JP2002123122A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device constituted so that long warm-up time is not required until shifting to an operation mode when power is wastefully consumed at standby time and standby is released and further capable of always supplying nearly constant power to a fixing heater even when the voltage of a power source is fluctuated. SOLUTION: This image forming device equipped with a fixing means having a fixing heater to which the voltage is applied from the power source through a control circuit is provided with a temperature detection means for detecting the temperature of the fixing heater and a current detection means for detecting the current consumption of the fixing heater. It is equipped with the control circuit energizing the fixing heater so that the detected current consumption may be previously set current consumption value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a fixing means having a fixing heater to which a voltage is applied from a power supply via a control circuit.

[0002]

2. Description of the Related Art Conventionally, this type of image forming apparatus has a problem that wasteful power is consumed during standby, and a long warm-up time is required to shift to an operation mode when standby is released. . Then, in order to solve such a problem, the one disclosed in Japanese Patent Application Laid-Open No. 9-230741 has been proposed.

In order to solve the above-mentioned problems, such an already proposed image forming apparatus has a power consumption measuring means for the fixing heater and a control means to which the measured power consumption value is inputted. The control means is configured to supply power to the fixing heater by phase control so that the measured power consumption value becomes a preset power consumption measurement value during standby of the fixing operation.

[0004]

However, such an image forming apparatus operates only in a limited standby state, and what operation is performed when the operation state is switched to the standby state. There is a problem that no consideration is given as to whether or not to cope with this, and a means for detecting power consumption is lacking, so that it cannot be an effective means for solving the above-mentioned problem.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the proposed image forming apparatus, to consume wasteful power during standby and to shift to an operation mode when standby is released. Another object of the present invention is to provide an image forming apparatus which can supply a substantially constant power to the fixing heater even when the voltage of the power supply fluctuates, in addition to the fact that a long warm-up time is not required.

[0006]

According to the present invention, there is provided an image forming apparatus including a fixing unit having a fixing heater to which a voltage is applied from a power supply via a control circuit in order to achieve the above object. According to a first aspect of the present invention, there is provided a temperature detecting means for detecting a temperature of the fixing heater, and a current detecting means for detecting a current consumption of the fixing heater, wherein the detected current consumption is a preset current consumption value. And a control circuit for energizing the fixing heater.

According to a second aspect of the present invention, there is provided a current detecting means for detecting current consumption of the fixing heater, and a calculating means for calculating power consumption from the detected current consumption. A control circuit for energizing the fixing heater so that the power consumption value is set in advance is provided.

According to a third aspect of the present invention, there is provided a current detecting means for detecting a current consumption of the fixing heater, and when the fixing heater enters a standby state, a power consumption is calculated from the detected current consumption. When the fixing heater enters a standby state, the temperature detecting means detects this, and the fixing heater is controlled so that the power consumption value in the standby state becomes a power consumption value in a preset standby mode. It is characterized by comprising a control circuit for energizing.

The invention according to claim 4 is characterized in that the detected and calculated current consumption and power consumption values are average values over a certain period of time.

The invention according to claim 5 is characterized in that the preset current consumption and power consumption values are of two types, ie, during operation and during standby.

According to a sixth aspect of the present invention, the means for detecting the current consumption of the fixing heater comprises a current transformer between the AC power supply and the fixing heater.

According to a seventh aspect of the present invention, when it is not necessary to detect the current consumption and power consumption of the fixing heater, the detection is not performed by providing a switching means in the control means. It is assumed that.

[0013]

FIG. 1 shows a first embodiment of the present invention, wherein 1 is a commercial power supply, 2 is a fixing heater, 3 is a relay, 4 is a triac, 5 is a thermistor, and 6 is a control. A circuit, 7 is a current consumption detection circuit, and 8 is a CPU. When the power is not turned on, the relay 3 and the triac 4 are set to the initial state of off.

Here, the thermistor 5 has a temperature detector for converting the temperature of the fixing heater 2 into a voltage by a built-in resistor, and the control circuit 6 has a first comparator 11 therein. It has a function of comparing the sent temperature information with a target temperature preset in the first comparator 11. Further, it has a function of turning on / off the relay 3 and the triac 4 in response to a control signal from the CPU 8.

The current consumption detection circuit 7 has a function of detecting the current consumption flowing from the commercial power supply 1 to this circuit as needed.
The detected consumption current is sent to the control circuit 6. The control circuit 6 internally has a second comparator different from the first comparator 11.
The second comparator 12 has a function of comparing a current consumption value sent from the current consumption detection circuit 7 with a target current consumption value preset in the second comparator 12. Here, the control circuit 6 has a function of calculating and comparing an average value for a certain period of time, instead of comparing the transmitted current consumption values as they are.
Here, the target temperature and current consumption values are
8 to the first and second comparators 11 and 12.

In such an apparatus, when the power is turned on, the CPU 8 executes an initial setting process. As one of the initial setting processes, the CPU 8 executes a control circuit to heat the fixing heater 2 to a predetermined temperature. The control signal is output to 6. Then, the control circuit 6 receives this control signal, outputs a gate signal, and turns on the relay 3 and the triac 4 in this order.

In this state, the fixing heater 2 is heated and the temperature gradually rises. However, when the control circuit 6 recognizes that the target temperature has been exceeded, the consumed current detected by the consumed current detection circuit from this state is detected. The control circuit 6 recognizes the value. Then, the control circuit 6 calculates the consumption current value
An average value over a certain period of time is calculated and compared with a target current consumption value as needed. In this case, the certain period of time is defined as a period from the end of one print operation during the operation.
One cycle is defined as the time when the next printing operation is completed, and one cycle or several cycles.

Here, when the image forming apparatus is ready for printing and the paper feeding is started, the fixing heater 2
When the paper to be printed loses heat and the paper is continuously passed, the temperature of the fixing heater 2 is repeatedly increased and decreased by the temperature control function of the fixing heater circuit. Is common.

In such an operation state, the control circuit 6 frequently turns on / off the triac 4 to control the energization of the fixing heater 2, but as a result, the current consumption value fluctuates drastically. Become. The current consumption value fluctuating at this time is constantly detected by the current consumption detection circuit 7, and the detected value is sent to the control circuit 6. The control circuit 6 calculates the average value of the current consumption and the target current consumption during operation. Performs a value comparison.

If the detected current consumption value is equal to or less than the target, the control circuit 6 does not perform any control, and if the current consumption value exceeds the target due to fluctuations in the commercial power supply voltage or the like, the control circuit 6 Is controlled such that the paper passing interval is increased so that the value becomes a numerical value equal to or smaller than the target. Under the control of the control circuit 6, the current consumption during the operation of the fixing heater 2 can be kept substantially constant.

Next, the second embodiment shown in FIG. 2 differs from the first embodiment in that a current consumption / voltage circuit 9 is provided in place of the current consumption detection circuit 7 and a power consumption calculation circuit 10 is further provided. Others are the same.

In this embodiment, the current consumption / voltage circuit 9 has a function of detecting the current consumption and the voltage flowing from the commercial power supply 1 to the circuit at any time. The power consumption is calculated by multiplying the current value and the voltage value, and the calculated power consumption value is transmitted to the control circuit 6.

The control circuit 6 has a function of comparing the transmitted power consumption value with a target power consumption value preset in the built-in comparator 12. Here, similarly to the current consumption value in the first embodiment, the control circuit 6 has a function of calculating the transmitted current consumption value as an average value for a certain period of time and comparing the average value with a target.

In this embodiment, when the fixing heater 2 is in the operating state, a current consumption value and a voltage value are detected, the power consumption calculation circuit 10 calculates the power consumption from the detected values, and the control circuit 6 sets a target power consumption. A comparison with the power value is made. If the calculated power consumption value exceeds the target, the power consumption is controlled to be equal to or smaller than the target, as in the first embodiment. With such a control method, the power consumption of the fixing heater 2 can be kept substantially constant. Further, compared to the first embodiment, the control is performed by detecting the power consumption value, so that the accuracy is further improved.

Next, a description will be given of the control of power consumption and the like when the fixing heater 2 of this embodiment is in a standby state.
When the CPU 8 detects that the image forming apparatus has shifted from the operation state to the standby state, the power consumption value in the standby mode is set to the second comparator 12 in the control circuit 6 this time.
In the same manner as in the second embodiment, the comparison between the average value and the set value of the standby power consumption data transmitted from the current consumption / voltage circuit 9 to the control circuit 6 via the power consumption calculation circuit 10 is performed. Do.

If the detected power consumption data exceeds the set value due to the deterioration of the power supply or the like, control such as further extending the power supply to the fixing heater 2 is performed. So that In this case, it is sufficient that the average value of the power consumption is an average value after entering the standby mode or an average value for a predetermined time (about 3 minutes) before comparison.

Next, a third embodiment will be described with reference to FIG. In this embodiment, as shown in FIG. 3, a current transformer (hereinafter referred to as CT) 17 and a conversion circuit 19 from AC to DC are used as current / voltage detection means.
And to use. After the AC current flowing from the commercial power supply 1 is converted into a DC current by the conversion circuit 19, the primary current flowing in the primary winding is Ic, and the secondary current flowing in the secondary winding is Ic.
s If the number of primary / secondary turns is N1 / N2, the following equation holds. Is = (N1 / N2) · Ic

Thus, the secondary current Is can be detected. Further, a resistor Rsc is connected to detect a voltage applied to the secondary current. At this time, Vrs = Is · Rsc = (N1 / N2) · Ic · Rsc at both ends of Rsc, and a voltage Vrs proportional to Ic can be detected. Thus, according to the N1 / N2 turns ratio of CT,
There is a correlation between Ic and Is, Vrs.

Between Ic and commercial power supply voltage Vin, Ic
Since there is a correlation of large c → large Vin, small Ic → minimum Vin, a correlation is also established between Vin and Vrs. When configuring this embodiment, the actual current value of Ic and the commercial power supply voltage Vin at that time are measured, and Ic
By setting the correlation data of -Is, Vin-Vrs in the storage means in the control circuit, the control circuit can always detect the current value Ic applied to the fixing heater and the voltage value Vin. Control other than the above is based on the first embodiment. By using the CT in this way, it is possible to accurately detect the current consumption / voltage.

Next, a fourth embodiment will be described with reference to FIG. In an image forming apparatus such as the present invention,
It is conceivable that control by power consumption is not necessarily required, such as when the possibility that the power supply situation deteriorates is low. In such a case, a switching means is provided so as to be able to cope with only the conventional control method based on temperature control, and the power consumption control method is selected. This embodiment belongs to such a concept, and includes a switch 13 which forms on / off means.
Is provided in the connection line between the commercial power supply 1 and the fixing heater 2, and when the switch 13 is selected to the position A by the control circuit 6, the conventional control system is used. The operation is performed in accordance with the above-described embodiments.

As another example, when switching means is provided inside the control circuit 6 and the conventional control method is selected, even if power consumption is detected by the power consumption detection circuit at the time of energization,
The control circuit 6 may not detect this. As described above, by providing the switching means for controlling the current consumption and power consumption of the fixing heater and the conventional control method, it is possible to perform a usage method corresponding to a situation by selecting the method.

[0032]

The present invention is as described above, and in the image forming apparatus, the invention according to the first aspect is a temperature detecting means for detecting the temperature of the fixing heater, and a current detecting means for detecting a current consumption of the fixing heater. And a control circuit for energizing the fixing heater so that the detected current consumption becomes a preset current consumption value. There is an effect that almost constant power can always be supplied.

According to a second aspect of the present invention, there is provided a current detecting means for detecting current consumption of the fixing heater, and a calculating means for calculating power consumption from the detected current consumption. Since a control circuit for energizing the fixing heater is provided so as to attain a preset power consumption value, it is possible to supply a fixed power to the fixing heater with higher accuracy than the first aspect of the present invention. effective.

According to a third aspect of the present invention, there is provided a current detecting means for detecting a current consumption of the fixing heater, and when the fixing heater enters a standby state, a power consumption is calculated from the detected current consumption. When the fixing heater enters a standby state, the temperature detecting means detects this, and the fixing heater is controlled so that the power consumption value in the standby state becomes a power consumption value in a preset standby mode. Since the power supply control circuit is provided, even when the fixing heater shifts from the operating state to the standby state, it is possible to suppress the power consumption to less than the power consumption in the standby mode.

According to a fourth aspect of the present invention, the detected and calculated current consumption and power consumption values comprise an average value for a certain period of time, and by comparing this average value with a target, efficient energy saving is achieved. There is an effect that can be realized.

According to the fifth aspect of the present invention, since the preset current consumption and power consumption values are of two types, that is, during operation and during standby, the same effects as those of the first, second, and third aspects are obtained. There is.

According to a sixth aspect of the present invention, the means for detecting the current consumption of the fixing heater comprises a device using a current transformer between the AC power supply and the fixing heater. Can be detected with high accuracy, and the effects of the inventions according to the first, second, and third aspects can be improved.

According to the seventh aspect of the present invention, when it is not necessary to detect the current consumption and power consumption of the fixing heater, the control unit is provided with a switching unit so that the detection is not performed. There is an effect that it can be used according to the circumstances.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a main part of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional front view of a main part according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional front view of a main part of a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional front view of a main part of a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Fixing heater 3 Relay 4 Triac 5 Thermistor 6 Control circuit 7 Current consumption detection circuit 8 CPU 9 Current consumption / voltage circuit 10 Power consumption operation circuit 11 First comparator 12 Second comparator 13 Switch

Claims (7)

[Claims] 1. An image forming apparatus comprising: a fixing heater to which a voltage is applied from a power supply via a control circuit; and a temperature detecting means for detecting a temperature of the fixing heater. An image forming apparatus, comprising: a detecting unit; and a control circuit that energizes the fixing heater so that the detected current consumption becomes a preset current consumption value. 2. An image forming apparatus comprising: a fixing heater to which a voltage is applied from a power supply via a control circuit; and a temperature detecting means for detecting a temperature of the fixing heater. A control circuit for energizing the fixing heater so as to have a detection unit and a calculation unit for calculating power consumption from the detected current consumption, so that the calculated power consumption value becomes a preset power consumption value; An image forming apparatus. 3. An image forming apparatus comprising: a fixing heater to which a voltage is applied from a power supply via a control circuit; and a temperature detecting means for detecting a temperature of the fixing heater. Calculating means for calculating power consumption from the detected current consumption when the fixing heater enters a standby state; and An image forming apparatus, comprising: a control circuit that detects this, and energizes a fixing heater so that a power consumption value during standby becomes a power consumption value in a standby mode set in advance. 4. The image forming apparatus according to claim 1, wherein the detected and calculated current consumption and power consumption values are average values over a certain period of time. 5. The preset current consumption and power consumption values are:
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus comprises two types: an operation time and a standby time. 6. The image according to claim 1, wherein the detecting means for detecting the power consumption of the fixing heater includes a current transformer between the AC power supply and the fixing heater. Forming equipment. 7. When the detection of the current consumption and power consumption of the fixing heater is not required, a switching device is provided in the control circuit so that the detection is not performed. The image forming apparatus according to any one of the above.