JPS6039668A - Lamp controller - Google Patents

Abstract

PURPOSE:To start converging a phase control angle at a proper value to a turn- on voltage desired value speedily by storing the phase control angle in the ending of each scanning exposure operation in a microcomputer when plural sheets are copied, and using it as the starting phase control angle of scanning on the next original. CONSTITUTION:The controller for a halogen lamp 2 consists of a power source 1, gate control rectifying circuit 5 for a triac 3, trigger element 6, zero-cross circuit A, detecting circuit B for the lighting operation and effective value of the lamp 2, microcomputer 27, etc. The turn-on voltage of the lamp 2 is controlled by the microcomputer 27. At this time, the phase control angle in the ending of every exposure scanning in the copying of pulural sheets is stored in the microcomputer 27. The phase control angle stored in the microcomputer 27 is used as the starting phase control angle of scanning on the next original to turn on the lamp 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lamp control device that controls the power of a lamp.

A copying apparatus will be explained below as an example.

Conventionally, the power of a halogen lamp used in a document exposure lamp of a copying machine has been controlled by phase control using a lamp regulator (CVR). The CVR has a complicated circuit configuration and is large. As a result, the lighting voltage of the /\logen lamp changes as shown in FIG. 1 in response to fluctuations in the power supply voltage. That is, in Fig. 1, the curve It represents the power supply voltage, and the curve ■ represents the lighting voltage of the halogen lamp.
Le.

As you can see from this figure, the lighting voltage of the halogen lamp changes due to large fluctuations in the power supply voltage, resulting in uneven shading when copying flat-tone originals, etc. There was a defective force ζ.
This was done to eliminate the drawbacks of Hereinafter, this invention will be explained using drawing diagrams.

FIG. 2 is a circuit diagram of a lamp fl control device showing an embodiment of the present invention.

In Figure 2, 1 is a power supply, 2 is a /\logen lamp, and 3
4 is a choke coil, and a rectifier circuit 5 and a trigger element 6 are provided for controlling the phase of the gate of the torch 3. The trigger element 6 consists of a light emitting diode 6a and a photoreceptor 6b. 7 is a monitor transformer for power supply voltage, and a rectifier circuit 8 is installed on its secondary side.
is connected, and its output is connected to a Zener diode 9
．． Comparator 10. added to transistor 11. A zero-cross circuit A is configured by each of the above-mentioned parts 9 to 11,
At the zero-crossing point of each cycle of the AC voltage of the power supply 1, a zero-crossing pulse signal 12 is generated.

13 is Cyrisk, 14.15 is diode, 16.1
7 is a resistor, 18 is a capacitor, 19 is a resistor, 2o is a capacitor, and both are connected to a low-pass filter 2.
1 is configured. 22 is an operational amplifier, 23 is a transistor, and the above 13 to 23 form the effective value detection circuit B.
is configured and outputs a lighting voltage monitor signal 24. 25
2 is a switching transistor, and 26 is an OR circuit.

27 is a microcomputer (hereinafter referred to as microcomputer), for example, an 8-bit 1-chip type, and has an internal timer 2.
8. It is equipped with an AD converter 29 and the like. 30 is a fixing heater, and 31 is a magnification setting device. The fixing heater 30 is started by an on signal 32 issued from the microcomputer 27, and the heater temperature is input to the microcomputer 27 by a temperature detection signal 33 from a temperature sensor (not shown). Further, the microcomputer 27 generates an exposure signal 34 and a trigger signal 35. Note that symbols are omitted for those not particularly necessary for the explanation.

Next, regarding the outline of the operation, zero cross circuit A.

The lighting operation of the halogen lamp 2 and the effective value detection circuit B will be explained in this order, and the control by the microcomputer 27 will be explained using a flowchart.

First, the operation of zero cross circuit A will be described. The output of the rectifier circuit 8 connected to the secondary side of the monitor transformer 7 is applied to the inverting input terminal of the comparator 10. Comparator 1
A constant voltage divided by resistance is applied to the non-inverting input terminal of 0. Therefore, when the input voltage of the inverting input terminal becomes the same as that of the non-inverting input terminal, output is output with the zero crossing point. 11, the zero-crossing pulse signal 12 is applied to the microcomputer 27, and the microcomputer 27 issues an interrupt every time this zero-crossing pulse signal 12 is received.

The waveform shown in FIG. 3 shows the zero-crossing pulse signal 12, and corresponds to the zero-crossing point of the waveform of the power supply 1 shown by the dotted line of waveform C.

Next, the lighting operation of the halogen lamp 2 shown in FIG. 2 will be explained. When the exposure signal 34 and trigger signal 35 shown by waveforms a and d in FIG. 3 are generated from the microcomputer 27, they pass through the OR circuit 26 and are applied to the base of the transistor 25, turning on the transistor 25. Therefore, the light emitting diode 6a in the trigger element 6 emits light, and the light enters the photothyristor 6b, thereby making the photothyristor 6b conductive. therefore.

The output of the rectifier circuit 5 is applied to the gate of the triac 3, this triac 3 is turned on, and the choke coil 4 is turned on.
The voltage of the power source 1 is applied to the halogen lamp 2 through the halogen lamp 2, causing it to emit light. The shaded portion of the waveform C in FIG. 3 is the voltage waveform applied to the halogen lamp 2, and its rise coincides with the application point of the trigger signal 35 shown in the waveform d in FIG. 3. Therefore, by changing the timing of application of the trigger signal 35, the lighting voltage of the halogen lamp 2 can be changed.

Next, the effective value detection circuit B will be explained.

At the same time that the transistor 25 turns on and the light emitting diode 6a emits light, the transistor 23 becomes conductive and applies a voltage to the gate of the thyristor 13, making it conductive. Therefore, the output of the rectifier circuit 8 charges the capacitor 18 through the diode 14,15. However, since the potential on the sides of the diodes 1 and 5 is lower than that on the side of the diode 14, charging ends first, and thereafter charging is performed only from the side of the diode 14. Then, the terminal voltage of the capacitor 18 is passed through the low-pass filter 21 and sent to the microcomputer 27 by the voltage follower of the operational amplifier 22 as a lighting voltage monitor signal 2.
It is entered as 4. Here, the reason why the capacitor 18 is charged in parallel through the resistors 16 and 17 is as follows.
If the lighting voltage waveform of the halogen lamp 2 on the secondary side of the monitor transformer 7 is integrated by one CR circuit, the average value will be detected, and if this is used as the effective value detection, the phase angle of the lighting voltage of the halogen lamp 2 will be However, a non-negligible error occurs, and the voltage cannot be used as the lighting voltage for the halogen lamp 2. For this purpose, by selecting appropriate values for the resistors 16 and 17 and charging the capacitor 18, the effective value of the lighting voltage of the halogen lamp 2 is approximately detected.

In this way, an interrupt is performed every time the zero-cross pulse signal 12 is input to the microcomputer 27, and the effective value of the voltage at the sampling point S as shown in the waveform e in FIG. It is input to the microcomputer 27 as . The timing of application of the trigger signal 35 is controlled by the microcomputer 27 so that the voltage monitored by the lighting voltage monitor signal 24 matches the target value.

Next, phase control by the microcomputer 27 will be explained with reference to flowcharts shown in FIGS. 4 and 5(a) to (c). Note that (1), (2), . . . groups represent each step, and F represents a flag.

FIG. 4 is a flowchart of an external interrupt using the zero-crossing pulse signal 12.

First, the internal timer 28 for phase control reference is started (1), then the lighting voltage monitor signal 24 is A/D converted by the AD converter 29 (2), and stored in the memory (3). 4). If the ON flag is set, turn on the fixing heater 30 (5).

5(a) to 5(C) show an internal timer interrupt routine by the internal timer 28. FIG. The explanation will be given below in order starting from FIG. 5(a).

First, stop the internal timer 28 (11), determine whether the halogen lamp 2 is ON (12), and if YES, raise the trigger signal 35 (13), and when 2004 seconds have elapsed by the microcomputer 27 (14), raise it (15).
, outputs a trigger pulse with a width of 200 JLs. At this time,
If the trigger signal 35 and the exposure signal 34 are input at the same time, the halogen lamp 2 lights up as already explained.

In the next step, we check restart F (1
6), restart F is copy 2 when executing multi-copy.
This flag is necessary for exposing the original after the first sheet, and if this flag is set, the restart F will be reset17).
If soft start F is not set (18), the final phase angle of the previous document exposure and the ON and OFF of the fixing heater 30
Refer to F status 18), the current fixing heater 30 is ON.
, if the two match by comparing the OFF states (2o), a trigger signal 35 is generated to start lighting the halogen lamp 2 according to the final phase angle of the previous document exposure (21); are different, and the fixing heater 30
is currently OFF compared to the ON state at the end of the previous exposure state.
If the fuser is in the OFF state, the phase angle is increased by 1001Ls using the internal timer 28 (22), the state of the fixing heater 30 is checked 23), and the OFF state is changed to the ON state in the same way. internal timer 2 if
8 reduces the phase angle by 200 S (24).

By steps (18) to (24), the fixing heater 30
The phase angle is corrected in advance based on the ON/OFF state of the fixing heater 30 to compensate for the voltage drop in the power supply 1 due to the ON/OFF state transition of the fixing heater 30.

However, during the soft start in step (18), the process shifts to control (2) in FIG. 5(b). In addition, if the ON command F of the halogen lamp 2 is not set at the beginning of the internal interrupt routine, it is determined whether or not copying is currently in progress (2
5) If copying is in progress, reset the phase angle calculation F (26), set the restart F (27), and turn off the exposure signal 34 (28). On the other hand, if copying is not in progress, reset the restart F to prepare for the next copy, set the soft start F, set the internal timer 28 to 4 ms (28), and turn off the exposure signal 34 (28). ). Note that internal timer 2 is set in step (28).
The reason why 8 is set to 4 ms is because it is a necessary setting value to interrupt the internal interrupt routine.

Next, the (2) routine to which the routine moves in step (18) will be explained with reference to FIG. 5(b).

First, the setting level Hn (8 bits) which is the target value of the lighting voltage of the halogen lamp 2 and the AD of the AD converter 29 are set.
Find the subtraction value N from the conversion value ADn (8 bits) (31)
, by determining whether the subtraction value N is positive or negative (32), and if it is less than or equal to the subtraction value O, the lamp voltage match F and lamp voltage over F are reset and set, respectively (33).

Next, check the soft start F (34), and when the soft start F is set, set the internal timer 28 to 7.
Set it to ms35), reset the heater off switch F, heater on switch F2, phase angle calculation F, respectively.36)
, the fixing heater 30 is turned on.

Check the OFF state (37), and if it is ON, set the heater memory F (3θ), and if it is OFF, reset the heater memory F (3 days).

The heater off switching F and heater on switching F shown in step (36) are performed when the fixing heater 30 is turned on while the halogen lamp 2 is on.
This is a flag that is set by switching ON and OFF.

Also, if soft start F is not set in step (34), check F during soft start (40).
If F is standing during soft start, check whether the lamp voltage is over F (41), reset F during soft start (42), and end the soft start. Now, in this example, since the microcontroller 27 is 8 bits,
Since 2B=256 bits can be used for the setting level Hn, the setting value will be indicated by LSB. For example 40L
SB indicates the division point of 407256. On the other hand, if the lamp voltage over F is not set (43), if the value of the subtraction value N is less than 40LSB (43), set the internal timer 28 smaller by 51LS (45), if the subtraction value N≧40LSB. In this case, the internal timer 28 is set in increments of 40 p-s (44). That is, the speed of the soft start F is switched when the subtraction value N, which is the difference between the AD conversion value ADn and the set level Hn for the halogen lamp 2, reaches 40LSB. Here, in this invention, 200LSB is input at the dividing point from the lower level to the set level H.
Since n is set as (200-40)/200 (LSB), that is, the soft start is switched at 80% of the set voltage level of the halogen lamp 2.

Further, in step (32), when the set level Hn and the AD conversion value ADn match, the lamp voltage match F is set, the lamp voltage over F is reset, and the process returns to step (30).Meanwhile, If the set level Hn is positive in the comparison in step (32), the lamp voltage match F and lamp voltage over F should be reset.
) Hetobu.

Next, the (2) routine to which the routine moves in step (40) will be explained with reference to FIG. 5(C).

First, the heater on switch F and heater off switch F are checked (51) and (52). When the heater on switch F is on, subtract 200 JLS from the internal timer 28 to 53.
), internal timer 2 when heater off switch F is set.
8 is added by 1001Ls (54). This step (5
3) The fixing heater 30 is turned on by (54).

Consider voltage drop due to OFF state. On the other hand, if both the heater-off switching F and heater-on switching flags are not set, check the phase angle calculation flag.
), when this flag is not set, set the phase angle calculation flag (5B) and control the next half wave with the same phase as the previous half wave, and when the phase angle calculation flag is set , calculate the phase angle of the next half wave using the subtraction value N obtained in step (31), and calculate the phase angle of the next half wave once per cycle of the power supply frequency.
＼Change the phase angle so that the lighting voltage of the rogen lamp matches the input setting voltage.

First, check the lamp voltage match F57). When this flag is set, the phase angle is not changed and the next cycle is controlled using the same phase angle as the previous cycle.
If the lamp voltage match F is not set, check the lamp voltage over F58). When this flag is set, the lamp voltage is higher than the set level Hn, so the internal timer 28 is set according to the value of the subtraction value N. Set the set value to be larger than the value controlled for the previous cycle (59
) ~ (67). On the other hand, when the voltage over F is not set, the lamp voltage is smaller than the set level Hn, so the set value of the internal timer 28 is set smaller than the value controlled for the previous cycle (68) to (76). ). Through these steps (59) to (87) and (as) to (76), the correction constant is changed according to the value of the subtraction value N, and the lighting voltage of the halogen lamp is quickly converged to the set level Hn. I can do it.

Next, temperature control of the fixing heater 30 related to phase control of the halogen lamp 2 will be explained with reference to the drawings.

FIG. 6 is a flowchart of temperature control of the fixing heater 30. In addition, (81), (82),...
represents each step, and F represents a flag.

7A to 7D are control waveform diagrams of the halogen lamp 2, the lighting voltage monitor signal 249, the phase angle calculation F, and the fixing heater 30. The flowchart shown in FIG. 6 will be explained below with reference to FIG.

After the power is turned on, when the roller surface temperature Lt reaches 180 ("C), WAIT-U P L (81), WAIT-U
After P, Lt<180(
Turn on the fixing heater 30 when the temperature is 92), (9
5), (82), If the roller surface temperature Lt reaches 180 ('O) 1 second after the heater is turned on, the fixing heater 30 is turned off (87), (88).

(8B), (130). On the other hand, if the roller surface temperature Lt reaches 180 ('C) after 1 second, the fixing heater 30 is kept on for 1 second until LL = 180 ('C). 81).

In addition, the roller surface temperature Lt is detected again by the temperature detection signal 33 of the fixing heater 30 after one second while the fixing heater 30 is in the off state, and if Lt<180 ('C), the fixing heater 3 is again detected.
0 is turned on (83), (84).

Then, by steps (83) to (88), the fixing heater 3
Depending on the temperature condition, either ON or OFF control of 0 is continued for at least 1 second.

When the halogen lamp 2 is on, the fixing heater 30 is on,
Since switching OFF greatly affects the lighting voltage of the /\logen lamp, switching of the fixing heater 30 is prohibited during soft start (86), and switching of the fixing heater 3o is only performed when phase angle calculation F is set (97). are permitted as necessary. As shown in FIG. 7, switching of the fixing heater 30 is permitted only when the phase angle calculation F is set in step (87).
Since the sampling point S is every cycle as described above, if the fixing heater 30 is turned on at the timing shown in FIG. By sampling, it is possible to monitor the lighting voltage monitor signal 24 including the influence of turning on the fixing heater 30, and it is possible to determine the phase angle=3 for the next cycle. For example, when the fixing heater 30 is turned on at point X, the phase angle α3 of the next cycle does not include the effect of the fixing heater 30 being turned on, and the convergence of the lighting voltage of the halogen lamp 2 is delayed by one cycle. Here, 1
The reason why the lighting voltage monitor signal 24 is sampled every cycle is that if there is a difference in the distortion of the upper half-wave and the lower half-wave of the commercial power supply, the lighting voltage monitor signal 24 is sampled in one half-wave. This is because it is possible to control with higher precision by detecting.

FIG. 8 is a waveform diagram of the main part to explain the sequence in the case of two copying, (a) F during tt copying, (b) exposure signal 34, (c) (one copy signal 35, (d)
is the lighting waveform of l\logen lamp 2, and indicates that soft start lighting ST is performed only at the beginning of the first copy.

Next, a measurement example in which phase control is performed based on the present invention will be described with reference to FIGS. 9 and 10.

FIG. 9 is a graph showing the relationship between the power supply voltage and the change in the amount of light of the halogen lamp, where the curve I shows the power supply voltage and the curve ■ shows the change in the amount of light.

FIG. 10 is a response characteristic diagram of the power supply voltage versus the lighting voltage of the /\Rogen lamp, where (a) shows the lighting voltage of the /\Rogen lamp 2, and (b) the voltage of the power supply 1.

As can be seen from FIG. 9, the variation in the light amount of the halogen lamp 2 was suppressed to 4% with respect to the voltage variation of ±10% with respect to the voltage AC1oov of the power source 1.

Also, as shown in Fig. 10, the voltage of power supply 1 is AC10
The response time of the voltage of the halogen lamp 2 to a voltage fluctuation of ±10% with respect to 0V quickly converges at 700 m5.

As explained in detail above, the present invention stores the phase control angle at the end of exposure scanned every time a plurality of copies are made at the same time using a microcomputer, and uses this memorized phase control angle at the beginning of the next document scan. Since the phase control angle is used as the phase control angle, the phase control angle can be started from an appropriate value.
Therefore, the lighting voltage can quickly converge to the target value.
Moreover, the life of the lamp can be extended.

In addition, phase control of the lamp lighting voltage can be realized using a microcomputer and a simple electric circuit, making it possible to achieve phase control of the lamp lighting voltage using a microcomputer and a simple electric circuit.
Compared to R), it has the advantage of being significantly improved in terms of cost and also being able to be made smaller.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram of fluctuations in input voltage versus lighting voltage of a halogen lamp, Fig. 2 is a circuit diagram of a lamp control device showing an embodiment of the present invention, and Fig. 3 is an explanation of the operation of the embodiment of Fig. 2. Figure 4 is an external interrupt flowchart,
Figures 5(a) to (C) are diagrams showing the internal timer interrupt routine, Figure 6 is the temperature control flowchart 1, Figure 7 is a control waveform diagram, and Figure 8 is the main points for copying two sheets. FIG. 9 is a diagram showing the relationship between the input voltage and the lighting voltage of the halogen lamp, and FIG. 10 is a response characteristic diagram of the input voltage versus the lighting voltage of the halogen lamp. In the figure, 1 is a power supply, 2 is a halogen lamp, 3 is a triac, 4 is a choke coil, 5 and 8 are rectifier circuits, 6 is a trigger element, 7 is a monitor transformer, 9 is a Zener diode, 10 is a comparator, 11° is a capacitor, 21 is a low-pass filter, 22 is an operational amplifier, 24 is a lighting voltage monitor signal, 26 is an OR circuit, 27 is a microcomputer, 28 is an internal timer, 29 is an AD converter, 3o is a fixing heater, 31
is a magnification setting device, 32 is an on signal, 33 is a temperature detection signal,
34 is an exposure signal, 35 is a trigger signal, A is a zero cross circuit, and B is an actual value detection circuit.

Claims (1)

[Claims] In a lamp control device in which the lighting voltage of a lamp is controlled by a microcomputer, the microcomputer stores the phase control angle at the final time of exposure that is scanned every time a plurality of copies are scanned at the same time, and the stored phase control angle is A lamp control device comprising means for lighting the lamp using the angle as an initial phase control angle for the next document scan.