JP3283649B2 - Electronic control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device using an image fixing heater or the like used in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., and more particularly to an electronic control device for controlling the temperature by two switching elements. Related to the device.

[0002]

2. Description of the Related Art In a conventional electronic control unit for temperature control in an image forming apparatus such as a facsimile using an image fixing heater or the like, a triac is used as a switching element for turning on / off a heater, and a hot side of an AC power supply. And C
Often, two triacs are used on the old side. FIG. 8 is a block diagram of a facsimile apparatus as an example of an image forming apparatus to which the electronic control device of the present invention is applied. The facsimile apparatus includes a scanner 110 for reading a document image, a plotter 111 for writing a formed image, and an image forming apparatus. SAF 112 of information storage unit, CCU 11 of communication control unit
3. The main components are a modem 114 for connecting the apparatus to a communication line, a facsimile control unit 103a for controlling the entire system, an operation port (operation port) 115 for an operation display unit, and a DCR 116 for an image information reproduction unit. Further, the plotter 111 has a heater (not shown) for thermally fixing the formed image written by the laser, and the facsimile control unit 103a controls the heater so that the temperature to be heated by the heater becomes a constant temperature. It is controlled.

FIG. 9 is a diagram showing a conventional heater control circuit. The facsimile control unit 103a includes a heater 101.
Heater 101 by a thermistor 102a disposed near
The electronic control is performed by turning on / off the triac A 105a and the triac B 106a via the driver 104 while monitoring the temperature of the heater, so that the temperature of the object to be heated by the heater becomes constant. 10 and 11
FIG. 10 is a diagram for explaining the operation of the conventional electronic control device shown in FIG. 9; FIG. 10 shows the temperature of the heater;
FIG. 5 is a flowchart illustrating a heater temperature control procedure.
As shown in FIG. 10, the temperature to be heated by the heater 101 and the timing of turning on / off the triac A 105a and the triac B 106a at this time are set such that the temperature to be heated by the heater 101 has a certain width and the lower limit of the fixing temperature. The switching element is controlled so as to be constant between the upper limit and the upper limit.

However, the triacs used as the above two switching elements are turned on / off by the same control signal, and their lifespans are almost the same.
Although the triacs rarely fail in the on state at the same time, it is not rare that one of the triacs fails in the on state. As described above, when two triacs are turned on / off with the same signal, there is a problem that it is difficult to determine which of the switching elements has failed.

[0005]

As described above, it is not easy to determine which switching element has failed in the conventional electronic control device that performs temperature control using two switching elements, and it is difficult to replace both of them with each other. Both had to be removed and a detailed inspection had to be performed.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is to solve such a problem in the conventional heater control. That is, the present invention provides an electronic control device that facilitates determining which one of the two switching elements for performing temperature control has failed, and that is safe even if another element fails. The purpose is to:

[0007]

In order to achieve the above object, the present invention provides an electronic control device for controlling the temperature of a built-in heater by turning on / off two switching elements. A temperature detecting means for detecting a heating temperature, and a switching element control signal for controlling on / off of the two switching elements are output based on a temperature detection signal from the temperature detecting means to control the temperature of the heater. A control unit, wherein the control unit turns on / off one of the switching elements and forcibly turns off the other of the switching elements when a high temperature abnormality occurs, in accordance with the switching element control signal.
Function to control the heater to a constant temperature.
One switching element to turn on / off
Constant role with the other switching element
Swaps every time or every predetermined number of on / off
That it is characterized by being configured such that the control signal for the two switching elements are reversed activated.

[0008]

The electronic control device having the above-described structure is configured to control the switching element for turning on / off the constant temperature control via a driver from the control unit and the switching signal for forcibly turning off the switching element when the high temperature is abnormal. Since the control is turned on / off by another control signal, it is easy to determine which of the two switching elements for performing temperature control has failed, and furthermore, one of the elements has failed. Even without heating the heater without limit,
A secure electronic control device can be provided.

[0009]

Embodiments of the present invention will be described below. A facsimile apparatus as an example of an image forming apparatus to which the electronic control device of the present invention is applied has the configuration shown in FIG. That is, a scanner for reading an original image, a plotter for writing a formed image, and an SA for an image information storage unit.
F, a CCU of a communication control unit, a modem, a facsimile control unit, an operation port of an operation display unit, a DCR of an image information reproduction unit, and the like. Further, the plotter has a heater for thermally fixing the formed image written by the laser, and the facsimile control unit controls the temperature to be heated by the heater to a constant temperature. This is the same as the configuration described in the section of the related art. In this embodiment, each block code in FIG. 8 is a number in parentheses to distinguish it from the conventional facsimile.

An embodiment of the present invention applied to a facsimile having the above configuration will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of an electronic control unit according to the present invention. In Figure 1, the facsimile control section 3a, the thermistor 2a as a temperature detecting means, while monitoring the target heating temperature of the heater 1 to be heated by conduction from the AC power supply 7, the heater 1 via a driver 4
Triac A5a which is one of the switching elements 5
And a triac B6a which is the other switching element 6.
Is turned on / off to control the temperature to a constant temperature required for recording. As shown, in the present embodiment, the facsimile control unit 3a sends the driver 4
, One triac A5a and the other triac B6a are turned on / off by another control signal. FIG. 2 shows the basic operation of the electronic control device shown in the above figure.
FIG. 3 is a time chart for explaining the control procedure.
It is a flowchart shown.

In FIG. 2 and FIG. 3, for example, when the fixing temperature in the heat fixing device in the plotter 11 is made constant, first, the heater 1 is heated so that the temperature to be heated (heater temperature) becomes constant. Triac A5
a is always turned on, and the other triac B6a is turned on / off.
If either a or the triac B6a does not turn on, a failure state occurs in which the heater is not energized at all, but in this case, it is not easily known which one has failed.

However, in the case of a failure in which the triac B6a is turned on, the heater temperature exceeds the upper limit temperature. Therefore, the temperature is monitored by the thermistor 2a to detect that the temperature exceeds the upper limit.
When the triac A5a is turned off by timer means or the like (not shown), it is possible to perform an abnormal process of forcibly turning off the heater 1 when the temperature to be heated is abnormally high. is there. Also, during non-fixing, where it is not necessary to keep the fixing temperature constant,
The triac B6a is turned on. However, if the heater temperature rises, it is possible to determine that the triac A5a is on and has failed. In this case, forcibly turn off the normal triac B6a.
Just fine. FIG. 4 illustrates the operation of the electronic control device according to the present embodiment.
FIG. 5 shows the control procedure.
FIG. As shown in these figures,
The feature of the operation of the electronic control device according to the embodiment is that the function of the triac A5a and the function of the triac B6a are exchanged at regular time intervals so that the failure of the triac A5 in the ON state can be detected. . That is, in FIG. 4 and FIG. 5, in order to detect a failure in the ON state of the triac A5a, the triac A5a keeps on during fixing when the fixing temperature by the heater is fixed.
And the above-mentioned triac B6a that is turned on / off for constant temperature control is exchanged every specific period. Here, the specific period may be a fixed time during fixing, or a number of times of ON / OFF for constant temperature control. As described above, if the roles of the triacs are switched at regular time intervals or at predetermined times of on / off, as long as the triac A5a and the triac B6a do not fail simultaneously, either the triac A5a or the triac B6a is turned on. When a failure occurs in the state, it can be easily determined.

FIG. 6 is a circuit diagram showing another embodiment of the electronic control unit according to the present invention, and FIG. 7 is a time chart for explaining the operation. In this embodiment, an inverter 8 is provided between the driver 4 of FIG. 6 and the triac B6a, and as shown in FIG. 7, the control signals are Low and High.
h is activated in reverse. According to this configuration, the triac A5a and the triac B
Even if the facsimile control unit 3a other than 6a or the driver 4 or the like breaks down, or if the control signal line is disconnected, both control signals to both triacs of the driver 4 become High. The above inverter 8
, The control signal is inverted, so that both triacs are not turned on.
Is safe because it can be prevented from continuing to turn on.

[0014]

As described above, according to the present invention, the control signal of the switching element for turning on / off the constant temperature control via the driver from the control unit and the switching signal for forcibly turning off the switching element at the time of abnormal high temperature are provided. Since the control is turned on / off by another control signal, it is easy to find out which one of the two switching elements for performing temperature control has failed, and furthermore, the other elements have failed. Thus, a safe electronic control device can be provided without the heater being continuously heated.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a main part of an electronic control device according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining an operation of a main part of the electronic control device according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of a main part of the electronic control device according to the embodiment of the present invention.

FIG. 4 is a time chart for explaining an operation of a main part of the electronic control device according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of a main part of the electronic control device according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram of a configuration of a main part of an electronic control device according to another embodiment of the present invention.

FIG. 7 is a time chart for explaining an operation of a main part of an electronic control unit according to another embodiment of the present invention.

FIG. 8 is a system block diagram illustrating an example of a system to which the related art and the present invention are applied.

FIG. 9 is an explanatory diagram of a configuration of a main part of a conventional technique.

FIG. 10 is a time chart for explaining the operation of the main part of the prior art.

FIG. 11 is a flowchart illustrating the operation of the main part of the conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... heater, 2 ... temperature detection means, 2a ... thermistor, 3 ... control part, 3a ... facsimile control part, 4 ... driver, 5 ... switching element,
5a: Triac A, 6: Switching element, 6a: Triac B, 7: AC power supply, 8
... Inverter, 10 ... Scanner, 11 ... Plotter, 12 ... SAF, 13 ... CCU, 14.
..Modem, 15 ・ ・ ・ Op port, 16 ・ ・ ・ DC
R, 101: heater, 102: temperature detecting means,
102a: Thermistor, 103: Control unit, 10
3a: facsimile control unit, 104: driver, 105: switching element, 105a: triac A, 106: switching element, 106
a: Triac B, 107: AC power supply, 11
0 ... scanner, 111 ... plotter, 112 ...
・ SAF, 113 ・ ・ ・ CCU, 114 ・ ・ ・ Modem,
115 ... operation port, 116 ... DCR.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20 G03G 21/00 370-502 G03G 21/14 G05D 23/00-23/32

Claims (2)

(57) [Claims] An electronic control device for controlling the temperature of a built-in heater by turning on / off two switching elements, a temperature detecting means for detecting a temperature to be heated by the heater, and a temperature of the temperature detecting means. A control unit for outputting a switching element control signal for controlling on / off of the two switching elements based on the detection signal and controlling the temperature of the heater, wherein the control unit controls the switching element. A signal turns on / off one of the switching elements and forcibly turns off the other of the switching elements when a high temperature abnormality occurs.
Function to control the heater to a constant temperature.
One switching element to turn on / off
Constant role with the other switching element
Swaps every time or every predetermined number of on / off
An electronic control unit, characterized in that that. 2. The control for said two switching elements.
The control signal is configured to be reverse active.
The electronic control device according to claim 1.