JPH03268009A - Temperature controller - Google Patents

Abstract

PURPOSE:To execute a minute temperature control and monitoring of abnormality by a simple constitution by inputting detected temperature data obtained by an A/D converter and state data in data outputted from a latch circuit as addresses to a ROM. CONSTITUTION:The controller is constituted of a heat roll 1, a switch 2, a power source 3, a temperature sensor, an A/D converter 11, a ROM 12, and a latch circuit 13. In such a state, to the ROM 12, detected temperature data obtained by the A/D converter 11 and state data in data outputted from the latch circuit 13 are inputted as addresses. In such a way, a minute temperature control and monitoring of abnormality can be executed by a simple constitution.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention detects the temperature of an object to be heated, and controls the driving of a heating element that heats the object according to the detected salinity. The present invention relates to a temperature control device.

(Prior Art) In an electrophotographic recording device such as a laser printer, one of the fixing devices that fixes the toner transferred to the recording paper onto the recording paper.
There is a heat roll. This heat roll is a roller heated by a heater or the like that melts the toner adhering to the recording paper, and another roller that is placed opposite to the above roller and clamps the recording paper to spread the melted toner onto the recording paper. Crimp.

In such a heat roll, it is necessary to keep the temperature of the roller constant in order to obtain a stable image and ensure safety. For this reason, the temperature of the rollers is controlled, and this is usually done by thermal feedback.

FIG. 5 is a diagram showing an example of the configuration of a conventional temperature control device that controls the temperature of the heat roll as described above. In the figure,
1 is a heat roll, and a heater 1a is provided inside. The heater 1a is connected to a power source 3 via a switch 2.

On the other hand, 4a is a thermistor placed close to the heat roll 1. This thermistor 4a is connected to +
5) Connected to the power supply and grounded via resistor R2. Here, the thermistor 4a has a characteristic that its resistance changes depending on the temperature, and the voltage applied to the resistor R2 has a value corresponding to the temperature. Therefore, thermistor 4a and resistance R
By extracting the potential at the connection point A with the thermistor 4a, a voltage value corresponding to the ambient temperature of the thermistor 4a, that is, the temperature of the heat roll 1 can be obtained. In other words, the temperature sensor 4 is constituted by the thermistor 4 as resistance R1 and resistance R2.

A connection point A between the thermistor 4a and the resistor R2 is connected to the input end of the comparator 5. That is, temperature sensor 4
The output of is input to the comparator. On the other hand, the reference voltage input terminal of the comparator 5 is connected to a connection point B between resistors R3 and R4 connected in series. This resistor R3 is connected to the +5V voltage, and the resistor R4 is grounded. That is, the voltage divided by the resistors R3 and R4 is input as a reference voltage to the comparator reference voltage input terminal. Here, the resistors R3 and R4 are set so that the potential at point B is the same as the potential appearing at point A when the temperature of the heat roll 1 reaches the control target temperature.

The comparator 5 outputs +5V only when the output voltage of the temperature sensor 4 is higher than the reference voltage. The output signal of the comparator 5 is given to the switch 2 as a gate signal, and the switch 2 is turned on and off.

Thus, when the temperature of the heat roll 1 is lower than the control target temperature, the switch 2 is turned on and the heater 1a is energized and heated. Further, when the temperature of the heat roll 1 is higher than the control target temperature, the switch 2 is turned OFF and the energization heating of the heater 1a is stopped.

However, with the temperature control device configured as described above, when the temperature of the heat roll 1 is maintained at the control target temperature, there are very few fluctuations in temperature, which is good; When raising the temperature, the power supply to the heater 1a is stopped after the temperature of the heat roll 1 reaches the control target temperature, so overshoot occurs as shown in Fig. 6 due to the influence of the thermal time constant of the heat roll 1 and the heater 1a. It is undeniable that I will. If this overshoot reaches a high level, there is a risk that the life of the heat roll 1 and the heater la may be shortened.

Therefore, it has been considered to perform the following control.

That is, the energization stop temperature is set lower than the control target temperature, and when the temperature of the heat roll 1 reaches this energization stop temperature, the energization to the heater 1a is stopped. Then, the temperature is increased from the energization stop temperature to the control target temperature by an amount of overshoot due to a thermal time constant, and then, when the temperature of the heat roll 1 reaches the control target temperature, temperature control is performed using this control target temperature as a reference.

However, if it were attempted to perform the above control by improving the temperature control device shown in FIG. 5, the circuit scale would increase considerably.

Further, the above-described conventional temperature control device cannot detect abnormalities such as disconnection of the thermistor 4a, and monitoring such abnormalities requires a large increase in circuit scale.

(Problems to be Solved by the Invention) As described above, the conventional temperature control device has a problem in that the configuration becomes extremely complicated when attempting to perform detailed temperature control or abnormality monitoring.

The present invention has been made in consideration of these circumstances, and its purpose is to provide a temperature control device that has a very simple configuration and is capable of performing detailed temperature control and monitoring of abnormalities. It is about providing.

[Configuration of the Invention (Means for Solving the Problems) The present invention includes a temperature detection means for detecting the temperature of an object to be heated, and a digitalization of the detected temperature value obtained by the temperature detection means to generate detected temperature data. A/D converting means is used to store a plurality of types of n-bit data including at least driving control data and state data of the heating element, and the data stored at the address indicated by the input address data is stored in advance. storage means for outputting data in parallel; latch means for holding and outputting data output by the storage means for a predetermined period; The storage means stores the detected temperature data obtained by the A/D conversion means and the state data of the data output by the latch means. Enter it as an address.

(Function) By taking such measures, if data corresponding to the form of temperature control of the object to be heated is stored in the storage means, data corresponding to the detected temperature information and the control state at the relevant time can be stored. Control data is output from the storage means.

Therefore, it is possible to deal with various situations without adding any other mechanism.

(Embodiment) Hereinafter, a temperature control device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration in which the present temperature control device is applied to a fixing device of a laser printer. Note that the same parts as in FIG. 5 are given the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, 11 is the output voltage value (analog value) of temperature sensor 4
This is an A/D converter that converts the data into a digital value (8 bits).

The 8-bit output data of this A/D converter 11 is RO
The read addresses AO to A7 are given to M12.

Further, Q4 to Q7 of the 8-bit output of the latch circuit 13 are given to the ROM 12 as read addresses A8 to All. Based on the 12-bit address data thus applied, the ROMI 2 outputs 8-bit data 00-07 stored at the address indicated by this address data.

The 8-bit data outputted from the ROM 12 in this way is given to the latch circuit 13, and then to the A/D converter 1.
1, it is latched until data is fetched. The output of this A/D converter is given to the switch 2 as a QO low output gate signal, and the Q4 output to Q7 output are given to the ROM 12 as a read address as described above.

The latch circuit 13 is cleared when a start-up instruction is issued from the control unit of the laser printer to which the present temperature control device is applied, and the clear signal CLR input to the clear terminal becomes rLJ at the same time.

FIG. 2 is a diagram schematically showing a data table set in ROMI 2. Here, the "temperature" column corresponds to read addresses AO to A7, and is actually data of the output term of the temperature sensor corresponding to the temperature described here. Also, the "Status" column is the read address A.
8 to AIO.

FIG. 3 is a diagram showing the data format of data stored in the ROM 12. The 8-bit data stored in the ROM 12 in this way is bit ``heater control data J, bit 1 ``RDY flag J, and bit 2 ``[
Abnormal flag J, bit 3 is undefined (unused), bi
t4 to bit7 are "status data". Here, the "heater control data" is to set switch 2 to 0N10FF.
This is data for controlling the energization of the heater 1a,
If "1" is set, turn on switch 2. rRD
The "Y flag" is data for notifying the control unit of the laser printer to which this temperature control device is applied that the temperature of the heat roll 1 has reached the target temperature (control target temperature). The "abnormality flag" is data for notifying the control unit of the laser printer to which the present temperature control device is applied that an abnormality has occurred. "Status data" is data indicating the current control stage when controlling the temperature of the heat roll in stages.

Next, the operation of the temperature control device configured as above will be explained. First, when a start-up instruction is issued from the control section of the laser printer to which the present temperature control device is applied, the clear signal CLR becomes rLJ level as shown in the fourth factor, and the latch circuit 13 is cleared. Therefore, the latch circuit 13
Q7~Q4 output, i.e. state data is ro 000
It is J.

In this state, the output value of the temperature sensor (potential at point A) is digitized by the A/D converter 11, and the obtained data is given to the ROM 12 as read addresses AO to A7. Here, the temperature T indicated by the data obtained by the A/D converter 11 (hereinafter referred to as detected temperature) is the temperature T
When the temperature is below X or above TY, ROM12
As shown in FIG. Therefore, among the outputs of the latch circuit 13, only the Q2 output, which is an abnormality flag, becomes "1", indicating an abnormal state. Note that the predetermined temperatures TX and TY are below TX or TY under normal conditions.
This is a temperature that cannot exceed this temperature, and if such a temperature is detected by the temperature sensor 4, it can be determined that a failure has occurred in the temperature sensor 4, the heater 1a, or the like.

On the other hand, when the detected temperature T at startup is in the range [temperature TY<T<current discontinuation temperature TI], the ROMI 2 outputs data roooooooolJ as shown in FIG.

Therefore, the QO ratio output of the latch circuit 13, that is, the heater control signal becomes "1". As a result, the switch 2 is turned on, the heater 1a is energized, and heating of the heat roll 1 is started (point A in FIG. 4).

Then, when the temperature of the heat roll 1 rises and the detected temperature T reaches the energization stop temperature T1, ro 0 is output from the ROM 12.
Data 000000J is output. Therefore, the QO ratio output of the latch circuit 13 becomes "0", and the energization of the heater 1a is stopped (at the time point in FIG. 4). Thereafter, the temperature of the heat roll 1 increases due to the influence of the thermal time constant of the heat roll 1 and the heater 1a, and eventually reaches the control target temperature T2.

During this time, the ROM 12 continues to output data ro 0000000J.

In this state, when the detected temperature T reaches the control target temperature T2, the ROM 12 outputs rooolo as shown in FIG.
Data oloJ is output. Therefore, the Q7 to Q4 outputs of the latch circuit 13 become rooolJ, and the state data is switched.

Also, the Q1 output, that is, the RDY flag becomes "1",
You will be notified that the fixing process is ready (
Time point c in Figure 4). Here, bito is still rOJ, and the QO ratio output of the latch circuit 13 remains at "0". Therefore, the temperature of the heat roll 1 will rise slightly for a while due to the influence of the thermal time constant.

When the temperature rise due to the thermal time constant stops, the temperature of the heat roll 1 starts to fall. Then, when the detected temperature T becomes lower than the control target temperature T2, the detected temperature T becomes [T1
≦T<T2].

However, the Q7 to Q4 outputs of the latch circuit 13, that is, R
Read addresses All to A8 of OMI 2 are roool
J, the output data of ROM12 is r00.
0]0011J. Therefore, the QO of the latch circuit 13
The specific output, that is, the heater control signal becomes "1". As a result, the switch 2 is turned on and the energization of the heater 1a is resumed (point 2 in FIG. 4). At this time, the latch circuit 13
The Q1 output of continues to be "1" and remains in the RDY state.

Then, when the detected temperature T exceeds the control target temperature T2 again,
The data rooolooloJ is output from the ROM 12, and the energization of the heater 1a is stopped (time E in FIG. 4).

Thus, when the state data is rooolJ,
When the detected temperature T is higher than the control target temperature T2, ROM1
2 outputs data that bftO is rOJ, and when the detected temperature T is lower than the control target temperature T2, the ROM
12 outputs data whose bltO is "1".

Therefore, the temperature of the heat roll 1 is maintained at the control target temperature T2.

Note that even in a state where the status data is rooolJ, if the detected temperature T is below the temperature TX or above the temperature TY, the ROMI 2 outputs the data rooololooJ with bit 2, which is the abnormality flag, set to "1". . In addition, in a state where the state data is rooolJ, the detected temperature T is [temperature TY<T<current discontinuation temperature Tl
If the temperature is within the range of l, it is possible that the temperature of the heat roll 1 will not rise due to a failure of the heater 1a, etc.
The ROM 12 outputs data rooololoooJ with bit 2, which is an abnormality flag, set to "1".

As described above, according to this embodiment, the data obtained by digitizing the temperature information (potential) obtained by the temperature sensor 4 and the R
Since the 4 bits of the previous output data of the OM 12 are used as the read address of the ROM 12, the A/D converter 11. R
OMI 2. Two-step temperature control can be performed with a very simple configuration of the latch circuit 13. In addition, the data stored in the ROM 12 includes an RDY flag and an abnormality flag, and these are output according to the detected temperature, so abnormality monitoring and other functions can be performed without adding any special mechanism. It is possible to perform additional processing.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, temperature control is performed in two stages, and the state data is set to two, ro O00J and rooolJ, but it is also possible to perform more detailed temperature control in multiple stages. In this case, the configuration of the above embodiment takes 4 bits of state data and can represent up to 16 states, so data corresponding to each can be added and stored in the ROM 12 without changing the configuration until 16 levels of temperature control are achieved. It can be achieved just by doing. In addition, the lever that controls more than 17 levels, R
The number of bits of state data may be increased by increasing the number of bits of data stored in OMI 2, for example.

Further, the data stored in the ROMI 2 and its format are not limited to those mentioned in the above embodiments, and may be any data and data format as required. Furthermore, in the above embodiment, a ROM is used as a storage means.
However, for example, a RAM may be used and the data may be rewritten as necessary.

Further, in the above embodiment, the temperature control device according to the present invention is applied to a temperature control device of a laser printer, but the temperature control device of the present invention can be applied to any heat generating device that needs to control the heat generation temperature to a constant temperature. Applicable, therefore, the heating element and the heated object are not limited to the heater and the heat roll. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, there are provided a temperature detection means for detecting the temperature of an object to be heated, and an A/D conversion means for digitizing the detected temperature value obtained by the temperature detection means to obtain detected temperature data. and a storage means in which a plurality of types of n-bit data including at least drive control data and status data of the heating element are stored in advance, and the data stored in the address indicated by the input address data is output in parallel. , a latch means for holding and outputting data output by the storage means for a predetermined period of time, and a heat generating drive means for driving the heat generating element based on the drive control data of the n-bit data output from the latch means. Further, the storage means inputs the detected temperature data obtained by the A/D conversion means and the state data of the data outputted by the latch means as an address, The present invention provides a temperature control device that can perform detailed temperature control and monitor abnormalities while having a simple configuration.

[Brief explanation of drawings]

1 to 4 are diagrams explaining a temperature control device according to an embodiment of the present invention, and FIG. 1 is a diagram showing a configuration when the temperature control device is applied to a fixing device of a laser printer. , FIG. 2 is a diagram schematically showing a data table stored in ROM 12 in FIG. 1, and FIG. 3 is a diagram schematically showing a data table stored in ROM 12 in FIG.
A diagram showing the data format of data stored in 2.
FIG. 4 is a time chart showing operation timing, and FIGS. 5 and 6 are diagrams each explaining the prior art. 1... Heat roll, 1 a'' heater, 2...
Switch, 3...Power supply, 4...Temperature sensor, 4a.
...Thermistor, 11...A/D converter, 12...
ROM, 13...Latch circuit.

Claims (1)

[Scope of Claims] A temperature control device for controlling the temperature of a heated object heated by a heating element to a predetermined temperature, comprising: temperature detection means for detecting the temperature of the heated object; and a temperature detection means for detecting the temperature of the heated object; A/D conversion means for digitizing the value of the detected temperature as detected temperature data; and an address to which a plurality of types of n-bit data including at least drive control data and status data of the heating element are stored in advance; A storage means for outputting data stored in an address indicated by the data in parallel; a latch means for holding and outputting the data outputted by the storage means for a predetermined period; a heat generating drive means for driving the heat generating element based on the drive control data;
A temperature control device characterized in that the detected temperature data obtained by the D conversion means and the state data among the data output by the latch means are input as addresses.