JPS6039664A - lamp control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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, power control for the halogen lamp used in the original exposure lamp of a copying machine has been done using a lamp regulator (which has a complex circuit configuration and is large in size. The voltage fluctuates as shown in Fig. 1. That is, in Fig. 1, curve I shows the power supply voltage, and curve 2 shows the lighting voltage of the halogen lamp.

As you can see from this figure, the lighting voltage of the halogen lamp changes due to large fluctuations in the power supply voltage.
When copying halftone originals, etc., there is a drawback that uneven shading appears in the finished product.

The present invention is directed to the above-mentioned conventional lamp regulator (CV R
) was developed to eliminate the drawbacks of below,
This invention will be explained with reference to the drawings.

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

In FIG. 2, 1 is a power source, 2 is a halogen lamp, 3 is a triac, and 4 is a choke coil. A gas element 6 for controlling the phase of the gate of the triac 3 is composed of a light emitting diode 6a and a photothyristor 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. 3-0 is a fixing heater, and 31 is a magnification setting device. The fixing heater 30 starts with an on signal 32 issued from the microcomputer 27.
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 torch 3, which turns on, and the voltage of the power source 1 is applied to the halogen lamp 2 via the choke coil 4, 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 diode 15 side is lower than that on the diode 14 side,
Charging is completed first, and thereafter charging is performed only from the diode 14 side. Then, the terminal voltage of the capacitor 18 is passed through a low-pass filter 21 to a voltage follower of an operational amplifier 22 and sent to a microcomputer 27 as a lighting voltage monitor signal 24.
is entered as . Here, the reason why the capacitor 18 is charged in parallel through the resistors 16 and 17 is because the lighting voltage waveform of the halogen lamp 2 on the secondary side of the monitor transformer 7 is integrated by one CR circuit. This is an average value detection, and if this is used as an effective value detection, a non-negligible error will occur in the phase angle of the lighting voltage of the halogen lamp 2, and it cannot be used as the lighting voltage of 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 using flowcharts shown in FIGS. 4 and 5(a) to (C). Note that (+), (2), . . . 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), judge whether the halogen lamp 2 is ON or not (12), and if YES, raise the trigger signal 35 (13). When 200 ILs have elapsed by the microcomputer 27 (14), raise the trigger signal 35 (15).
), outputs a trigger pulse with a width of 200g5. 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 the soft start F is not set (18), the final phase angle of the previous original exposure and the ON, OF of the fixing heater 3o
Refer to F status 18), the current fixing heater 30 is ON.
, if the two match by comparing the OFF states (20), 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.
When the phase angle is changed to L (22), the internal timer 28 increases the phase angle by 100 L (22).
Check the state of 023). Similarly, if the state has changed from the OFF state to the ON state, the internal timer 28 reduces the phase angle by 2001Ls (24), and steps (18) to (24) 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 (2B), set the restart F (27), and turn off the exposure signal 34 (29). 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 routine ① to which the routine moves in step (18) will be explained with reference to FIG. 5(b).

First, set the target value of the lighting voltage of the halogen lamp 2: /bell Hn (8 bits) and the A of the AD converter 29.
Find the subtraction value N from the D conversion value ADn (8 bits) (31
), and by determining whether the subtraction value N is positive or negative (32), if it is less than the subtraction value O, the lamp voltage matches F and the lamp voltage exceeds 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.
m s (35), heater off switch F, heater on switch F2, phase angle calculation F, respectively.
6) Turn on the fixing heater 3o.

Check the OFF state (37), and if it is ON, set the heater memory F (39), and if it is OFF, reset the heater memory F (38).

The heater off switch IF and the heater on switch F shown in step (36) are
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 (41), and if the value of the subtraction value N is less than 40LSB (43), the internal timer 28 should be set smaller by 51LS (45), so that the subtraction value N≧40LSB. In this case, the internal timer 28 is set in small increments of 40 ps (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 40 LSB. 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 goes to step (34). On the other hand, if the set level Hn is positive in the comparison in step (32), reset the lamp voltage -@F and lamp voltage over F)L (48), step (3).
4) 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 the heater off switch F are checked (51) and (52). When heater on switch F is on, subtract 200pLS from internal timer 2853)
, when the heater off switch F is set, the internal timer 28
Add 100g5 to (54). This step (53)
, (54) turns on the fixing heater 30.

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 (56) and control the next half wave with the same phase as the previous half wave, and when the phase angle calculation flag is set calculates the phase angle of the next half wave using the subtraction value N obtained in step (31), and changes the phase angle so that the lighting voltage of the halogen lamp matches the input setting voltage once per power frequency cycle. do.

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 (58
) ~ (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 (88) to (7B). ). Through steps (58) to (87) and (ee) 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 3o. Note that (81), (82), . . . represent each step, and F represents a flag.

7A to 7D are control waveform diagrams of the halogen lamp 2, the lighting voltage monitor signal 241, 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 turning on the power, when the roller surface temperature Lt reaches 18° CO), WAIT-UPL (81), and after WAIT/UP,
Roller surface temperature Lt except when halogen lamp 2 is on
In order to keep 180 ('O), Lt <, 180 (
'O) (7) Turn on the fixing heater 30 when f12)
, (95), (82), If the roller surface temperature Lt reaches 180 ('C) 1 second after the heater is turned on, the fixing heater 3o is turned off (87), (88).

(8!3), (flo). On the other hand, if the roller surface temperature Lt WAIT-UP to 180 ('O) after 1 second and lz' is not reached, the fixing heater 30 is kept on for 1 second until Lt = 180 ('0) ( 81).

Furthermore, after one second while the fixing heater 3o is off, the roller surface temperature Lt is detected again using the temperature detection signal 33 of the fixing heater 3o, and if Lt < 180 ('O) (7), the fixing heater 3o is turned on again. (83), (84).

(85), (8fl), while Lt, >180 ('
O) (7) Sometimes, the fixing heater 3o is kept off until Lt<180('O). This step (8
2) to (91) and (83) to (86), the ON/OFF control of the fixing heater 3° is continued for at least 1 second depending on the temperature condition.

When the halogen lamp 2 is on, the fixing heater 3o is on,
Since the OFF switching greatly affects the lighting voltage of the halogen lamp, the fixing heater 3 is
Switching of the fixing heater 3o is prohibited, and switching of the fixing heater 3o is permitted as necessary only when the phase self-operation and calculation F are set (87). As shown in FIG. 7, switching of the fixing heater 30 is permitted only when the phase angle calculation F is set in the stepper (87).
Since the sampling point S of No. 4 is every cycle as described above, if the fixing heater 3° is turned on at the timing shown in FIG. 8, the next sampling point S (at point X)
If the lighting voltage monitor signal 24 is sampled at , the lighting voltage monitor signal 24 including the influence of turning on the fixing heater 3o can be monitored, and the phase angle α3 of the next cycle can be determined. For example, when the fixing heater 3o is turned on at point X, the phase angle α3 of the next cycle does not include the effect of the fixing heater 3o being turned on, and the convergence of the lighting voltage of the halogen lamp 2 is delayed by one cycle. here,
The reason why the lighting voltage monitor signal 24 is sampled every cycle is that when there is a difference in the distortion between the upper half wave and the lower half wave of the commercial power supply, the lighting voltage monitor signal 24 is sampled in either 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 case of two copying, (a) is F during copying, (b) is exposure signal 34, (C) is trigger signal 35, (d) is the lighting waveform of the halogen lamp 2, which indicates that the 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 correspondence between the power supply voltage and the change in the amount of light of the halogen lamp, where the curve ``■'' represents the power supply voltage and the curve ``■'' represents the change in the amount of light.

Figure 1O is a response characteristic diagram of the power supply voltage versus the lighting voltage of the halogen lamp, where (a) shows the lighting voltage of the halogen lamp 2;
(b) shows 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 of AC 100V of the power source 1.

Also, as shown in Figure 1O, 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 described above in detail, the present invention controls the phase of the power supply voltage according to the transient state of the fixing heater that affects power supply voltage fluctuations, so that power can be stably supplied to the lamp.
And the soft start mechanism can extend the life of the lamp.

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 the drawing]

Fig. 1 is a variation characteristic diagram of input voltage versus lighting voltage of a halogen lamp, Fig. 2 is a circuit diagram of a Rajp 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 a flowchart of temperature control, Figure 7 is a control waveform diagram, and Figure 8 is the waveform of the main part in the case of two-sheet copying. figure,
FIG. 9 is a correspondence diagram of the variation in input voltage versus 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, 5.8 is a rectifier circuit, 6 is a trigger element, 7 is a monitor transformer, 9 is a Zener diode, 10 is a comparator, 11° 23.25 is a transistor, 1
2 is a zero cross pulse signal, 13 is a cyrisk, 14.
15 is a diode, 16, 17.19 is a resistor, 18.
20 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, 30 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, A1 is a zero cross circuit, and B is an effective value detection circuit. Warm-/2j'/4

Claims (1)

[Claims] A lamp control device that controls the lighting voltage of a lamp by a microcomputer includes means for detecting the effective value of the lighting voltage of the lamp, a lighting voltage monitor signal obtained by A/D converting the effective value of the lighting voltage with an AD converter, and a lighting voltage monitor signal of the lamp. 1. A lamp control device, comprising means for comparing the comparison value with a set level, and controlling the phase control angle of the lamp by the microcomputer according to the comparison value.