JPH0844435A - Heating temperature controller - Google Patents

Abstract

PURPOSE:To provide a heating temperature controller for shortening the rise time of a heating device having the slowest temperature rise time and shortening the whole rise time of the device by controlling a previously set current supply rate for the heating device so as to increase it. CONSTITUTION:The heating temperature controller is provided with plural heating devices 20, 40 respectively having heating means 13, 33 for heating respective targets 11, 31 by current supply, temperature detecting means 17, 37 for detecting the temperature of the targets 11, 31 and lower current supply ratio controlling means 15, 35 for controlling the current supply rates of respective heating means 13, 33 based upon detected temperature, plural current supply rate detecting means 21, 41 for detecting the current supply rates of the means 13, 33 of plural heating devices 20, 40, a current supply rate comparing means 23 for comparing respective current supply rates detected by respective means 21, 41 and discriminating the heating device having the most delayed temperature rise, and an upper current supply rate controlling means 44 for controlling the heating device discriminated by the means 23 as a device whose temperature rise is most delayed so as to change the current supply rate of the heating means in the discriminated heating device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of heaters such as a printer or a copying machine when a transfer photosensitive drum needs to be heated, and a fixing heating roller heater. And a heating temperature control device for controlling the heating temperature of these heating devices.

[0002]

2. Description of the Related Art OPC (organic photoconductor) -based materials are often used for conventional photosensitive drums for transfer in printers and the like, but the cost of these OPC-based photosensitive drums is low. Although it has an advantage, it has poor durability. Therefore, when durability is required, an a-Si (amorphous silicon) -based material is used. The a-Si-based material has the advantages of being the material having the highest mechanical strength and having a high-speed photoresponse and good sensitivity.

However, since this a-Si type photosensitive drum is exposed to ozone generated by corona discharge in the charging process, silica (SiO) is formed on the surface of the drum. Since this silica is hydrophilic, water molecules are adsorbed on the surface of the photosensitive drum when the humidity of the air around the photosensitive drum is high. As a result, the electrical conductivity of the surface of the photosensitive drum changes, the charge retention function during corona charging is significantly impaired, and so-called "image deletion" occurs in which the electrostatic latent image formed on the surface of the photosensitive drum is disturbed.

As one of the methods for preventing the phenomenon of "image deletion", conventionally, a heater for heating a drum is provided inside the photosensitive drum, and a-
By heating the Si drum to a constant temperature, water molecules adsorbed on the surface of the drum are removed by evaporation to prevent the occurrence of "image deletion" (Act No. 1-3420).
No. 5, Japanese Utility Model Publication No. 1-34206).

In such a conventional a-Si type photosensitive drum, it is necessary to shorten the rise time from when the power is turned on to when the temperature is raised to the ready-to-transfer state. This can be easily achieved with an electric heater. However, using a high-power heater not only increases the power consumption of the entire apparatus, but it also inevitably occurs when the temperature of the photosensitive drum is kept at a constant target temperature by heating with the high-power heater. The temperature difference between the chute (passing the target temperature and deviating from the target temperature by some amount) and the target temperature after the target temperature is exceeded and then stopped is large. For this reason, the charge holding function at the time of corona charging is affected by the temperature change, and there is a problem that the electrostatic latent image becomes unstable and reliable image formation cannot be performed.

In order to solve such a problem, aS
A low-power heater may be used as the heater of the i photoconductor drum, but if this is done, the rise time becomes longer and the waiting time becomes longer. On the other hand, in a printer device or the like, a heating roller is used to fix the toner image transferred to the transfer paper, and the heater of this heating roller is the same as the heating heater for the drum of the photosensitive drum. A small power heater is also used to prevent an increase in power consumption.

Conventionally, as a temperature control device, by controlling the energizing rate (energizing amount per predetermined time) of the heater by changing the energizing pulse width, pulse period, etc. depending on the detected temperature, the temperature is controlled to be close to the target temperature. In addition to eliminating the unstable state of the energization operation at the same time, there is an attempt to improve the responsiveness of the energization to the temperature change (Japanese Patent Publication Sho 53-
No. 34274), such a temperature control device is described in the above a.
It can also be used as a heater for a Si photosensitive drum or a heating roller.

[0008]

However, when a plurality of heating devices are used in one device as described above,
Since the rise time of the temperature of each heating device is different, the rise time of the temperature of the entire device is determined by the rise time of the slowest heating device.In other words, if the rise time of the temperature of one heating device is slow, the rise time of the entire device is increased. There was a problem that the time would be late. Particularly in recent years, a request for a quick start, that is, a request for shortening the waiting time by shortening the rise time of temperature as much as possible has been intensifying, which may result in a result contrary to this request.

In view of the above problems, the present invention shortens the rise time of the heating device having the slowest temperature rise time by controlling the heating device so as to increase the preset duty ratio of the device. An object of the present invention is to provide a heating temperature control device that shortens the entire rise time.

[0010]

In order to solve the above problems, the heating temperature control device according to the present invention has the following configuration. (1) It has a heating means for heating an object by energization, a temperature detecting means for detecting the temperature of the object, and an individual duty ratio control means for controlling the duty ratio of the heating means based on the detected temperature. A plurality of heating devices, a plurality of duty ratio detection means for detecting the duty ratio of each heating means of the plurality of heating devices, and a comparison of the respective duty ratios detected by the plurality of duty ratio detection means with the highest temperature Of the heating device for discriminating the heating device whose rise is delayed, and the heating device for increasing the electrification factor of the heating device of the heating device for which the conduction ratio comparing means discriminates that the rise of the temperature is delayed most. And an upper duty factor control means for controlling.

(2) In the heating temperature control device having the structure (1), the control of the energization rate performed by the individual energization rate control means is performed by changing the pulse width and the pulse width of the energization for a predetermined time. Control the amount of electricity.

(3) In the heating temperature control device having the above-mentioned configuration (1), the control of the duty ratio performed by the individual duty ratio control means is as follows.
The energization amount per predetermined time is controlled by changing the pulse period while the energization pulse width is constant.

(4) In the heating temperature control device having the above structure (1), the individual duty ratio control means controls the duty ratio.
The energization amount per predetermined time is controlled by changing the pulse amplitude height while the energization pulse period and pulse width are constant.

(5) The heating temperature control device according to any one of the configurations (1) to (4) is applied to an image forming apparatus, and an amorphous silicon photosensitive drum is used as the object.
It is applied to a heating roller for fixing.

(6) In the heating temperature control device having the above structure (5), a ceramic heater is used as a heating means for heating the heating roller.

[0016]

[Action]

(1) According to the heating temperature control device having the configuration (1) in the above means, in each of the plurality of heating devices, the heating means heats the object by energization, and the temperature detecting means detects the temperature of the object, The individual duty ratio control means controls the duty ratio of the heating means based on the temperature of the target object so that the target object reaches the target temperature and maintains the target temperature after reaching the target temperature. Controls the heating means.

At this time, the plurality of duty ratio detecting means detect the duty ratio of each heating means of the plurality of heating devices. Then, the duty ratio comparing means compares the duty ratios detected by the plurality of duty ratio detecting means with each other, and as a result, the comparing means discriminates the heating device having the latest rise in temperature. Further, the higher duty ratio control means controls the heating device so as to increase the duty ratio of the heating means of the heating device which is determined by the duty ratio comparison means to have the latest rise in temperature.

As described above, the higher duty ratio control means increases the duty ratio of the heating means of the heating device to increase the rising speed of the set temperature and shorten the time required for the rising of the temperature. As a result, the rise time of the temperature of the entire device can be shortened and the waiting time can be shortened.

(2) According to the heating temperature control device having the constitutions (2) to (4) in the above means, the pulse width of energization,
By changing the pulse period or the pulse amplitude height, the duty factor can be changed easily and surely, and the individual duty factor control means can smoothly perform the control.

(3) According to the heating temperature control device having the configuration (5) in the above means, the present invention can be applied to the heating temperature control of the amorphous silicon photosensitive drum of the image forming apparatus and the heating roller for fixing. Therefore, the start-up of the image forming apparatus can be speeded up and the waiting time until the image forming apparatus can be used can be shortened.

(4) According to the heating temperature control device having the configuration (6) in the above means, since the temperature rise time of the ceramic heater is short, the heating roller for fixing can reach the target temperature in a very short time. It is possible to shorten the rise time of the temperature of the controlled amorphous silicon photoconductor drum as compared with this, and contribute to the shortening of the rise time of the temperature of the entire apparatus.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 are views showing a first embodiment of a heating temperature control device according to the present invention.

FIG. 1 shows a heating temperature control device according to the present invention.
6 is a block diagram showing a configuration of a heating temperature control device, which is applied to a printer device using the a-Si photosensitive drum 11. FIG. The a-Si photosensitive drum 11 employs a method of heating the a-Si photosensitive drum 11 by a heater in order to prevent "image deletion" as described above. It is adapted to be heated by the drum heater 13 (heating means). As the drum heater 13, for example, a halogen heater is used.

When the drum heater 13 is energized, heat is generated to heat the a-Si photosensitive drum 11, and the drum heater 13 is energized by the drum heater energization rate control means 15 ( The individual energization rate control means) controls the energization amount per predetermined time to energize.

That is, the temperature of the a-Si photosensitive drum 11 heated by the drum heater 13 and increased in temperature is detected by the drum thermistor 17 (temperature detecting means), and the detected temperature is supplied to the drum heater. A signal is output to the rate control means 15.

Then, the energization rate control means 15 for the drum heater
Refers to the drum heater energization rate setting table recording unit 19 which stores a setting table as shown in FIG. 2, finds out the energization rate corresponding to the detected temperature from the drum thermistor 17, and based on the energization rate. The drum heater 13 is controlled so as to be energized.

As can be seen from the setting table of FIG. 2, the duty ratio is set so that the duty ratio is reduced as the temperature rises, whereby the overshoot that exceeds the target temperature can be prevented or suppressed. It is like this. As shown in FIG. 3, the energization rate is set so that the period L is constant, but the pulse widths are different from W1 and W2, respectively, so that the energization amount per predetermined time is different.

The above-mentioned drum heater 13, drum heater energization rate control means 15, drum thermistor 17, and drum heater energization rate setting table recording section 19 as a whole include a heating device 20 for the a-Si photosensitive drum 11. I am configuring.

The energization rate controlled by the drum heater energization rate control means 15 is detected by the drum heater energization rate sampling means 21 (energization rate detection means), and the detected energization rate is the energization rate comparison means. A signal is output to 23.

As shown in FIG. 4, the sampling operation at this time is time ΔT from the start of sampling (detection).
Sampling is performed for each time ΔT, and the energization time T1 is used for the first sampling, the energization time T2 is used for the second sampling, the energization time T3 is used for the third sampling, and the energization time T4 is used for the fourth sampling.
Sampling of the duty ratio is done one after another.

As described above, each sampling time ΔT has a length sufficiently larger than the pulse cycle L so that at least one pulse width (energization time T1 and the like) can be reliably detected. The total sampling time Ts is a variable, and this Ts increases by ΔT over time (Ts = Ts + ΔT).

Referring again to FIG. 1, the heating roller for fixing 31
A ceramic heater having a relatively fast rise time (several seconds to several tens of seconds) is used as the fixing heater 33 for heating the. When the fixing heater 33 is energized, the fixing heater 33 generates heat to heat the fixing heating roller 31, and the fixing heater 33 is energized by the fixing heater energization rate control means 3.
5 (individual energization rate control means) controls the energization amount per predetermined time to energize.

That is, the temperature of the fixing heating roller 31 heated by the fixing heater 33 and increased in temperature is detected by the fixing thermistor 37 (temperature detecting means), and the detected temperature is controlled by the fixing heater energization rate. Means 35
Signal is output to.

The fixing heater energization rate control means 35
Refers to the fixing heater energization rate setting table recording unit 39 that stores a setting table as shown in FIG. 5, and finds the energization rate from the temperature detected by the fixing thermistor 37.
The heater 33 is energized based on the energization rate.

This energization rate is set so as to decrease as the temperature rises, whereby it is possible to prevent or suppress overshoot that passes over the target temperature. Further, the duty ratio is the same as that of the heating device 20 shown in FIG. 3, the period L is constant, but the pulse width is W1,
The control is performed so that the amount of energization per a predetermined time is determined so as to be different from W2, that is, by changing the pulse width with a constant energizing pulse period.

The energization rate controlled by the fixing heater energization rate control means 35 is detected by the energization rate sampling means 41 (energization rate detection means), and the detected energization rate is output to the energization rate comparison means 23 as a signal. To be done. The sampling operation at this time is similar to that of the duty ratio sampling means 21 shown in FIG.
As described above.

The drum heater energization rate and the fixing heater energization rate input from the energization rate sampling means 21 and the energization rate sampling means 41 to the energization rate comparison means 23 are compared by the energization rate comparison means 23 to determine the energization rate. Comparison means 2
3 is that the rise of the temperature is delayed
And the fixing heater 33 are discriminated, and the result is output to the upper duty ratio control means 44 as a signal.

In order to judge which is slower in rising of temperature, it is judged by which one of the energization rates (pulse widths) is larger. That is, since the setting table is set so that the duty ratio decreases as the target temperature approaches, the higher the duty ratio, the farther from the target temperature. Therefore, it can be determined that the higher the duty ratio is, the later the rise of temperature is delayed.

The duty ratio comparing means 23 is used for the drum heater 1
When it is judged that 3 is delayed in rising of temperature,
Based on the signal, the upper duty ratio control means 44 outputs a signal to the drum heater duty ratio control means 15 to increase the duty ratio one step higher (one less number) on the setting table than the current duty ratio. The drum heater energization rate control means 15 controls the drum heater 13 so as to energize.

When the duty ratio comparing means 23 determines that the temperature rise of the fixing heater 33 is delayed, the higher duty ratio controlling means 44 causes the fixing heater duty ratio controlling means 35 to operate based on the signal. A signal is output, and the fixing heater 3 is applied to the fixing heater energization rate control means 35 so as to increase the energization rate one step higher on the setting table than the current energization rate.
Control 3

Next, the operation of such a heating temperature control device will be described with reference to the flowchart of FIG. When the power is turned on, sampling is not performed and the total Ts is 0.
(Step S1), the energization control of the drum heater 13 and the fixing heater 33 by the drum heater energization rate control unit 15 and the fixing heater energization rate control unit 35 is started. Such energization control is performed, and the energization rates of the drum heater 13 and the fixing heater 33 are repeatedly sampled by the energization rate sampling means 21 and 41 (step S2), and the following operation is performed for each sampling. Is done.

First, the drum heater 13 and the fixing heater 3
It is determined whether or not both or one of the three are not energized for being controlled by the drum heater energization rate control unit 15 or the fixing heater energization rate control unit 35 (step S3). Returns to before step S2 and repeats the same operation. If NO in step S3, it is then determined whether both the heater 13 for the drum and the heater 33 for fixing have the energization rate of 0 (step S4), and Y
In the case of ES, the process returns to the step before S2 and the same operation is repeated.

If NO in step S4, it means that both step S3 and step S4 do not apply, so that both the drum heater 13 and the fixing heater 33 have the drum heater energization rate control means 15 and the fixing heater energization. It means that the energization control is performed by the rate control unit 35, and the energization rates of both the drum heater 13 and the fixing heater 33 are not zero.

In this case, next, it is judged whether or not the energization rate of the fixing heater 33 is higher than the energization rate of the drum heater 13. If YES, the rise of the temperature of the fixing heating roller 31 is the a-Si exposure. It is determined that it is later than the body drum 11, and as described above, the upper duty ratio control means 44 outputs a signal to the fixing heater duty ratio control means 35 so that the current is higher than the current duty ratio set in the setting table. Energization control is performed by increasing the energization rate one step higher (step S
6).

If such control is not performed,
As shown in the graph R showing the rise of the temperature of the a-Si photosensitive drum 11 and the graph J showing the rise of the temperature of the fixing heating roller 31 as shown in FIG. 7, they are times t ₀ and t ₁ , respectively.
It is possible to change what has been started up with the change to a graph as shown in FIG. 8 by performing the above control.

That is, in FIG. 8, sampling S1
And the pulse widths are compared, and the fixing heating roller 31
Pulse width (J) is larger than the pulse width (R) of the a-Si photosensitive drum 11, the fixing heating roller 31 determines that the rise of the temperature is delayed, and the pulse width is set in the setting table. By increasing the current by one step and energizing, the current is lowered more steeply than in the case of FIG. 7 and the rising speed is increased. As a result, the rising time (J) of the fixing heating roller 31 is shortened to a time t ₃ (FIG. 8) shorter than t _{1 in} FIG.

Again in the flowchart of FIG. 6, if NO in step S5, the heater for drum 1
It is determined whether the energization rate of No. 3 and the energization rate of the fixing heater 33 are equal (step S7). If YES, the procedure returns to the step before step S2 and the same operation is repeated. In this case, it means that the rising times of both temperatures are the same and neither of them is delayed, so that neither of them needs to shorten the rising time and the control is continued as it is.

If NO in step S7, it means that the energization rate of the drum heater 13 is larger than the energization rate of the fixing heater 33, so that the rise of the temperature of the a-Si photosensitive drum 11 is the fixing. It is judged by the duty ratio comparing means 23 that it is behind the heating roller 31 for use, and this time, the higher duty ratio controlling means 44 outputs a signal to the drum heater duty ratio controlling means 15 to determine the current duty ratio defined in the setting table. Energization is controlled by increasing the energization rate one step higher than that.

That is, by performing sampling S2 in FIG. 8, since the pulse width (R) of the a-Si photosensitive drum 11 is larger than the pulse width (J) of the fixing heating roller 31 this time, a-Si is obtained. It is determined that the temperature rise of the photoconductor drum 11 is delayed, and the pulse width is increased by one step on the setting table to energize the photoconductor drum 11 so that the photoconductor drum 11 descends at a steeper slope than in the case of FIG. 7 to increase the rise speed. To go.

As a result, the rise time (R) of the temperature of the a-Si photosensitive drum 11 is shortened to the time t ₂ shorter than t _{0 in} FIG. 7, so that the rise time of the entire printer is t _0. It will be reduced to t ₂ from.

FIG. 9 is a diagram showing a second embodiment of the heating temperature control device according to the present invention. In the first embodiment, as shown in FIG. 3, the period L is the same and the pulse width is W.
While the duty ratio is changed by changing the pulse widths such as 1 and W2, in the second embodiment, as shown in FIG. 9, the pulse widths are all kept constant at W and the cycles are L1, L2 and L2.
By changing it as shown in No. 3, the energization rate is changed.

FIG. 10 is a diagram showing a third embodiment of the heating temperature control device according to the present invention. In the first embodiment, the pulse width is changed with a constant period, and in the second embodiment, the duty ratio is changed by changing the period with a constant pulse width. As shown in FIG. 10, the pulse width W and the period L are kept constant, and the pulse amplitude height is changed to H1, H2 to change the duty ratio.

In the above embodiment, the case where the present invention is applied to the two heating means in the printer has been described. However, it goes without saying that the present invention may be applied to an image forming apparatus other than the printer. The present invention can be applied to other devices other than the image forming device, and further, the present invention can be applied to a device having three or more heating means.

In the above embodiment, the energization rate of each heater is changed by changing the pulse width, the pulse period, or the pulse amplitude height. However, the energization amount per predetermined time can be changed. Any method may be used as long as it is.

[0055]

As described above, according to the present invention, the temperature set in the table is controlled by controlling the electric conductivity of the heating means of the heating device to be increased by one step from that set in the table. Increase the rising speed of
The time it takes for the temperature to rise can be shortened, and thus the rise time of the entire apparatus can be shortened and the waiting time can be shortened.

Further, since the present invention can be implemented by using a low power heater without using a high power heater,
It is possible to prevent the power consumption of the entire apparatus from increasing, and to prevent the electrostatic latent image from becoming unstable due to a large temperature change due to the overshoot, thereby performing reliable image formation.

Further, according to the first embodiment, the present invention can be applied to the heating temperature control of the amorphous silicon photosensitive drum of the image forming apparatus and the heating roller for fixing, whereby the temperature of the image forming apparatus can be controlled. It is possible to shorten the waiting time until the image forming apparatus becomes usable by speeding up the start-up.

According to the first embodiment, since the temperature rise time of the ceramic heater is short, the heating roller for fixing can reach the target temperature in a very short time.
In comparison with this, the rise time of the temperature of the controlled amorphous silicon photoconductor drum can also be shortened, which can contribute to the shortening of the rise time of the temperature of the entire apparatus.

Further, according to the first to third embodiments, by changing the pulse width, pulse period, or pulse amplitude height of energization, the energization rate can be changed easily and surely. The control by the individual duty factor control means can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing a first embodiment of a heating temperature control device according to the present invention.

FIG. 2 is a diagram showing a table in which a duty ratio of a drum heater 13 is set.

FIG. 3 is a waveform diagram showing a heater energization rate with a pulse width during energization, FIG. 3A is a waveform diagram showing an energization rate with a pulse width W1 with respect to a pulse period L, and FIG. FIG. 4 is a waveform diagram showing a duty ratio of W2 having a pulse width smaller than W1 of FIG.

FIG. 4 is a time chart during a sampling operation by a duty ratio sampling means.

FIG. 5 is a diagram showing a table in which the energization rate of a fixing heater 33 is set.

FIG. 6 is a flowchart showing an operation procedure of the embodiment of the heating temperature control device according to the present invention.

FIG. 7 is a-Si on the assumption that only the control operations by the drum heater energization rate control unit 15 and the fixing heater energization rate control unit 35 are performed and the upper energization rate control unit 44 does not perform the control operation. FIG. 6 is a diagram showing a graph R showing the rising state of the photosensitive drum 11 and a graph J showing the rising state of the fixing heating roller 31.

FIG. 8 is a higher-order energization rate control unit 44 together with a drum heater energization rate control unit 15 and a fixing heater energization rate control unit 35.
FIG. 7 is a diagram showing a graph R showing a rising state of the a-Si photosensitive drum 11 and a graph J showing a rising state of the fixing heating roller 31 in the embodiment of the present invention in which the control operation is also performed.

FIG. 9 is a pulse waveform diagram showing a duty ratio of a heater according to a second embodiment of the heating temperature control device of the present invention.
(A) is a pulse waveform diagram of cycle L1, and FIG. 9 (b) is cycle L
2 is a pulse waveform diagram, and FIG. 9C is a pulse waveform diagram of period L3.

FIG. 10 is a pulse waveform diagram showing a duty ratio of a heater according to a third embodiment of the heating temperature control device of the present invention, and FIG.
0 (a) is a pulse waveform chart of pulse amplitude height H1, FIG.
(B) is a pulse waveform diagram of a pulse amplitude height H2.

[Explanation of symbols]

 11 a-Si Photosensitive Drum 13 Drum Heater 15 Drum Heater Duty Rate Control Means 17 Drum Thermistor 19 Drum Heater Duty Rate Setting Table Recording Unit 20, 40 Heating Device 21 Drum Heater Duty Rate Sampling Means 23 Duty Rate Comparison Means 31 Fixing heating roller 33 Fixing heater 35 Fixing heater energization rate control means 37 Fixing thermistor 39 Fixing heater energization rate setting table recording section 41 Fixing heater energization rate sampling means 44 Higher rate energization control means

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 15/20 109 21/20 H05B 3/00 310 D

Claims (3)

[Claims] 1. A heating means for heating an object by energization, a temperature detecting means for detecting the temperature of the object, and an individual duty ratio control means for controlling the duty ratio of the heating means based on the detected temperature. A plurality of heating devices having, a plurality of duty ratio detecting means for detecting the duty ratio of each heating means of the plurality of heating devices, and comparing the respective duty ratios detected by the plurality of duty ratio detecting means The duty ratio comparing means for determining the heating device having the slowest rise in temperature, and the heating so as to increase the duty ratio of the heating means of the heating device for which the duty ratio comparing means determines the slowest rise in temperature. A heating temperature control device comprising: a high-order conductivity control means for controlling the device; 2. The heating according to claim 1, wherein the heating temperature control device is applied to an image forming apparatus, and the object is applied to an amorphous silicon photosensitive drum and a heating roller for fixing. Temperature control device. 3. A ceramic heater is used as a heating means for heating the heating roller.
The heating temperature control device according to.