JPS60121480A - Heat fixing device - Google Patents

Abstract

PURPOSE:To perform high-speed copying or the like without increasing the rated power consumption by detecting the temperature of the surface of a fixing device, which heats a powdery material on a base material to fuse and fix it, or its fluctuating factor to control the quantity of the base material which passes the fixing device in a unit time. CONSTITUTION:The image of a back and forth moved original 2 is developed by a developing device 5 and is transferred to a transfer paper 7 and is allowed to pass fixing rolls 13 and 14. A power source voltage is supplied to a transformer 21 for a voltage detecting circuit and a transformer 22 for a control circuit. The output voltage of the transformer 21 is compared with a voltage between both ends of a variable resistance 25, and a voltage detector A outputs a voltage detection signal. The output of the transformer 22 is supplied to a going motor control circuit 31 and a control circuit 32 through a DC stabilizing circuit 30. The variable resistance 25 is so set that the power source voltage is detected when it becomes 95% of a rated voltage, and a fixing heater 15 of the roll 13 is controlled to turn on and off by a load 34 connected to the circuit 32. Thus, high-speed copying is possible till the power source voltage is reduced to 95%, and the copying speed is made lower for <=95% reduction, and constant fixing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a heat fixing device used in copying machines and the like, which melts and fixes powder on a base material by heating the powder on the base material.

<Prior art and its drawbacks> Electrophotographic copying machines, which most commonly use a heat fixing device, are now installed in many offices, etc., but due to the demand for higher speed, the power consumption has increased. A problem has arisen. That is, as the speed of copying machines increases, there is a possibility that the increased power consumption of the heat fixing device will exceed the 15A power capacity of the most common power outlet standard. If we simply increase the capacity of the fixing device without taking any measures, most high-speed machines will probably not be able to be used with a regular power outlet, and special power supply work will be required at the same time as the copier is installed. It will be done. However, performing special power supply work to install a copying machine means that there will be costs for the power supply work in addition to the price of the copying machine, and the actual price paid by the user will be the sum of these two costs. This has the disadvantage of significantly increasing costs. Also, when setting the fixing device, it is usually necessary to take into account fluctuations in the power supply voltage so that sufficient fixing can be achieved at the worst time, that is, when the voltage is 90% of the rated voltage, but for high-speed machines If the lever design method is simply applied, at the rated voltage, more than enough power will be supplied to the fixing device, that is, more power than necessary including wasted power will be supplied, which will reduce the overall rating of the copier. This would increase power consumption and would limit the capability (high speed) of the copier if it were to be compatible with a regular power outlet.

<Object of the Invention> An object of the invention is to provide a heat fixing device that can be used as a faster copying machine without increasing the rated power consumption.

<Structure and Effects of the Invention> The present invention provides a method for fixing bases that pass through the fixing device when the power supplied to the fixing device decreases and the amount of heat emitted from the fixing device becomes unbalanced. This was done by focusing on the fact that the balance between the two can be maintained by reducing the amount of material used, and it is equipped with a detector that detects the surface temperature of the fuser or its fluctuation factors, and a unit time according to the output of the detector. means for controlling the quantity of substrates passing through the fuser within the fuser, the power supplied to the fuser by the detector and the power emitted from the fuser to the substrate. A level at which the amount of heat can be balanced is determined, and the number of substrates passing through the fixing device within a unit time is controlled in accordance with that level.

According to the present invention, with the above-mentioned configuration, there is no need to design a device to obtain a constant fixing performance under the worst conditions, for example, under conditions where the voltage is reduced to 90% of the rated voltage, as in the conventional case. When external conditions are added that cause the surface temperature of the fuser to drop, such as a drop in voltage, the number of substrates passing through the fuser can be suppressed to ensure that the surface temperature does not drop. A certain level of fixability can be obtained. Therefore, unlike in the past, there is no extra power consumption at the rated time, and when external conditions such as a drop in voltage change, the amount of substrates passing through the fuser is reduced; High speed performance can be achieved without increasing the rated power consumption of the fixing device.

<Embodiment> FIG. 1 is a block diagram of a copying machine to which a heat fixing device according to an embodiment of the present invention is applied. In the figure, reference numeral 1 denotes a document table that carries the document table 2 and moves back and forth; 3, a photoconductor drum that rotates clockwise; 4, a charger that uniformly charges the surface of the photoconductor; 5, a developer; and 6 8 is a cleaner, 9 is an exposure lamp, 10 is a plastic fiber lens that exposes the surface of the photoreceptor to the light reflected from the original 2, and 11 is a transfer device that transfers the image formed on the photoreceptor onto the transfer paper 7; Reference numeral 12 indicates a cassette that accommodates the transfer paper 7, and a paper feed roller 12 that conveys the transfer paper one by one from the cassette I/11. Further, 13 and 14 are fixing rollers, and a heater 15 is disposed inside the fixing roller 13. With the above configuration, when the copy button is pressed, the document table 1 moves to the left, and at the same time, the photoreceptor drum 3 rotates, and the document 2 is exposed on the photoreceptor and made into a visible image by the developer 5. The image is transferred to transfer paper 7, which further passes through fixing rollers 13 and 14 and is ejected. When the document table 1 completes its forward movement, a switch (not shown) detects this and causes the document table 1 to perform a backward movement. Then, one copy is completed when the document table 1 returns to the home position. During multi-copying, the following two operations are continuously repeated to feed the transfer paper 7 to the fixing rollers 13, 14 at regular intervals.

FIG. 2 is a circuit diagram of the control section of the copying machine.

The power supply voltage supplied from the power outlet 20 is supplied to the primary sides of the voltage detection circuit transformer 21 and the control circuit transformer 22. The turns ratio is set so that the secondary voltage of the transformer 21 is rated 8■, and the full-wave rectifier 23
join. The capacitor 24 smoothes the full-wave rectified voltage to convert the secondary side voltage 8cm into a DC voltage of approximately 10V. The smoothed voltage is divided by a variable resistor 25 and a resistor 26,
The divided voltage is applied to the gate of transistor 27. A Zener diode 28 that forms a reference voltage is connected to the emitter of the transistor 27, and the transistor 27 is turned on by comparing the sum of the Zener voltage 5 and the base-emitter voltage of the transistor 27 with the voltage across the variable resistor 25. , you're trying to control it off. Transistor 29 receives the output of transistor 27, turns on and off in response to on and off of transistor 27, and outputs power supply voltage detection signal a. With the above configuration, the variable resistor 25. Resistance 26. A circuit combined with transistors 27 and 29 and Zener diode 28 constitutes voltage detector A that detects fluctuations in power supply voltage.

The secondary output of the transformer 22 is stabilized by a DC stabilizing circuit 30, and is stabilized by a double-acting motor control circuit 31 and a control circuit 3.
2. The double-acting motor control circuit 31 controls the speed of the double-acting motor 33 in response to the output of the output transistor 29 of the voltage detector 1. The control circuit 30 also controls the double-acting motor control circuit 31 and the solenoid 9, as well as loads 34 such as relays, clutches, and motors.

The power supply voltage obtained from the power outlet 20 is further supplied to the fuser heater 15 via a relay contact 35 and to the exposure lamp 37 via a relay contact 36 . Relay contacts 35 and 36 are included in the load 34 and are turned on by the control circuit 32.

Controlled off.

The fuser heater 5 has a rating of 900W. Generally, in a high-speed copying machine with a copying speed of 30 sheets per minute, a certain level of fixing performance cannot be obtained unless 800 W of power is continuously supplied to the fuser heater. Therefore, by using a fuser heater 5 with a rating of 900 W, a margin of 100 W can be provided.Next, the setting position of the variable resistor 25 of the voltage detector will be explained. If a 900 W heater is used as the fuser heater 15 as described above, the T-degree heater output will be 800 W when the power supply drops to 95% of the rating. Therefore, at a voltage of 95% to the rated voltage, sufficient fixing performance can be obtained at a copying speed of 30 sheets per minute. On the other hand, if the power supply voltage drops to 90% of the rating, which is the worst condition of the power supply, the heater output will be approximately 700W. Therefore, in this case, the copying speed may be reduced to such an extent that the surface temperature of the fixing device does not drop during continuous copying. According to experiments, when the power supply voltage is rated at 90% of the rated value, sufficient fixing performance can be obtained by setting the copying speed to 25 sheets per minute. Therefore, when using a fuser heater with a rating of 900W, copying should be possible at a high copying speed of 30 sheets per minute until the power supply voltage drops to 95%, and when the power supply voltage drops to 95% or less, By lowering the copying speed to 25 sheets per minute, constant fixing performance can be obtained regardless of the amount of variation in the power supply voltage. Therefore, the variable resistor 25 of the voltage detector is set to detect when the power supply voltage reaches 95% of its rating.

The setting position of the variable resistor 25 will be explained in more detail.

As mentioned above, the voltage across the capacitor 24 is IOV at the rated power supply voltage. Therefore, when the power supply voltage drops to 95% of the rating, the voltage across the capacitor 24 will be 9.5%.
It drops to 5v. On the other hand, the Zener diode 28 is selected to have a Zener voltage of 5V. Therefore, the setting position of the variable resistor 25 is set to 5,5 which is the sum of the Zener voltage 5 and the voltage between the terminals of the transistor 27 and 0.65 V when the voltage across the capacitor 24 is 9.5 V. ■ If you set it so that the power supply voltage is 95
% or less, the transistor 27 remains off, and when it exceeds 95%, it turns on. In other words, the power supply voltage detection signal a becomes "■]' when the power supply voltage is 95% or less of the rated value, and becomes "L" when it exceeds 95%.
becomes.

By setting the variable resistor 25 as described above, the double-acting motor control circuit 3I can control the speed of the double-acting motor 33 at 95% of the rated power supply voltage. That is, when the power supply voltage detection signal a is "H", the double-acting motor control circuit 31 lowers the rotation speed of the double-acting motor 33 to set the copying speed to 25 copies per minute. Also, the power supply voltage detection signal a is
When the copying speed is "L", the rotational speed of the double-acting motor 33 is increased to a copying speed of 30 sheets per minute.

As described above, the voltage detector A detects fluctuations in the power supply voltage applied to the fuser heater, that is, the cause of fluctuations in the surface temperature of the fixing roller 13. In this state, high-speed performance of 30 sheets per minute can be achieved, and within this range, the excess power consumed by the fuser heater 15 is not so large, so the power consumption of the fuser does not need to be increased that much. A copying machine capable of exhibiting high-speed performance with a normal power supply voltage can be obtained.

Next, the double-acting motor control circuit 31 will be explained with reference to FIG. This figure is a circuit diagram of the double-acting motor control circuit 3.

In the figure, a reference signal generation circuit 310 generates a constant reference pulse and inputs it to a frequency divider 311 and a frequency divider 312 having a smaller frequency division ratio. The AND gate 313 logically ANDs the power supply voltage detection signal a and the output of the frequency divider 311, and the AND gate 3]4 logically combines the signal obtained by inverting the power supply voltage detection signal a by the inverter 315 and the output of the frequency divider 312. Multiply. OR game 1-3] 6 is'' - AND game 1-31
3. Log the output of 31.4, AND game 1-317
The logical sum output and the backward motion permission signal 2 from the control circuit 32 are ANDed and outputted to the motor drive circuit 318.

Further, the output of the motor drive circuit 318 is supplied to the double-acting motor 33.

With the above configuration, when the power supply voltage detection signal a is "L", the output of the frequency divider 312 is guided to the motor drive circuit 318, and when the power supply voltage detection signal a is "H", the output of the frequency divider 311 is guided to the motor drive circuit 318.Since the frequency divider 311 has a higher frequency division ratio than the frequency divider 312,
After all, the frequency of the divided pulse guided to the motor drive circuit 318 is smaller when the power supply voltage detection signal a is "'H" than when it is "I7".In other words, the double-acting motor 33 detects the power supply voltage. The rotational speed is made faster when signal a is "I" than when signal a is "H". As a result, when the power supply voltage exceeds 95% of the rated value, the backward movement speed of the document table j is fast, and when it falls below 95%, the backward movement speed becomes relatively slow. Therefore, by appropriately setting the frequency division ratio of the frequency dividers 311 and 312, when the power supply voltage exceeds 95% of the rated value, the document table 1 is moved back so that the copying speed is 30 sheets per minute. Furthermore, when the power supply voltage becomes 95% or less of the rated value, the document table 1 can be moved back so as to achieve a copying speed of 25 sheets per minute.

In the above embodiment, the rotation speed of the double-acting motor 33 was controlled based on 95% of the rated power supply voltage, but the reference was set to two levels, 94% and 97% of the rated value, and the The backward movement speed of the document table 1 by the moving motor 33 can be set in three stages. 4 and 5 are circuit diagrams of the voltage detector B and the double-acting motor control circuit 32 in that case. In the configuration, the difference from the first embodiment is that the voltage detectors B are arranged in two stages in parallel, and the variable resistor 2 in the first stage is
5 is set to 94% of the rating, and variable resistor 25' is set to 97% of the rating. Furthermore, the output of the first-stage output transistor 29 and the output of the second-stage output transistor 29' are received by a combination circuit of AND gates 50 to 52 and an inverter 53 to determine three states. A frequency-divided pulse from one of the frequency dividers 321 to 323 is guided to a motor drive circuit 329. With this configuration 4, the first stage output transistor 29 of voltage detector B
and the output of the second stage output transistor 29' are "
l(", when the voltage is "H", the power supply voltage detection means C becomes "H", and similarly the output of each transistor becomes "H").
, when the output of each transistor is "L", the signal d becomes "■]", and when the output of each transistor is "L", "L", the signal e becomes "I]". Therefore, when the power supply voltage is 94% or less of the rating, The frequency divider 321 with the largest frequency division ratio is selected, and the power supply voltage is 94% to 97% of the rated value.
When the frequency is between the two, the frequency divider 322 is selected, and when the power supply voltage is 97% or more of the rated value, the frequency divider 323 with the smallest frequency division ratio is selected.

The backward movement speed of the document table 1 can be controlled as described above by detecting a drop in the power supply voltage, which is the main factor of variation in the surface temperature of the fixing roller 13.
Factors for variation in the surface temperature (3) include variations in the power supply voltage as well as variations in the ambient temperature (1) and ambient humidity. For example, if the ambient temperature is low, the temperature of the transfer paper itself is also low, so the amount of heat absorbed by the paper increases when it passes the fixing roller. Therefore, maintaining the fixing surface at a constant temperature requires more power than when the ambient temperature is high. The same can be said about humidity. When the humidity is high, the amount of water contained in the transfer paper increases, which increases the amount of heat absorbed by the paper, requiring more power than when the humidity is low.

FIG. 6 is a circuit diagram of a temperature detector that controls the double-movement speed of the double-movement motor 32 in accordance with fluctuations in ambient temperature, using fluctuations in ambient temperature as a factor for fluctuations in the surface temperature of the fixing roller. The difference in configuration from the voltage detector shown in FIG. 2 is that a thermistor 00 whose resistance value decreases as the temperature rises is connected instead of the resistor 26. With this configuration, if the variable resistor 25 is set so that the output transistor 29 turns on when the desired ambient temperature is reached, the temperature detection signal a' becomes "L" when the ambient temperature exceeds the set temperature.
, if the temperature is below the set temperature, it becomes H''.If this signal is output to the double-acting motor control circuit 31 shown in FIG. 2, the copying speed can be changed depending on whether the ambient temperature is above or below the set temperature. As shown in the figure, by using a multi-stage configuration of two or more stages, it is easy to make the copying speed multi-stage.

If a humidity detection sensor is connected in place of the thermistor 100, the copying speed can be changed even in response to changes in humidity using the same circuit configuration as above. Furthermore, as shown in FIG.
If the circuit shown in the figure is connected to a power supply circuit as shown in FIG. 2, it is possible to simultaneously detect fluctuations in power supply voltage and temperature, and change the copying speed in accordance with these fluctuations. 8th
The figure shows an example of an experiment using the circuit shown in FIG. In the figure, the numbers in the table represent the number of copies per minute.

In the embodiments described above, the number of transfer sheets passing through the fixing roller within a unit time, that is, the copying speed, was controlled by controlling the backward movement speed of the document table; however, in an optical mobile copying machine, What is necessary is to control the return speed of the optical system. In addition, instead of controlling the backward movement speed of these document scanning systems, the forward movement speed, or both the forward movement and backward movement speeds may be controlled, or even the forward movement to the backward movement may be controlled. The time during which the document table and optical document scanning system are stopped may be controlled when moving, or the time during which the document table is stopped when moving from backward movement to forward movement may be controlled. Further, as another method of controlling the amount of transfer paper passing through the fixing roller within a unit time, the actual passing speed of the transfer paper may be controlled. In other words, if the surface temperature of the fixing roller is about to drop due to a drop in the power supply voltage, etc., if you change the conveyance speed to slow down the speed at which the transfer paper passes through the fixing roller, the fixing roller will be removed within a unit time. The amount of transfer paper passing through is reduced, and a certain level of fixing performance can be obtained. As a method of changing the number of transfer sheets passing through the fixing roller within a unit time, in addition to changing the conveying speed of the conveying system as described above, it is also possible to change the rotation speed of the fixing roller.

Further, in the above embodiment, a voltage detector is used as a detector for detecting a factor of variation in the surface temperature of the fixing roller.

Although a temperature detector, a humidity detector, etc. are used, a detector that directly detects the surface temperature of the fixing roller may also be used. In other words, the surface temperature of the fixing roller is directly detected,
If the copying speed is controlled so that the surface temperature is constant, it is possible to obtain constant fixing performance even if fluctuations in the power supply voltage occur. Further, as another method for detecting fluctuations in the surface temperature of the fixing roller, the continuous power supply time to the heater inside the fixing roller may be detected. In this case, if the continuous power supply time to the heater is long, it means that the temperature on the surface of the fixing roller is about to drop, so the copying speed can be controlled by determining whether the continuous power supply time continues for a certain period of time or more. become.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an electrophotographic copying machine using a heat fixing device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of the control section of the copying machine, FIG. 3 is a circuit diagram of the double-acting motor control circuit, and FIG. 4 shows another example of the voltage detector of the control section. The figure shows another example of the above-mentioned rear motor control circuit. Furthermore, FIG. 6 is a circuit diagram of a temperature detector, and FIG. 7 is a circuit diagram of a temperature and voltage detector. Further, FIG. 8 is a diagram showing an example of controlling the copying speed when the circuit shown in FIG. 7 is used. 13.14 Fixed roller, 15-heater, A, B-voltage detector. Applicant Sharp Co., Ltd. Agent Patent Attorney Hisao Komori0

Claims (1)

[Scope of Claims] (11) A fixing device that heats the powder of the base material (2) to fuse and fix the powder to the base material (2), and detects the surface temperature of the fixing device or its fluctuation factors. A heat fixing device comprising: a detector for detecting a heat-fixing device; and means for controlling the number of base materials passing through the fixing device within a unit time according to the direction of output of the detector. (2) The detector. is the voltage that detects fluctuations in the power supply voltage.
The heat fixing device according to claim 1, which is a pressure detector. (3) The heat fixing device according to claim 1, wherein the detector is a temperature detector that detects fluctuations in ambient temperature. (4) The heat fixing device according to claim 1, wherein the detector is a humidity detector that detects fluctuations in ambient humidity. (5) A patent claim in which the detector comprises at least two of a voltage detector for detecting fluctuations in power supply voltage, a temperature detector for detecting fluctuations in ambient temperature, and a humidity detector for detecting fluctuations in ambient humidity. The heat fixing device according to item 1. (6) The heat fixing bag W6 according to claim 1, wherein the detector is a surface temperature detector that detects the surface temperature of the fixing device. (7) The detector continuously supplies power to the fixing device. The heat fixing device according to claim 1, which detects time.