JPH08314335A - Power source device - Google Patents

Abstract

PURPOSE: To provide a power source device capable of shortening the warm-up time of a copying machine without allowing the electric power to be consumed by a heater to exceed a regulated value. CONSTITUTION: The signal corresponding to the voltage of AC input 1 is outputted to a CPU 7 from the one side waveform peak at a point (A) by an input voltage detecting means 12. At what V is the present AC input voltage is recognized in the CPU 7. Wait time Δt is subjected to table reference from the AC input voltage and further, ΔT which is the quantity of the deviation between the true zero cross of the AC input voltage and the detection signal edge falling to 'L' from 'H' to the in port of an AC monitor, from the AC input voltage and the rise and fall of the AC input voltage. The zero cross detection signal outputted from a transistor 102 is taken into the CPU 7 and thereafter, the signal is waited by ΔT time, and further Δt time and a start pulse is outputted from the heater control port of the CPU 7 to a triac 5 to energize a heater 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device suitable for being incorporated in a copying machine, a printer or the like.

[0002]

2. Description of the Related Art In general, electrical appliances, office automation equipment, etc., must clearly indicate and comply with the maximum current consumption from an outlet in terms of product specifications and safety standards. For example, in a copying machine of 100V15A, if 11A is consumed by the fixing unit heater unit and 4A is consumed by the other units, it falls within the standard.

An example of a power supply device used in such a copying machine is shown below.

FIG. 1 is a circuit configuration diagram of a conventional power supply device (the circuit of the power supply device of the embodiment is the same as the wiring itself), FIG. 5 is a waveform diagram of each part in the conventional example, and FIG.
It is an AC input voltage characteristic view of wait time Δt.

In the circuit shown in FIG. 1, 1 is an AC input, 2 is a diode bridge, 3 is a transformer, 4 is a heater of a fixing unit incorporated in a copying machine, 5 is a triac,
Reference numeral 6 is a phototriac, 7 is a power supply control CPU, 8 is a primary / secondary insulating element, 10 is a three-terminal regulator, 11 is a thermistor for detecting the temperature of the heater 4, and 12 is an AC input voltage detecting means.

Next, the operation of each section will be described.

The voltage waveform shown in FIG. 5A is input to the AC input 1, the diode bridge 2 and the capacitor 20.
It is supplied to the primary side of the transformer 3 via 1. here,
The transistor 101 is turned on / off by a control signal from the CPU 7 via the insulating element 8, and
LC with the inductance of the next coil and the capacitor 202
Resonance is generated to generate an AC waveform on the secondary side of the transformer 3, and this AC waveform is converted into a DC current by the diode 301 and the capacitor 203.

This DC-converted voltage is applied to the CPU 7 by +24.
The + 24V control port of the CPU 7 outputs a signal for controlling the ON width or OFF width of the control signal supplied to the transistor 101 so that the voltage is taken into the V monitor port and becomes 24V. This 24V signal is supplied to each unit in the copying machine.

A signal output from the AC input 1 to the secondary side of the AC input 1 via the transformer 9 is supplied to the AC input voltage detecting means 1.
2 and input the detection signal corresponding to the AC input voltage to the CPU
It is taken into the AC monitor in port of 7.

Further, the signal output from the transformer 9 is input to the base of the transistor 102, and the AC input 1 becomes 0.
A 0-cross signal that rises or falls at the timing of crossing the points is fetched into the 0-cross in port of the CPU 7.

Further, the signal output from the transformer 9 is converted into a direct current by the diode 302 and the capacitor 204 to output a voltage of + 5V via the three-terminal regulator 10, which is operated by a + 5V power source such as the CPU 7. Supply to the unit.

An ON / OFF signal is supplied to the phototriac 6 from the heater control port of the CPU 7, and an AC input voltage 1 is applied to the heater 4 under the control of the triac 5. The thermistor 11 is the heater 4
The detection signal corresponding to the temperature is supplied to the temperature detection port of the CPU 7.

Next, the operation of the entire circuit will be described with reference to the waveform chart of FIG.

First, the AC input voltage detecting means 12 detects what voltage the current AC input voltage (a) is, and outputs it to the AC monitor in port of the CPU 7.

Then, the wait time Δt at which desired power is supplied to the heater 4 by the control of the triac 5 by this AC input voltage is calculated or calculated in advance in the CPU 7 according to the characteristic diagram of FIG. Determined by looking up the table. (This characteristic diagram is
Heater power: 1100 W, resistance value: 7.6 Ω, AC input voltage frequency: 50 Hz.) After that, the wait time Δt calculated above is added to the timing (b) input to the 0 cross in port. At the timing (c), the heater control port of the CPU 7 outputs a pulse for a desired ON holding time of the triac 5 or more, and a voltage is applied to the heater 4 (d). By repeating this operation, almost constant power is applied to the heater 4 irrespective of the voltage of the AC input 1 to obtain a desired temperature rise. After the heater 4 reaches the target temperature, the thermistor 11 detects the temperature of the heater 4, and feedback control is performed to finely adjust the wait time Δt so as to match the set temperature.

[0016]

However, in the above-mentioned conventional example, when a load of +5 V is pulled, the + side of the voltage waveform is scraped by the output impedance of the transformer 9 as shown in FIG. In addition, due to the primary and secondary transfer characteristics (frequency dependence) of the transformer, the phase difference between the 0 cross point of the voltage waveform of the AC input 1 and the signal supplied to the 0 cross in port of the CPU 7 is the AC input voltage, It varies depending on the frequency and the rise and fall of the AC input voltage waveform.

Therefore, the timing at which the heater 4 is energized is also deviated by the AC input voltage, the frequency, and the rise and fall of the AC input voltage waveform, so that the fuser heater unit may consume a current of 11 A or more. (Since the AC voltage detecting means 12 detects the − side peak of the waveform of (A), no problem occurs.)

Further, the electric power supplied to the heater 4 also varies at that time, and thermal overshoot occurs when the temperature of the heater is raised, and the fuser heater unit is overheated and protected. The operation may be activated or the heater may be destroyed.

Therefore, in the above conventional example, the wait time Δ
Considering a large value of t in advance, a margin is provided so that the maximum current consumption of the fixing unit heater unit does not exceed 11 A. As a result, it takes a long time for the fixing unit heater unit to converge to the set temperature. Therefore, there is a drawback that the warm-up time of the copying machine increases.

The present invention has been made in order to eliminate the drawbacks of the conventional example, and the phase difference between the 0 cross signal and the AC input voltage generated by pulling the load can be calculated as the AC input voltage and frequency, and By correcting the rise and fall of the AC input voltage waveform, the power consumed by the heater will not exceed the specified value,
Moreover, it is an object of the present invention to provide a power supply device that can shorten the warm-up time of a copying machine or the like because it is not necessary to set the time for energizing the heater to be short.

[0021]

The power supply device of the present invention is constructed as follows.

(1) A transformer connected to the AC input,
Voltage detecting means for detecting the voltage on the secondary winding side of the transformer, zero cross detecting means for detecting the timing of zero cross of the signal on the secondary winding side of the transformer, and a load,
The switch means is provided with a switch means for controlling the power applied to the load, and a control means for controlling the timing of the switch control of the switch means based on the outputs of the voltage detecting means and the zero-cross detecting means. It corrects the switch control timing according to the voltage detected by the detection means and the falling and rising edges of the voltage.

(2) A transformer connected to the AC input,
Voltage detection means for detecting the voltage and frequency on the secondary winding side of the transformer, zero cross detection means for detecting the zero-cross timing of the signal on the secondary winding side of the transformer, load, and power applied to the load. Switch means for controlling the switch, and control means for controlling the timing of the switch control of the switch means based on the outputs of the voltage detecting means and the zero-cross detecting means, the control means being detected by the voltage detecting means. Corrects the switch control timing according to the voltage and frequency, and the fall and rise of that voltage.

Here, in the power supply device of the above (1) and (2), the control means corrects the deviation between the true zero-cross timing of the AC input and the zero-cross timing detected by the detection means by the zero-cross detection means. Correct the switch control timing.

Further, the control means includes a correction table,
The timing of switch control can be controlled by referring to this correction table.

[0026]

Since the power supply device of the present invention is configured as described above, it is possible to prevent the transformer from changing due to variations in the magnitude of the AC input voltage, rising and falling, and (in the above (2), further frequency). Even if the zero-cross detection timing detected by the zero-cross detection means changes due to the load on the secondary winding side, the control means performs the control in which the phase control timing is corrected, so that the power applied to the load is set to a desired value. It can be controlled correctly.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In this embodiment, the wiring of the circuit of the power supply device is the same as that described in the conventional example (FIG. 1), and therefore the same symbols as those described in the conventional example are used for the description. Omit it. That is, the difference between this example and the conventional example is
It is in the control operation of the voltage.

FIG. 2 is a waveform diagram of each part in this embodiment,
FIG. 3 is a diagram showing ΔT correction data provided in the CPU 7 in the present embodiment. Further, the AC input characteristic diagram of the wait time Δt of FIG. 6 similar to the conventional example is also used.

The operation of this embodiment will be described below with reference to FIGS. 1, 2, 3, and 6.

First, in the AC input voltage detecting means 12, from the peak of the − side waveform (FIG. 2A) at point (A) in FIG.
A signal corresponding to the voltage of C input 1 (Fig. 2 (a)) is sent to the CPU.
By outputting to the CPU 7, the CPU 7 recognizes what V the current AC input voltage is.

Next, from the AC input voltage recognized by the AC input detecting means 12 described above, Δt in FIG. 6 is further calculated, and from the AC input voltage and the rise and fall of the AC input voltage, the true AC input voltage of FIG. Reference is made to the table for ΔT, which is the time for correcting the zero-crossing and the detection signal edge shift from “H” to “L” (or “L” to “H”) to the AC monitor in port.

After the 0 cross detection signal (FIG. 2B) output from the transistor 102 is fetched by the CPU 7,
Wait for the time of ΔT (ΔT may have both “+” and “−” signs), wait for the time of Δt, and start from the heater control port of the CPU 7 to the triac 5 via the phototriac 6. A pulse (Fig. 2 (c)) is output to energize the heater 4 (Fig. 2).
(D)).

When referring to Δt and ΔT in a table, Δt is previously set to Δt in order to reduce the number of reference tables.
A method of preparing a table of ΔS to which T is added, capturing the 0-cross detection signal by the CPU 7, outputting a start pulse to the triac 5 by waiting for the time of ΔS, and starting energization of the heater 4 is also the same. It goes without saying that it can be carried out.

In this way, even if the 0 cross detection timing fluctuates due to the magnitude of the voltage of the AC input 1 and the rising and falling of the AC input voltage waveform due to the + 5V system load being applied, the correction is made with ΔT. By doing so, the consumption current and the applied power of the heater 4 can be correctly controlled to desired values.

When the wait time Δt is referred to in the table, the effective voltage applied to the heater: V (determined from the heater resistance value and the power) AC input voltage effective value: E AC input half cycle time: T Heater power: P heater resistance value: R, P = E2 / R [1- [Delta] t / T + {sin ( ² [pi] [Delta] t /
T)} / 2π], V ² / E ² = 1−Δt / T + {sin (2πΔt /
T)} / 2π, and Δt / T is looked up from the ratio of the effective value of the AC input voltage to the voltage applied to the heater.
It can also be implemented by obtaining t.

(Embodiment 2) FIG. 4 shows the CPU 7 in this embodiment.
It is a figure which shows the correction data of (DELTA) T with which it is equipped. Here, (A) is (B) when the frequency of the AC input is 50 Hz.
Is for 60 Hz. In the present embodiment, since the transfer characteristic of the transformer 9 changes depending on the frequency of the AC input 1, the correction data of ΔT includes the voltage and frequency of the AC input 1, and the rising and falling edges of the AC input voltage waveform. The feature is that it is corrected by.

The power supply device of this embodiment is also connected in the same manner as in the first embodiment.
Alternatively, it is the same as that used in the conventional example (FIG. 1). Further, the AC input characteristic diagram of the wait time Δt of FIG. 6 similar to the conventional example is also used.

The operation of this embodiment will be described below with reference to FIGS. 1, 4, and 6.

First, the AC input voltage detecting means 12 outputs a signal corresponding to the voltage and frequency of the AC input 1 to the CPU 7 from the − side waveform peak of point (A) of FIG. Recognize what the AC input voltage is and what the frequency is at Hz.

Next, from the AC input voltage recognized by the AC input detecting means 12 described above, Δt in FIG. 6 is further calculated, and from the AC input voltage and frequency and the rise and fall of the AC input voltage, the AC input voltage in FIG. The table is referred to ΔT, which is the time for correcting the true zero crossing and the detection signal edge shift from “H” to “L” (or “L” to “H”) to the AC monitor in-port.

After the 0 cross detection signal output from the transistor 102 is taken in by the CPU 7, it is waited for the above ΔT time (ΔT may have both “+” and “−” signs), and further for the above Δt time. Wait, CPU
Output a start pulse from the heater control port of 7 to the triac 5 via the photo triac 6,
Energize the heater 4.

In this way, even if the 0-cross detection timing fluctuates due to the magnitude and frequency of the voltage of the AC input 1 and the rise and fall of the AC input voltage waveform due to the + 5V system load being drawn, ΔT By correcting the current consumption, the current consumption and the applied power of the heater 4 can be properly controlled to desired values.

[0044]

As described above, when the power supply device of the present invention is used in, for example, a copying machine, the power consumed by the heater does not exceed the specified value, and the warm-up is performed. The time can be shortened.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a power supply device to which the present invention is applied.

FIG. 2 is a waveform chart of each part of the first embodiment.

FIG. 3 is a diagram showing ΔT correction data according to the first embodiment.

FIG. 4 is a diagram showing ΔT correction data according to the second embodiment.

FIG. 5 is a waveform chart of each part of a conventional example

FIG. 6 AC input voltage characteristic diagram of Δt

[Explanation of symbols]

 1 AC Input 4 Heater 5 Triac 6 Phototriac 7 Power Control CPU 9 Transformer 12 AC Input Voltage Detection Means 102 Transistor

Claims (4)

[Claims] 1. A transformer connected to an AC input, voltage detection means for detecting a voltage on the secondary winding side of the transformer, and zero cross for detecting a zero cross timing of a signal on the secondary winding side of the transformer. A detection means, a load, a switch means for switch controlling the power applied to the load, and a control means for controlling the switch control timing of the switch means based on the outputs of the voltage detection means and the zero-cross detection means, The control means corrects the switch control timing according to the voltage detected by the voltage detection means and the fall and rise of the voltage. 2. A transformer connected to an AC input, a voltage detecting means for detecting a voltage and a frequency on the secondary winding side of the transformer, and a zero cross timing of a signal on the secondary winding side of the transformer. Zero cross detection means
A load, a switch means for controlling the power applied to the load, and a control means for controlling the timing of the switch control of the switch means based on the outputs of the voltage detection means and the zero-cross detection means. A power supply device for correcting the timing of switch control according to the voltage and frequency detected by the voltage detecting means and the falling and rising of the voltage. 3. The control means corrects the switch control timing so as to correct the deviation between the true zero-cross timing of the AC input and the zero-cross timing detected by the detection means by the zero-cross detection means. 1
Alternatively, the power supply device according to item 2. 4. The power supply device according to claim 1, wherein the control unit includes a correction table, and controls the switch control timing by referring to the correction table.