JPS6169087A - Photosensitive drum - Google Patents

Abstract

PURPOSE:To raise quickly the temperature of a photosensitive layer by providing the photosensitive layer on the surface of a metallic cylinder and providing a heating body having a position temperature coefficient and a conductive metallic layer on the inside face of this cylinder and applying a voltage across the metallic cylinder and the conductive metallic layer. CONSTITUTION:A photosensitive layer 21 is formed with Se, CdS, or the like on the surface of a cylinder 20 consisting of Al. A resistance heating body layer 22 which consists of ceramics (SiC, LaCrO3, or the like) having a positive temperature coefficient is provided layer 23 consisting of a stainless steel or the like and a heat insulating ceramic layer 25 are formed on the inside face of the layer 22. A voltage is applied across the Al cylinder 20 and the metallic layer 23 by a slip ring 24 to allow the resistance heating layer 22 to emit heat. When the temperature is raised, the resistance of the resistance heating layer 22 is increased because of the positive temperature coefficient and limits a current to keep the temperature in a certain range. Thus, the temperature is raised quickly with the simple device to shorten the waiting time, and the power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a photosensitive drum used in an image forming apparatus such as an electrophotographic apparatus.

[Background of the invention]

First, as an example of an image forming apparatus using a photoreceptor drum, a conventionally commonly used electrophotographic copying machine will be described with reference to FIG. In FIG. 5, numeral 1 denotes a photoreceptor drum, which is a cylinder made of metal, generally aluminum, with a photoreceptor layer of S., CdS, etc. provided on the surface thereof, and is rotated in the direction of the arrow shown. The illustrated electrophotographic copying machine has a photosensitive drum It- which rotates in the direction of the arrow.
, the document 3 is uniformly charged by the charger 2, and then illuminated by the document 3t-land 4 to form a latent image on the photoreceptor through the short focus lens array 5. to fully develop the latent image, and on the other hand, the transfer sheet 10f is conveyed through the guides 11 and 13 by driving the paper feed roller 9 and the register roller 12, and the toner image is transferred by the charger 7. There is. After the transfer, the transfer sheet is peeled off from the photosensitive drum by a separation belt 14, passes through a conveyance belt 15, a fixing paper guide 17, and then passes through a fixing device 16.
It is established in Further, residual toner on the photoreceptor is removed by a cleaning blade 8. This is the default process.

Conventionally, in the above-mentioned electrophotographic copying machines, it is necessary to maintain the photoreceptor layer, such as CdS, provided on the surface of the photoreceptor drum at a constant temperature, so there is a
An 8ft heater with a power of ~30W is installed. However, when the heater is turned on after the heater is turned off, it takes several tens of minutes for the temperature of the photoreceptor layer on the surface of the drum to rise to a predetermined temperature. For this reason, conventional devices have a mechanism that does not turn off the power to the heater of the photoconductor drum even if the main power is turned off, and in the case of a thermal fixing type copying machine, the machine is operated only by the wait time of the fixing roller. Normally, it is possible to start. However, in this case, the power consumption of the machine is large, and if the power to the photosensitive drum is turned off, it takes several tens of minutes to start the machine.

In order to eliminate such difficulties and shorten the wait time by rapidly increasing the temperature of the photoreceptor layer of the photoreceptor drum, a heater installed near the center of the drum must be heated to a high temperature of 1loooC or higher. This may cause temperature unevenness, and
In a high temperature area of 60° C. or higher, toner blocking may occur.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a drum for an image forming apparatus in which the temperature of the photoreceptor layer of the photoreceptor drum can be raised uniformly and quickly, and power consumption can be reduced.

[Summary of the invention]

The photoreceptor drum according to the present invention is characterized by having a photoreceptor layer of Ss, CdS, etc. on the surface of a metal cylinder. A resistive heating element layer and a conductive metal layer are provided, and a means for applying a voltage between the metal cylinder and the conductive metal layer is provided.

Preferably, a heat insulating ceramic layer 19 is provided on the inner surface of the conductive metal layer.

[Embodiments of the invention]

The illustrated embodiment will be described below.

FIGS. 1 and 2 show an embodiment of a photosensitive drum according to the present invention. In the figure, 20 is an aluminum cylinder,
21 indicates a photoreceptor layer made of 5enCdS or the like provided on the surface thereof. The inner surface of the cylinder 20 is made of ceramic with a positive temperature resistance coefficient, such as SiC, LaCrO3 or Ba.
A resistive heating element layer 22 made of TiO3-based semiconductor ceramic is provided, and a conductive metal layer 23, such as a stainless steel layer, is further provided on its inner surface. Means for applying a voltage between the cylinder 2o and the metal layer 23 is provided, thereby causing the resistance heating element layer 22t made of ceramics to generate heat.

The arrangement of this resistance heating element is a spiral type or a third type.
As shown in the figure, a bent shape may be considered.

Further, as a means for applying voltage between the aluminum cylinder 20 and the metal layer 23, since the photosensitive drum is a rotating body, it is necessary to provide a connection such as a slot or a 76 ring 24 as shown in FIG. There will be.

In the embodiment shown in FIG. 1, a layer 25 of heat insulating ceramic or camphorax is further provided on the inner surface of the metal layer 23 in order to further dissipate the heat generated by the resistance heating element toward the surface of the drum. .

As mentioned above, the photoreceptor drum according to the present invention utilizes as a heating element a resistive heating element made of ceramic having a property known as positive temperature resistance coefficient (PTC). The preferred ceramic material is called a ferroelectric material and has a low resistance up to a certain temperature known as the Curie temperature, and once this temperature is reached, the electrical resistance value is typically 50°C within a range of 10°C or less. ~5000
It has the characteristic of increasing to Ω. Therefore, such characteristics can be utilized to form a thermostat of its own. Moreover, since its effect is limited to a significantly narrow temperature range inside, oscillating changes in temperature can be minimized. Devices utilizing such ceramics have significant advantages over conventional temperature control methods.

In other words, the use of these ceramic materials provides superior temperature control, eliminates the need for a conventional thermostat, and thus provides a more economical device, which eliminates the traditional problem of contact breakage. It is possible to obtain a device that is more reliable than those that utilize conventional thermostats, which tend to occur. In particular, when BaTiO3 semiconductor ceramics is used as a resistance heating element, it exhibits resistivity-temperature characteristics as shown in FIG. In the case of the present invention, the operating temperature is about 50 to 60°C in summer, so the positive characteristic range is within this range.
It is even more desirable to perform a semiconductor processing using a valence control method in which a small amount of a substance such as the like is added.

Plasma spraying is the method for attaching the BaT105 semiconductor ceramic and gas layer! 0μm～ljl! A layer of about II can be easily formed. The SiC layer is deposited by plasma discharge in an atmosphere of SiH4 and CH. Furthermore, the metal layer can be formed with a thickness of 10 μm or more using plasma spraying method, etc.
A thickness of about 2w can be easily formed.

f' The heat insulating ceramic layer can also be formed in a similar manner to a thickness of about 10 μm to 211111 μm.

According to the layer structure obtained in this way, it is possible to uniformly raise the temperature of the photoreceptor drum surface to about 50°C in a few minutes at a low voltage of 20 to 30V and because the heating element is attached directly to the drum. It is possible to raise the

〔Effect of the invention〕

As explained above, the photoreceptor drum according to the present invention is produced by providing a resistance heating element, a conductive metal layer, and preferably a cross-sectional ceramic or wood layer on the inner surface of a cylinder made of aluminum or the like having a photoreceptor layer on the surface. , it is possible to achieve the effects of shortening wait time and reducing power consumption.

[Brief explanation of drawings]

1 and 2 are longitudinal and transverse sectional views showing one embodiment of the photosensitive drum according to the present invention, FIG. 3 is a partially cutaway perspective view thereof, and FIG. 4 is a resistance of a resistance heating element. FIG. 5, which is a diagram showing temperature characteristics, is a schematic diagram showing an example of a conventional general electrophotographic apparatus. 1... Photosensitive drum 2... Charger 3... Document 4... Illumination rung 5... Lens array 6... Developing sleeve 7... Transfer charger
8...Cleaning blade 9...Paper feed roller 10...Transfer sheet 11.13.17.
・Sheet conveyance guide 12 ・Reso roller 14 ・
... Separation belt 15 ... Conveyance belt 16 ... Fixing roller 18 ... Heater 20 ... Cylinder
21... Photoreceptor layer 22... Resistance heating element layer
23... Metal layer 24... Slip ring 25.
...Insulating ceramic layer 30...Resistance heating element
31...Thermal element No. 2 Fig. Z Fig. 4 (31L garden CC) Fig. 5

Claims (2)

[Claims] (1) In a photoreceptor drum in which a photoreceptor layer of Se, CdS, etc. is provided on the surface of a metal cylinder, a resistance heating layer made of ceramics having a positive temperature resistance coefficient and a conductive metal layer are provided on the inner surface of the cylinder. , a photosensitive drum characterized in that a means for applying a voltage between the metal cylinder and the conductive metal layer is provided. (2) The photosensitive drum according to claim (1), wherein a heat insulating ceramic layer is provided on the inner surface of the conductive metal layer.