JP2764105B2 - Abnormal state detection method in controlled device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a motor for controlling the temperature of a fixing device incorporated in a laser printer or other electrophotographic apparatus, and changing the elevation speed of a bin incorporated in a sorter in a plurality of stages. Abnormal state in the controlled device, such as controlling the rotation speed of the controlled device, which varies the temperature, the rotation speed, and other physical outputs of the controlled device over time based on a predetermined request signal and shifts to a desired set value Related to the detection method.

2. Description of the Related Art Conventionally, a heating element built in a heating roller is energized after power is turned on, such as a thermal fixing device including a heating roller and a pressure roller incorporated in an electrophotographic apparatus, so that toner is first softened. After the temperature is shifted to a first set temperature higher than the temperature, the heat generating element is maintained at the first set temperature by on / off control or time proportional control. The heating roller is heated and the temperature is shifted to a second set temperature at which fixing can be performed. After the temperature is maintained during the printing operation, the roller pair is rotated again without heating the heating roller by the print end command again. There is a temperature control method that shifts to a set temperature of 1 and repeats such temperature control.

A circuit configuration in such a temperature control method generally includes a reference voltage generation circuit corresponding to the first and second set temperatures, and a comparator for comparing the reference voltage with a detection voltage corresponding to a surface temperature of the heating roller. And a timer corresponding to the set temperature number, and a timer is attached to the comparator to detect the heating element and other abnormal conditions, and the detected voltage is set to a reference voltage within a time determined by the timer. It is determined whether or not the above condition is reached, and if the output from the comparator is not turned on or off even after the set time has elapsed, it is often displayed as abnormal.

"Problems to be Solved by the Invention" However, for example, when heating from room temperature to a first set temperature of about 150 ° C., the timer must be set in consideration of fluctuations in room temperature and other environmental fluctuations. Inevitably, the abnormality detection determination is inevitably slow, and it is often the case that an abnormality is determined to be normal.

For this reason, there is a circuit in which a correction circuit corresponding to the room temperature and other environmental parameters is added to the control circuit. However, such a configuration has a problem that the control circuit is easily complicated.

In addition, the set time must be set by adding a margin time to a normal time for heating from room temperature to 150 ° C., which means that the heating element is energized for a long time even if there is an abnormality. That could mean a serious secondary disaster. The same problem occurs when the temperature shifts from the first set temperature to the second set temperature and from the second set temperature to the first set temperature.

In order to solve such a defect, a reference voltage corresponding to fourth and fifth intermediate detection temperatures for detecting an abnormality between the room temperature and the first set temperature and between the first set temperature and the second set temperature. It is conceivable to perform the abnormality detection by setting the following. However, if such a configuration is adopted, a large number of reference voltage generation circuits, switching circuits, comparators, and the like are required, and as a result, the circuit configuration is further complicated.

In view of the drawbacks of the prior art, the present invention is an intermediate transition process in which the temperature and other physical output values output from the controlled device are shifted to a predetermined set value accurately and reliably with a simple circuit configuration. It is an object of the present invention to provide a method for detecting an abnormal state in a region.

"Means for Solving the Problems" The present invention proposes an abnormal state detecting method including the following AB and A'-C as shown in FIG. 5 in order to achieve such a technical problem.

A, for example, when shifting the physical output of the controlled device to a steady set value, the detection voltage S1 ~ corresponding to the physical output value
If S4 does not reach a predetermined reference voltage (hereinafter referred to as a first reference voltage V1) located in an intermediate process area until the physical output on the controlled device side reaches a steady set value, B Perform the abnormality detection as described. (This step is the first
A ', and even when the detection voltages S1 to S4 reach the first reference voltage V1, there are cases where the temperature rises normally and where the temperature rises abnormally. It is necessary to perform abnormality detection again. (This step is referred to as a first abnormality detection.) The case where the detection voltages S3 and S4 have not reached the first reference voltage V1 means that the detection voltages S3 and S4 are in the case of a physical output value increasing step. Becomes lower than or equal to the first reference voltage V1, and in the case of the descending step, the detection voltages S3 and S4
Of the reference voltage V1 or more.

B, and when the detection voltages S3 and S4 do not reach the first reference voltage V1, the reference voltage output from the variable reference voltage generating means is changed to a predetermined voltage change pattern P1 based on environmental factors. In the direction approaching the detection voltages S3 and S4, and the detection voltages S3 and S4 are reduced within the time T set by the timer means.
V2) is determined by a comparator. If the detection voltages S1 to S4 have not yet reached the relaxed reference voltage, it is determined that an abnormality has occurred (this process is referred to as second abnormality detection). .

In this case, the time T set by the timer means does not necessarily indicate a fixed time, but may be set to a time taking into consideration the environmental temperature as shown in an embodiment described later.

C, on the other hand, the detection voltages S1, S
2 has reached the first reference voltage V1, the reference voltage V1 is relaxed in a direction exceeding the detection voltages S1 and S2 based on a voltage change pattern P1 determined in advance based on environmental factors, The presence or absence of an abnormality is detected by comparing and determining whether the detection voltages S1 and S2 reach the relaxed reference voltage (hereinafter, referred to as a third reference voltage V3). In this case, the predetermined voltage change pattern P1 based on the environmental factor may be selected by detecting the external environmental temperature at the start of the temperature rise. The selection may be made using the temperature gradient immediately after the start of the rise.

In general, the burnout abnormality often occurs when the heater or the sensor is heated to a certain level after a predetermined temperature rise.
Therefore, it is possible to make a selection using the temperature gradient immediately after the start of the temperature rise.

[Operation] According to the technical means, an abnormal state can be detected early in the intermediate process area until the steady set value is reached, so that the abnormal state can be detected early, and a serious secondary disaster may occur. Can be avoided.

Also, when the detection voltages S1 to S4 do not reach the predetermined reference voltage V1 located in the intermediate process area, the detection voltages S1 to S4 are not uniformly determined to be abnormal, and even when the detection voltages S1 to S4 reach the reference voltage V1, the variable reference voltage generation means is provided. The second and third reference voltages V2 and V3 output from the detection voltages S1 to S4 based on a predetermined voltage change pattern P1 set in consideration of environmental factors.
In order to alleviate the abnormality toward the side, it is possible to detect an abnormal state in consideration of environmental fluctuation factors, and it is possible to avoid the possibility of erroneously determining the normal state as abnormal.

Further, the present invention provides a reference voltage generating means capable of arbitrarily setting a reference voltage without requiring a large number of reference voltage generating circuits, switching circuits, comparators, etc., and a detection voltage corresponding to a physical output.
The circuit configuration can be simplified because it can be configured by a detection unit that outputs S1 to S4, a comparator, and a timer unit that can arbitrarily change the set time.

Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

1 to 6 show a temperature control device of a heat fixing device according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a heat fixing device applied to the present invention.
A heating / fixing roller 2 having a built-in heating element 1 and driven and rotated in a direction indicated by an arrow by a drive system (not shown); a pressure roller 3 which is driven by the roller 2 and has no heating means; 2 has a temperature detecting element 4 composed of a thermistor for measuring the surface temperature.

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

Reference numeral 5 denotes a reference voltage generator including a DA converter and the like, and outputs a reference voltage arbitrarily set based on a reference voltage generation pattern Pn read from a storage means 6 described later.

The comparator 7 is a reference voltage output from the reference voltage generator 5
By inputting Vn and a detection voltage corresponding to the surface temperature of the fixing roller 2 formed by the temperature detection element 4 and the resistor R1, a control signal having a pulse width corresponding to a conduction width proportional to the surface temperature is compared. To the device control circuit 8.

The comparator control circuit 8 sends the on / off output generated based on the control signal to a solid state relay SSR (not shown) to control the power supply to the heating element 1 while heating, lowering the temperature of the fixing roller 2 or keeping it at a constant temperature. Perform temperature control to maintain.

Reference numeral 10 denotes a control circuit which selects a desired pattern Pn and its parameters from the plurality of reference voltage generation patterns Pn read into the storage means 6 and inputs the waveform parameters to the reference voltage generator 5, and is generally constituted by a microcomputer. I have.

The configuration will be described with reference to FIG. 2. Reference numeral 6 denotes a storage means formed of a read-only memory for measuring a plurality of reference voltage generation patterns Pn and a heating rate or a cooling rate for setting the waveform. The reference voltage corresponding to the detection point serving as the reference is input.

Reference numeral 19 denotes a control unit comprising a CPU, which outputs various command signals via a command register 18 based on a start signal or a comparison output from the comparator 7 and the like, to an oscillator / control circuit 20 and a timer 1.
5. In addition, according to an operation procedure described later while transmitting to the reference voltage generator 5 and the like, one of the reference voltage data groups stored in the storage means 6 is selected based on an address set in each register described later. Alternatively, control is performed to appropriately transmit a plurality of reference voltage data to the reference voltage generator 5, or after an abnormality is detected by an operation procedure described later, an error signal is output in the case of an abnormality, and an oscillator is controlled in the case of a normal operation. The circuit 20 is restarted and predetermined temperature control is performed.

Reference numerals 11 to 14 denote various registers for designating predetermined addresses at which reference voltage data to be read out to the storage means 6 based on a signal from the command register 18 are stored. For example, FIG. As shown in (1), when shifting from room temperature to printing temperature (100), and when shifting from weight temperature to printing temperature (011)
The addresses corresponding to various reference voltage generation patterns Pn such as are stored, and have an address arrangement as shown in FIG. 7C via the pattern selection control circuit 21 based on a signal from the control unit 19. The corresponding address is set in the storage means 6 side.

As shown in FIG. 7 (b), the parameter identification register 12 stores an address for setting the step position of the pattern Pn at which the temperature control is to be started based on the detection voltage from the temperature detection element 4. . The step counter 13 includes the pattern selection register 11 and the parameter identification register.
Reference voltage generation pattern as shown in FIG. 6 based on 12
After selecting P1 and P2, after the temperature of the heat fixing roller 2 reaches a predetermined temperature based on the detection voltage from the temperature detection element 4, a counter for selecting the next step, or a PWM basic unit counter 14 Is a counter for counting the ON / OFF width of each step in a time-coefficient manner. The counters 13 and 14 control the heating element 1 based on a control signal from the oscillator / control circuit 20.
It is possible to set various counter values for generating a pulse signal for performing the energization control, and thereby it is possible to perform proportional control based on the pattern Pn.

Reference numeral 15 denotes a timer that counts a change speed when passing between the detection points, and 16 denotes a timer setting register that sets an initial value corresponding to a set time to the timer 15, and the timer 15 is supplied to the timer 15 by a setting signal from the register 16. Initial value is set.

The timer 15 counts while the output of the comparator 7 is off, and when the count value of the timer 15 becomes equal to or more than the full count, the timer flag is turned on, and the control unit 19 determines that this is abnormal, and performs heating or Stop the cooling operation. Also the timer
If the count value of 15 is within the full count, the control unit 19 determines that this is normal, and sets a predetermined number of upper bits of the count value in the parameter identification register 12.

Next, the operation of the present invention based on such a configuration will be described based on the flowchart shown in FIG.

First, as shown in FIG. 3 (a), when the temperature of the fixing roller side is heated from room temperature, the operation of the control unit 19 determines which heating step is from room temperature to print temperature or weight temperature. Judging from the sequence, an address corresponding to the corresponding reference voltage generation pattern P1 is set in the pattern selection register 11. That is, the reference voltage generation pattern P1 is selected. (STEP 1) After selecting a predetermined parameter from the parameter identification register 12 based on the detection voltage from the temperature detection element 4, that is, after setting the step position of the pattern P1 at which temperature control should be started, the heating element The energization control of 1 is started. (STEP 2) And the detected voltage corresponding to the actual temperature of the fixing roller 2
S1 to S4 are control start points located in the middle of the heating temperature process
It is confirmed whether or not the heating element 1 has passed (STEP 3), and if it has not passed within a predetermined time, it is determined that the heating element 1 is disconnected. (ST
EP 4) After passing the control start point 10, the first reference voltage V1 corresponding to the first detection reference temperature 11 is read from the storage means 6 based on the reference voltage generation pattern P1, and the reference voltage generator 5 (STEP 5), and after a lapse of a predetermined time, the reference voltage V1 is transmitted from the generator 5 to the comparator 7, and the detection voltages S3 and S4 on the fixing roller 2 side are lower than the first reference voltage V1. Then, the process proceeds to a second abnormal state detection step (hereinafter referred to as error check 2). (STEP 6) On the other hand, when the detection voltages S1 and S2 on the fixing roller 2 side are equal to or higher than the first reference voltage V1, the process proceeds to a third abnormal state detection step (hereinafter referred to as error check 3). (STEP 7) Then, after the two error checks 2 and 3 determine that the operation is normal, the process proceeds to a predetermined proportional control operation, and as shown in FIG. 6, the detected voltage is set in each step based on the reference voltage generation pattern P1. The predetermined proportional control is performed while selecting the next step every time the temperature reaches the corresponding predetermined temperature. (STEP 8) On the other hand, as shown in FIGS. 3 (b) and 5, the error check 2 process saves the first reference voltage V1 as a target value and stores it as a target value (STEP 11). The current state is held as an ON output during the heating step and an OFF output during the cooling step. (STEP 12) Next, it is determined whether the step is a temperature lowering step, that is, whether the first reference voltage V1 is to be set up or down (STEP 13). Based on the generation pattern P1, the reference voltage (hereinafter referred to as the second reference voltage V2) is set to decrease in a direction approaching the detection voltages S3 and S4 (STE
P14 For example, the reference voltage in the preceding step may be set, or another reference voltage generation pattern Pm for error checking is provided, in which the second reference voltage V2 is set.
May be set. In addition, during a normal operation, the timer setting register 16 sets an initial value that takes into account environmental fluctuation factors and corresponds to a heating time to be heated to the second reference voltage V2 set lower than the control start point.
, And the timer 15 starts counting. (ST
EP 15) After the timer 15 counts up to the set value (STEP 16), the timer 15 is stopped and cleared, and then the detected voltage at that time and the second reference voltage V2 set lower are compared with the comparator 7. (STEP 17), when the detected voltage is equal to or lower than the second reference voltage V2 (S4), it is determined to be abnormal (STEP 18), and when the detected voltage is equal to or higher than the reference voltage V2 (S3), the above comparison is made. The set first reference voltage V1 is reset (STEP 19), and the hold of the control output from the comparator 7 is released to return to the normal heating operation described above (STEP 2).
0).

On the other hand, if it is determined in STEP 13 that the temperature is during the cooling process,
After performing the same operation as described above from 1 to STEP 13, the reference voltage (hereinafter, referred to as a third reference voltage V3) is set to increase in a direction exceeding the detection voltages S1, S2 based on the reference voltage generation pattern P1 (STEP 21). For example, the reference voltage in the next step may be set, or another reference voltage generation pattern Pm for error checking may be provided, and the third reference voltage V3 may be set therein. After that, the detected voltage and the relaxed third reference voltage V3 are again compared and detected by the comparator 7, and the detected voltage becomes the third reference voltage.
If the voltage is equal to or higher than V3 (S1), it is determined to be abnormal (STEP 18). If the detected voltage is equal to or lower than the third reference voltage V3 (S2), it is determined to be normal, and the process proceeds to STEP19.

Hereinafter, a similar error check operation can be performed in temperature control when shifting from the print temperature to another temperature lowering or heating temperature such as a weight temperature.

[Effects of the Invention] As described above, according to the present invention, with a simple circuit configuration, an intermediate shift step before the temperature and other physical output values output from the controlled device side are shifted to a predetermined set value. In the area, an abnormal state can be detected, thereby enabling early detection of the abnormal state.

Also, the reference voltage is relaxed in a direction approaching or exceeding the detection voltage side based on a predetermined voltage change pattern,
Since the error check is performed, it is possible to avoid the possibility of determining an abnormal state in spite of the normal state, and to detect the abnormal state with higher accuracy. And so on.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention. FIG. 2 is a block diagram showing the internal configuration of the control circuit 10. FIG. 3 is a flowchart showing the operation of this embodiment. FIG. 4 is a schematic diagram of a heat fixing device applied to the present invention. 5 and 6 are a temperature-time graph showing the temperature control state, a voltage change pattern and a graph showing its parameters. FIG. 7 shows the addresses stored in the storage means 6 or the registers 11 and 12 shown in FIG.

Claims (1)

(57) [Claims] In an abnormal state detecting method for shifting a temperature or other physical output value output from a controlled device to a predetermined set value, the physical output of the controlled device is shifted to a steady set value. When the detected voltage corresponding to the physical output value does not reach the predetermined reference voltage located in the intermediate process area, the reference voltage is set to the detected voltage based on a predetermined voltage change pattern. To determine whether there is an abnormality by comparing and determining whether the detected voltage reaches the relaxed reference voltage within a time set by a timer. If the detection voltage corresponding to the target output value has reached the predetermined reference voltage located in the intermediate process area,
The reference voltage is relaxed in a direction exceeding the detected voltage based on a predetermined voltage change pattern, and it is determined whether the detected voltage reaches the relaxed reference voltage. An abnormal state detection method characterized by detecting.