JPS58118685A - Controlling device of constant-temperature for photosensitive body - Google Patents

Abstract

PURPOSE:To maintain a photosensitive body in a fixed temperature range at a high accuracy, by installing a resistance heating unit which heats the photosensitive body and an air blowing means for cooling to adjust the heating speed and the cooling speed. CONSTITUTION:Numerous air holes 5 are pierced through the shaft 4 of a photosensitive body drum and a cooling fan and a resistance heat generating unit 8 of nichrome wires, etc., at the downstream side in the flowing direction of the outside air are installed in a housing 6 at a side plate 12b side, and then, a shutter 10, whose blade opening is adjusted by a DC motor 11, is fitted to the right side of the housing 6. The surface temperature of a photosensitive body drum 1 is detected by a temperature sensor 12 to control the conducting electrocity to the heating unit 8 and the opening of the shutter 10 by a controlling device 13 based on the detected surface temperature of the drum 1. Therefore, the photosensitive body is maintained in a fixed temperature range at a high accuracy to maintain the photosensitive body under the condition when the fatigue is recovered, and to contribut to improve the quality of pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant temperature control device for heating a photoconductor used in an electrophotographic process to a constant temperature to recover from fatigue, and in particular, the present invention relates to a constant temperature control device that is equipped with a cooling function in addition to a heating function. Furthermore, the present invention proposes a constant temperature control device for a photoreceptor, which improves temperature control accuracy by being configured to adjust the heating rate and cooling rate. In some cases, as the temperature decreases, the skin potential increases and the sensitivity decreases. Such a photoreceptor fatigue phenomenon causes a decrease in image density, which is particularly inconvenient when developing an electrostatic latent image on the surface of the photoreceptor. That is, the potential of the developing electrode is set to be sufficiently lower than the potential of the image area on the surface of the photoreceptor, and higher than the background potential of the surface of the photoreceptor. The toner charged to the opposite polarity can be attached only to the image area, and the toner does not adhere to the background area, resulting in a clear image.

However, if the temperature of the photoreceptor decreases and the background potential increases, the potential of the background will become higher than the potential of the developing electrode, and in this case, toner will also adhere to the background during development, resulting in contamination by toner. occurs, resulting in a deterioration of image quality.

For this reason, conventionally, in order to maintain a high background potential, a method has been adopted in which the photoreceptor is heated to recover from its fatigue. By the way, this type of fatigue recovery device includes one that heats with an infrared lamp, one that heats with hot water, and one that continues corona discharge for a long time, but all of these devices are processed on the outside of the photoreceptor. As a result, the overall structure of the electrophotographic apparatus becomes complicated, causing problems in the arrangement of the transfer device and other devices, and the temperature of the entire electrophotographic apparatus rises, resulting in increased power consumption and other inconveniences. There is. On the other hand, there are devices that heat the photoreceptor by incorporating a heating means into the photoreceptor, but like the above-mentioned fatigue recovery devices, the installation space is limited and the focus is only on heating the photoreceptor. The temperature was controlled by turning the heating means on and off. Therefore, the cooling of the photoreceptor depends on natural cooling when the heating means is set to 7, and cooling takes a long time, making it extremely difficult to maintain the photoreceptor within a constant temperature range. Ta.

The present invention has been made in view of the above points, and has a function of not only heating the photoreceptor but also forcibly cooling the photoreceptor, and furthermore, the photoreceptor is configured so that the heating rate and cooling rate can be adjusted. It is an object of the present invention to provide a constant temperature control device for a photoreceptor, which can maintain the photoreceptor within a certain temperature range with high precision, can be realized with an extremely simple configuration, and does not cause any inconvenience in terms of installation space. A constant temperature control device for a photoconductor according to the present invention is a device for constant temperature control of a photoconductor used in an electrophotographic process, which includes an air blowing means for ventilating the photoconductor, and a ventilation area between the blowing means and the photoconductor. A heating element disposed in the photoreceptor, a heat generation control means for adjusting the heat generated by the heating element based on the temperature of the photoreceptor, and an air blowing control means for adjusting the amount of air blown by the air blowing means. It is.

Hereinafter, a case in which the present invention is applied to an electrophotographic copying machine will be specifically described with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. A cylindrical drum shaft 4 is attached to side plates 12a and 12b of the copying machine main body with its longitudinal direction horizontal, and disk-shaped supports are provided on the outer circumferential surface of both ends of the drum shaft 4 via bearings 3a and 3b, respectively. The plates 2a + 2b are rotatably attached to the drum shaft 4 1, and the cylindrical photosensitive drum l has both longitudinal ends thereof externally attached to the support plate 2as2b.
The photosensitive drum l is rotated at a constant speed around the p-drum shaft 4 by a rotational drive device (not shown). The photosensitive drum 1 is formed by forming a photosensitive layer made of a photoconductive substance such as selenium or an arsenic-selenium alloy on the circumferential surface of a conductive cylindrical base such as aluminum. , a uniform charging device, an image exposure device, a developing device, a transfer device, a cleaning/cleaning device, a static eliminating device (all not shown), etc. are arranged in the rotating direction. Therefore, as the photosensitive drum 1 rotates,
The circumference l is uniformly charged, and the document image is exposed to uniform #
The accumulated charges are selectively removed and an electrostatic latent image corresponding to the original image is formed. Next, toner charged to the opposite polarity to the S image charge is supplied to the electrostatic latent image and visualized.
This toner image is transferred onto a transfer material by a transfer device. Then, untransferred toner remaining on the surface of the photosensitive drum 1 without being transferred is removed by a cleaning device, and the peripheral surface is neutralized by a static eliminator and subjected to the next copying process.

On the other hand, the peripheral wall of the drum shaft 40 has a large number of ventilation holes 5 uniformly distributed in the longitudinal and circumferential directions, and the end of the side plate 12a141 of the drum shaft 4 is closed, and the side plate 12
The end b@ is open and the housing 6 is connected to this opening. Inside the housing 6 is a fan 7 which is a means of blowing air.
A fan 7Fi is normally driven and rotated at all times to feed external air from outside the copying machine body into the drum shaft 4, pass through the ventilation hole 5, and cool the inner periphery of the photoreceptor drum 1. The downstream shaft of the fan 7 in the outside air ventilation direction in the housing 6 is designed to introduce outside air to the inner peripheral surface of the photoreceptor drum 1 and make it flow. A resistance heating element 8 such as a wire is housed and installed so as to be interposed in the ventilation area by the fan 7.The resistance heating element 8 has an AC '#I! A c source 9 is connected, and the resistive heating element 8 is energized to generate resistance heat.
The on/off control of the energization is performed by the control device 13. An opening 6a for introducing external air into the housing 6 is formed on the side surface of the nozzle 6 opposite to the side surface connected to the drum shaft 4. A shutter 10 is provided on the outer surface of the housing 6 so as to completely cover the opening 6a. FIGS. 1, 2, and 3 are plan views of the shutter 10. The shutter 10 has a substantially semicircular fixed blade 10a and a movable blade 10b. At the peripheral edge of the fixed blade 10a, the fixed blade 10a is fixed to the side surface of the housing 6 such that it is separated from the side surface of the housing 6 by the thickness of the movable blade 10b. Movable blade 10b
ii A gear is provided on its peripheral surface, and its diameter is slightly shorter than the diameter of the fixed blade 10a. And the blade 10a
, 10b are both semicircular in shape with their chords located slightly outside the center of the circle. Therefore, the movable blade 10b rotates around this coupling shaft 10C.
When the movable blade 10b rotates to a position where the overlapping portion with the fixed blade 10a is minimized, the opening 6a is closed by the movable blade 10b, and the o'J movable blade blade 1
When the opening 6a is rotated to a position where the overlapping portion with the 0b constant blade 10a is maximized, the opening 6a has the maximum opening degree. A DC motor 11 (see Fig. 1) is installed at a suitable location in the main body of the copying machine, with a gear lla attached to the tip of its drive shaft meshing with a gear on the circumference of the movable blade Job. 11 rotates the movable blade 11b to adjust the degree of opening of the °C opening roller 6a. This motor 1
The control device 13 controls the rotation of the shutter 10, and further controls the opening degree of the shutter 10 by rotating the movable blade 10b.

A detection signal from a temperature sensor 12 disposed near the circumferential direction of the photoreceptor drum 10 is inputted to the control device 13, and the control device 13d receives the detection signal of the photoreceptor drum l detected by the photoreceptor drum 12 once. Based on the temperature, the energization to the resistance heating element 8 and the opening degree of the shaft 10 are controlled.

Next, regarding the control mode by the control device 1113, see below.
The explanation will be based on the table below.

Table 1゛. is a predetermined temperature of the photoreceptor drum 1 that should be maintained in order to recover from fatigue of the photoreceptor drum 1, and the temperature T of the photoreceptor drum 1 detected by the temperature sensor 12 is lower than the predetermined holding temperature T0. If the temperature is also high, the AC power supply 9 that supplies power to the resistance heating element 8 is turned off, and the detected temperature T is set to a predetermined temperature T9.
If the conditions are as follows, the AC power source 9 is turned on to energize the resistance heating element 8 to cause the pushpiece to generate resistance heat. Therefore, when the photoreceptor drum l becomes too hot, the detected temperature T becomes the standard temperature 'f'H(T)1 for continuous construction, taking controllability etc. into consideration.
>'Bird) If the control device 13 exceeds the motor 11
The movable blade 10b is rotated in the direction in which the movable blade 10b and the identification blade 10a overlap, and the shutter 1 is rotated.
With an opening degree of 0 as a dog, the flow passes through the opening 6a and the Nouji puffer 6
On the other hand, when the detected temperature T is between TH and Il+, the control device 13 increases the motor 1 so that the opening degree of the shutter 10 becomes small.
1 to reduce the amount of external air introduced into the No-Uji puffer fish 6. Further, the detected temperature 'V of the photoreceptor drum 1 by the temperature sensor +f12 is set to a predetermined holding temperature '1゛o.
If the condition is below, the control device fii 13 increases the opening degree of the 7-way valve 10 by the same operation as described above (increases the external air blowing lid). Then, the detected temperature T is a reference temperature g'l'L (TI
.

In the device of the present invention configured as described above, the fan 7
is constantly rotated when the copying machine is powered on, and the photosensitive drum 1 is rotated when the copying switch is turned on. The rotation is controlled by Therefore, when the detected temperature T of the photosensitive drum 1 is lower than TL, such as when the copying machine has just been left unused for a long time, Fi('
I'<'1'L), the resistance heating element 8 is energized, and the opening degree of the /yasota 10 is set small. Then, the resistance heating element 8 #i generates resistance heat, and the outside air introduced into the Ujifugu 6 by the fan 7 is heated by the heat of the resistance heating element 8.
The hot air is fed into the drum shaft 4. stop"〔,
This hot air is fed to the inner peripheral surface of the photoreceptor drum 1 through the ventilation holes 5, and the hot air circulates through the inner peripheral surface of the photoreceptor drum 1. As a result, the photoreceptor drum 1 receives heat transferred from the hot air and is heated, increasing its temperature. However, since the amount of air blown is low, the amount of heat generated by the air is unnecessarily diffused and the temperature of the photoreceptor drum 1 is lowered. Since it is not stored away, the photoreceptor drum 1 can be heated with high efficiency, and its temperature increase rate is high. Next, when the detected temperature T rises above TL, the resistance heating element 8 remains energized, but the opening degree of the shutter 10 is set to a large degree. In this case, although the amount of heat generated by the resistance heating element 8 is constant, the amount of air blown becomes large, so the temperature increase rate of the photoreceptor drum 1 heated by the hot air ventilation decreases, and the temperature of the photoreceptor drum 1 decreases. is gradually heated to a predetermined temperature T.

On the other hand, when the detected temperature T of the photoreceptor drum 1 exceeds the predetermined temperature T0, the power supply to the resistance heating element 8 is turned off and the air blow t is set to a small value. In this case, the outside air introduced into the housing 6 by the fan 7 is directly fed into the drum shaft 4, and the low-temperature outside air circulates through the inner peripheral surface of the photoreceptor drum 1. Due to the convection of this low-temperature outside air, the photoreceptor drum 1 is forcibly cooled, and the temperature of the photoreceptor drum 1 is lowered, but since the amount of air blown is small, the rate of temperature drop is slow. When the detected temperature T rises above TH, the amount of air blown is increased and the photosensitive drum 1 is rapidly cooled.

In this way, when the temperature T of the photosensitive drum 1 detected by the temperature sensor 12 becomes equal to or lower than the predetermined holding temperature %, d
1 resistance heating element 8 is turned on, hot air is supplied to the inner peripheral surface of photoreceptor drum 1, and T becomes T. If the temperature becomes higher, the resistance heating element 8 is de-energized and low-temperature outside air is supplied to the inner peripheral surface of the photoreceptor drum 1. In addition, if the temperature T of the photoreceptor drum 1 is too high, is (T>'1'H),
If the low-temperature outdoor air blower lid becomes large and the temperature is too low, 1ri
(T<TL), since the amount of hot air blown is small, not only the heating rate of the photoreceptor drum 1 but also the -1 cooling rate is extremely fast.
Furthermore, if the temperature of the photoreceptor drum 1 is too low, it can be raised at a higher rate, and conversely, if it is too high, it can be lowered at a higher cooling rate. Therefore, the temperature '1 of the photosensitive drum 1
can be controlled with high precision to a predetermined temperature +llo.Furthermore, since the heating is performed using hot air, uneven heating of the photoreceptor drum 1 is extremely small.

Note that the installation position & of the resistance heating element 8 is as in the above embodiment.
It is also possible to house and install it inside the drum shaft 4 instead of inside the housing 6. Moreover, it goes without saying that the control mode by the control device 13 is not limited to the above-mentioned one. for example,
When energizing the resistance heating element 8, the amount of resistance heat generation may be adjusted by adjusting the energization range based on the temperature of the photoreceptor drum 1, and the opening degree of the shutter lO may be set as described above. The number of buildings is not limited to two, large and small, but may be configured in three or more ways. In addition, a thermistor is used as the temperature sensor 12, and its resistance 1j and Tanabata 11
By programming the relationship between the energization time (the rotation device of the morph 11) and the energization time (the rotation device of the morph 11) in the control device 13, it is also possible to perform air blowing amount control such as tl[.

Next, a second embodiment of the present invention will be described based on FIG. 4 showing a longitudinal cross-sectional view thereof. In this embodiment, the blowing means and the heating element are housed inside the photosensitive drum.

In this embodiment, a cylindrical drum shaft 14 having a slightly shorter diameter than the drum shaft 4 is connected to the side plates 12a and 12b of the copying machine main body.
It is installed with its longitudinal direction horizontal. Disc-shaped support plates 2a and 2b are added to the outer peripheral surface of both ends of the drum shaft 140 via bearings 3a+3b, and the support plate 2a.

The photoreceptor drum 1 is fitted onto the outer surface of the photoreceptor drum 2b, and the photoreceptor drum 1 is driven to rotate at a constant speed.

Inside the photoreceptor drum 1, a circular resistance heating element 15 having a diameter slightly shorter than the diameter of the inner peripheral surface of the photoreceptor drum 1 is attached to the drum shaft 14. The resistance heating element 15 is made of silicon carbide (SiC), for example, and is formed into a cylindrical shape by winding a band-shaped heating element in a spiral shape. Both ends of the spiral resistance heating element 15- are connected to an AC power source 9 through a conductive wire housed in the drum shaft 14, and the AC power source 9 is connected to a control device 19, and is connected to the AC power source 9 near the cylindrical surface of the photoreceptor drum 1. Based on the temperature of the photoreceptor drum 1 detected by the provided temperature sensor 12, a control device t19 controls on/off the energization of the resistance heating element 15.

Then, when the resistance heating element 15 is energized, a current flows through the spiral band-shaped heating element in its longitudinal direction, and the resistance heating element 15 becomes a cylindrical heat generation source due to the resistance heating.

1 on the inside of the end of the side plate 12 bllll of the resistance heating element 15
A pair of fans 16a and 16b is installed on the drum shaft 14 (air intake holes 17a and 171 formed in the support plate 2b by the rotation of the fans 16a and 16b) and air inlets formed in the side plate 12b. Outside air is introduced into the inside of the photoreceptor drum 1 through the intake ports 18a and I8b, and the resistance heating element 15
The inside of the photoreceptor drum 1 is ventilated and blown out from the spiral gap onto the inner peripheral surface of the photoreceptor drum 1, thereby supplying outside air to the inner peripheral surface of the photoreceptor drum 1. Fan 16a, 1
The air blow control 61) is performed by the control device 19 in conjunction with the on/off control of energization to the resistance heating element 15 based on the above table. That is, the temperature [T] detected by the temperature sensor 12 of the photoreceptor drum l is T. In the case of a twisted cylindrical knit, the power to the resistance heating element 15 is turned off and the detected temperature T is the predetermined temperature T. If it is below, energization to the resistance heating element 15 is turned on. Then, when the detected temperature 'V is higher than rH and the detected temperature T is T. ≧T, zTL, the control device 19
By controlling the phase of energization to b, the fans 16a and 164) are rotated at high speed to introduce outside air with a large air flow rate, and when the detected temperature T is in the range of TH≧T > To and T is lower than TL. In this case, the control device 19 controls the phase of energization of the fans 16a1 and 16b to
The fans 16a and 16b are rotated at low speed to introduce outside air with a small blast of air.

When the photoreceptor drum 1 is controlled at a constant temperature by the apparatus according to this embodiment, the temperature of the photoreceptor drum I can be controlled to a predetermined temperature Ill at a very low temperature and quickly. That is, when the detected temperature 'r of the photoreceptor drum 1 is extremely low by °C (T<TL), the resistance heating element 15 is energized and generates resistance heat, thereby heating the photoreceptor drum l.Then, the fan 16 rotates at a low speed.
The air inside the photoreceptor drum 1 is agitated by the weak winds 3 and 16b, thereby eliminating uneven heating, and the temperature of the photoreceptor drum 1 is increased at a bulk temperature increase rate. and,
When the detected temperature T exceeds TL, the fans 16a and 16b are rotated at high speed to send strong wind to the inner peripheral surface of the photoreceptor drum 1, causing heat diffusion and reducing the temperature increase rate of the photoreceptor drum 1. be lowered. On the other hand, the detected temperature T is the predetermined temperature "
If the value exceeds vo, the power supply to the resistance heating element 15 is turned off, and the fans 16a and 16b are switched to low speed rotation. Then, the low-temperature outside air passes directly through the inner peripheral surface of the photoreceptor drum 1 and cools the photoreceptor drum l, but the photoreceptor drum l continues to warm up and the detected temperature T becomes 0T. ) If it exceeds I, the fans 16a and 16b
is switched to high-speed rotation, and photoconductor drum 1 is rotated at a high cooling rate.
is cooled.

In this way, also in this embodiment, hot air and cold air are selectively supplied to the inner circumferential surface of the photoreceptor drum 1 based on the detected temperature T of the photoreceptor drum 1, so that the photoreceptor drum 1 is heated or Since the temperature increase rate or the cooling rate is adjusted by controlling the amount of air blown, the temperature of the photoreceptor drum l can be quickly and accurately controlled at a constant temperature. Note that the air blowing amount control in this embodiment is not based on the phase control of energization as described above, but rather on the air inlet 18. , 181) may be provided with a shutter, and the amount of air blown may be controlled by adjusting the opening degree of the shutter. Further, in the embodiment shown in FIG. 1, the air blowing amount may not be controlled by adjusting the opening degree of the shutter 10, but may be controlled by controlling the phase of energization to the fan 7.

As explained in detail above, the device of the present invention has not only the heating +4 function of the photoconductor but also the cooling function, and is configured so that the heating rate and cooling rate can be changed and set. The control accuracy when controlling the photoreceptor within a predetermined temperature range is extremely high, and it is possible to avoid fluctuations in the physical properties of the photoreceptor and maintain it in a uniform fatigue recovery state, contributing to improved image quality. The invention is a book that can be widely applied not only to Hiroko's photocopying wax, but also to various electrophotographic devices that use photoreceptors, such as electrophotographic printing machines.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of the present invention, FIGS. (Explanation of symbols) 1... Photosensitive drum 4, 14... Drum shaft 5
...Ventilation holes 7.16a, 16b...Fan 8.15...Resistive heating element 9...AC power supply 10.../Yatsuta 10a...Fixed blade 10b...Movable blade 1
2...Temperature sensor 13.19...Control device patent applicant Ricoh Co., Ltd.

Claims (1)

[Claims] 1. A device for controlling a photoconductor used in an electrophotographic process at a constant temperature, including a blowing means for ventilating the photoconductor, a heating element disposed in a ventilation area between the blowing means and the photoconductor, and the above-mentioned A constant temperature control device for a photoreceptor, comprising a heat generation control means for adjusting the heat generation of the heating element based on the temperature of the photoreceptor, and an air blowing control means for adjusting the amount of air blown by the air blowing means.