaft and contracting at a predetermined temperature; and a shape memory means fixed to the other ends of the pressure spring and the shape memory means, respectively, to the photosensitive drum. and a friction means that can be pressed against the inner surface of the drum heater device.