JP4203660B2 - High pressure discharge lamp lighting device and image display device - Google Patents

Description

  The present invention relates to a high pressure discharge lamp lighting device suitable for a light source of a projector and an image display device using the same.

FIG. 18 shows a schematic configuration of a conventional projector. The light output from the high pressure discharge lamp 1 lit by the high pressure discharge lamp lighting device 4 is collected by the lens 5, and the light transmitted through the rotating color filter 6 passes through the lens 7 to the image display element 8 called DMD. The reflected light is projected onto a screen (not shown) via the projection lens 9. Here, DMD (digital micromirror device) is an element in which hundreds of thousands to millions of mirrors that move independently on a CMOS semiconductor are spread out. An image can be displayed. As the rotating color filter 6 rotates, the light applied to the DMD 8 is switched to R (red), G (green), B (blue), and W (white). Therefore, the control circuit 10 on the set side is synchronized with this. By applying image signals of three primary colors and luminance to the DMD 8, it is possible to project a color image on the screen. This system is known as the DLP ^™ system. Here, DLP ^™ is a trademark of Texas Instruments Incorporated.

Conventionally, when a high-pressure discharge lamp for direct current lighting is used as a light source of a projector, a method of superimposing a pulse current on a direct current lamp current (Japanese Patent Laid-Open No. 2003-272879) is used to suppress arc jump. In the case of a projector using liquid crystal, there is no problem even if a pulse current is generated periodically, but it is necessary to devise in order to implement it with a DLP ^™ system projector using DMD. In the DLP ^TM system, as described above, light is projected onto the rotating color filter 6 and the projected light is applied to the DMD 8 to output an image. Therefore, a pulse current is periodically generated in the DC lamp current. However, depending on the timing at which the pulse current is generated, the projected image may flicker. Therefore, it is necessary to synchronize the rotation of the color filter 6 and the generation timing of the pulse current, and a pulse superimposed signal is input from the control circuit 10 on the set side of the projector to the high pressure discharge lamp lighting device 4 to output the pulse current. Is common.

  There are two possible synchronization methods: the trigger method (FIG. 19) and the synchronization method (FIG. 20). In the figure, the horizontal axis represents the passage of time. In any method, the color of the color filter is changed over time as B → W → R → G → B → W →... At the timing of W (white) on the set side of the projector. A pulse superposition signal is input from the control circuit 10 to the high pressure discharge lamp lighting device 4 and the pulse current is superimposed on the DC lamp current.

  As shown in FIG. 19, in the trigger method, a trigger signal at a timing for generating a pulse current is input to the high-pressure discharge lamp lighting device 4 from the set-side control circuit 10, and the high-pressure discharge lamp lighting device 4 receives the trigger signal. Thus, a pulse current is generated for a certain time.

As shown in FIG. 20, the synchronization method inputs the timing and time for generating the pulse current from the control circuit 10 on the set side to the high pressure discharge lamp lighting device 4, and the high pressure discharge lamp lighting device 4 receives the signal, This is a method of generating a pulse current.
JP 2003-272879 A

Considering the case where the rotation speed of the color filter is changed during the development of the projector set, in the case of the trigger method (FIG. 19), it is necessary to change the pulse superposition time due to the change of the rotation speed. Come on. Since the pulse superposition time is set in the high pressure discharge lamp lighting device, not only the design change of the pulse superposition signal on the set side but also the design change of the pulse superposition time of the high pressure discharge lamp lighting device is necessary, which greatly improves the development efficiency. descend. For synchronization method compared to that (FIG. 20), even under development by even rotational speed of a color filter is changed, since it is sufficient only design change of the pulse superposition signal of the set side, the pulse current superposition projector DLP ^TM system It is preferable to adopt a synchronous method.

  However, when the monitor signal connector is inserted or removed, the pulse superimposed signal may become unstable as shown in FIG. In this case, a constant power (effective value) should be maintained on the premise that the pulse current is ON / OFF at a constant cycle, but when an unstable pulse superimposed signal is input as shown in FIG. The power supplied to the discharge lamp and the power output from the high-pressure discharge lamp lighting device are significantly increased, which may cause wear or damage to the electrodes of the discharge lamp or failure of the discharge lamp lighting device itself.

Therefore, the present invention limits the power supplied to the discharge lamp when any pulse superimposed signal is input when generating a pulse current in a synchronous manner in a high pressure discharge lamp lighting device mounted on a projector of the DLP ^TM system. It is another object of the present invention to provide a high pressure discharge lamp lighting device capable of preventing electrode wear and damage of the discharge lamp or failure of the high pressure discharge lamp lighting device itself.

According to the present invention, in order to solve the above-described problem, a high-pressure discharge lamp lighting device that supplies a DC lamp current to light a high-pressure discharge lamp, and when the pulse superimposed signal is in the first state, the second In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal by increasing the lamp current as compared with the state of the above, the time during which the pulse superimposition signal is in the first state is limited When the time is exceeded, the pulse current is not superimposed in synchronization with the pulse superimposed signal for a predetermined time .

  According to the present invention, in a high-pressure discharge lamp lighting device that lights a discharge lamp with a direct current, when a pulse current is generated in synchronization with a pulse superimposed signal given from the outside, any pulse superimposed signal is input. Even so, there is an effect that by limiting the pulse superposition time, the power supplied to the discharge lamp can be limited to prevent electrode wear or damage of the discharge lamp or failure of the high pressure discharge lamp lighting device itself.

  FIG. 1 shows a circuit configuration of a preferred embodiment of the present invention. The DC power source E outputs a DC voltage obtained by rectifying and smoothing a commercial AC power source. A series circuit of a switching element Q1, a chopper inductor L1, a smoothing capacitor C1, and a current detection resistor R1 is connected to both ends of the DC power supply E. A diode D1 for energizing regenerative current is connected to the series circuit of the chopper inductor L1 and the smoothing capacitor C1. The switching element Q1 is driven on / off at a high frequency by the output of the PWM control circuit 2. When the switching element Q1 is on, a current Ichop that gradually increases flows from the DC power source E via the switching element Q1, the chopper inductor L1, the smoothing capacitor C1, and the current detection resistor R1. This current I chop is detected as a voltage across the resistor R 1 and input to the PWM control circuit 2.

  The PWM control circuit 2 compares the detection voltage of the chopper current Ichop with the reference voltage Vref, and when the detection voltage proportional to the gradually increasing chopper current Ichop reaches the reference voltage Vref, the switching element Q1 is turned off. When the switching element Q1 is turned off, the regenerative current due to the energy stored in the chopper inductor L1 flows through the path of the inductor L1, the smoothing capacitor C1, the diode D1, and the inductor L1, and the stored energy of the inductor L1 is released. This regenerative current flows as a gradually decreasing current. Usually, a secondary winding (not shown) is added to the chopper inductor L1, and the PWM control circuit 2 detects the timing when the output of the secondary winding becomes zero, thereby reducing the regenerative current to zero. It is detected that the switching element Q1 is turned on, and the switching element Q1 is turned on again.

  The DC voltage obtained at the smoothing capacitor C1 is applied to the parallel circuit of the high-pressure discharge lamp 1 and the capacitor C2 via the inductor L2. The inductor L2 and the capacitor C2 constitute a low-pass filter, which removes the high-frequency ripple current due to the above-mentioned chopper operation and supplies the high-pressure discharge lamp 1 with a stable DC current.

  The DC voltage obtained at the smoothing capacitor C1 can be regarded as substantially representing the lamp voltage Vla of the discharge lamp 1, and this is divided by resistors R2 and R3 to provide a microcomputer (for example, M37540M4 manufactured by Renesas). To the A / D conversion input terminal a. This microcomputer 3 has a built-in A / D conversion circuit, converts the divided voltage input to the A / D conversion input terminal a into a digital value, and grasps the voltage corresponding to the lamp voltage Vla of the discharge lamp 1. Then, it operates so as to apply the reference voltage Vref to the PWM control circuit 2 so as to obtain the lamp power corresponding thereto.

  Here, in order to supply the analog reference voltage Vref from the microcomputer 3 to the PWM control circuit 2, a microcomputer having a D / A conversion output may be used. However, since the microcomputer becomes expensive, in this embodiment, 2 The analog reference voltage Vref is generated by outputting a duty signal from the value output port and averaging by a CR integration circuit.

  The terminal B is a binary output port for outputting a power command value, and outputs a duty signal that is alternately switched between an H level (microcomputer power supply voltage level) and an L level (microcomputer ground voltage level) at a high frequency. The ratio of the H level period in one cycle of the duty signal is variable according to the magnitude of the reference voltage Vref to be applied to the PWM control circuit 2. The time constant of the CR integration circuit composed of the series circuit of the resistor R4 and the capacitor C3 connected to the binary output terminal B is set sufficiently larger than the cycle of the duty signal, and the duty signal is averaged by this. Converted to analog DC voltage.

  On the other hand, the terminal A is a binary output port for outputting a pulse current superimposed signal, which outputs an H level (microcomputer power supply voltage level) at the timing when the pulse current is superimposed, and at an L level when the pulse current is not superimposed (Microcomputer ground voltage level) is output. In the figure, the H-level pulse superimposed signal output intermittently from the terminal A is denoted as IlaUP. When the pulse superimposed signal IlaUP is output, PWM control is performed using a potential obtained by dividing the potential of the terminal A at the H level (the power supply voltage level of the microcomputer) and the potential of the capacitor C3 by the resistor R6, the diode D2, and the resistor R5 as the reference voltage Vref. Input to the circuit 2. Further, when the pulse superimposed signal IlaUP is not output, the diode D2 is cut off, so that when viewed from the PWM control circuit 2, it is the same as the resistor R6 and the terminal A, and the potential of the capacitor C3 is directly passed through the resistor R5. The reference voltage Vref is input to the PWM control circuit 2.

  Although the details of the internal configuration of the PWM control circuit 2 are not shown, for example, the reference voltage Vref is input to one input terminal of the comparator with high input impedance, and the detection voltage of the chopper current Ichop is input to the other input terminal. When the condition of (Ichop detection voltage)> Vref is satisfied, the flip-flop is reset by the output of the comparator. This flip-flop is set at the time of zero crossing of the regenerative current of the inductor L1, and the switching element Q1 is turned on / off by the output of this flip-flop. Of course, the configuration of the PWM control circuit 2 is not limited to this. Further, the configuration for controlling the direct current of the discharge lamp 1 is not limited to that illustrated in FIG. 1. In short, any configuration is possible as long as a pulse current can be superimposed on the direct current lamp current.

  As described above, the microcomputer 3 of this embodiment includes one A / D conversion input terminal a and two binary output terminals A and B, but in addition to this, three binary input terminals. b, c, d are provided. These input terminals b, c, and d are terminals for inputting a lamp lighting signal, a pulse selection signal, and a pulse superimposition signal given from the set side of the projector, and in order to ensure insulation, a photo is input to the input stage. It has a coupler.

  When the lamp lighting signal LS is inputted from the set side, the light emitting element of the photocoupler generates an optical signal via the resistor R101, and this is received by the light receiving element of the photocoupler, thereby short-circuiting both ends of the resistor R103. The input terminal b is pulled down to the ground level. When the lamp lighting signal LS is not input, the light receiving element of the photocoupler has a high impedance, so that the input terminal b has a voltage obtained by dividing the power supply voltage Vcc by the resistors R102 and R103. Accordingly, it is determined that the lamp is OFF when the input terminal b is at the H level and that the lamp is ON when the input terminal b is at the L level.

The other input terminals c and d have the same configuration, and a pulse selection signal supplied from the set side is input to the input terminal c via a signal input circuit including resistors R104, R105, and R106 and a photocoupler. When the input terminal c is at the H level, a synchronized pulse is selected, and when the input terminal c is at the L level, a periodic pulse is selected. A pulse superimposed signal PS supplied from the set side is input to the input terminal d via a signal input circuit composed of resistors R107, R108, R109 and a photocoupler. When the input terminal d is at the H level, a pulse is input. When not generated and at L level, a pulse generation command is received. When the pulse superimposed signal PS supplied from the set side is normal, the time when the input terminal d becomes H level and the time when it becomes L level is a predetermined ratio.

  In the microcomputer 3, the lamp lighting signal, the pulse selection signal, the pulse superimposed signal from the set side inputted from these binary input terminals b, c, d, and the lamp voltage Vla inputted to the A / D conversion input terminal a. Based on the detected value, either the H / L output of the binary output terminal A and the duty signal of the binary output terminal B are controlled.

  When the pulse current is superimposed on the lamp current by the pulse superimposed signal, the microcomputer 3 determines the state based on the H level / L level of the pulse superimposed signal, and outputs the pulse current superimposed signal IlaUP at a timing synchronized with the signal. By doing so, the reference voltage Vref for power control is increased at that timing, and a pulse current is supplied to the discharge lamp. This operation is shown in FIG.

In addition, when the pulse current is periodically superimposed on the lamp current, a timer function or the like is used inside the microcomputer so that the pulse current superimposed signal IlaUP is output at an appropriate time and the pulse current is superimposed on the lamp current.
Hereinafter, the control program and operation waveforms will be described in detail with specific examples.

Example 1
FIG. 3 is a flowchart showing the operation of the first embodiment of the present invention, and shows a program for discriminating pulse superposition in the microcomputer 3 of FIG. In this embodiment, the pulse current is superimposed on the lamp current in synchronization with ON / OFF of the pulse superimposed signal, and a predetermined time limit t1 is provided for the ON time of the pulse superimposed current, and the pulse current is generated for a longer time. It is characterized by not.

  The microcomputer 3 periodically executes the flow of FIG. 3 by timer interruption. In step # 1, the state of the pulse superimposed signal is determined. If the pulse superimposed signal is at H level, the process proceeds to steps # 2 and # 3 to generate a pulse. If the pulse superimposed signal is at the L level, the process proceeds to step # 4 in order to end the pulse generation. In step # 2, it is determined whether or not the elapsed time since the start of pulse superposition has exceeded a predetermined time limit t1. If the elapsed time from the start of pulse superposition exceeds a predetermined limit time t1, the process proceeds from step # 2 to step # 4, and the pulse current superposition signal output is set to L level. That is, even when the pulse superimposed signal is at the H level, it can be determined that the normal pulse superimposed signal is not input when the duration of the H level exceeds the predetermined limit time t1, The current superimposed signal output is forcibly set to L level. If the elapsed time from the start of pulse superposition does not exceed the predetermined time limit t1, the process proceeds from step # 2 to step # 3, and the pulse current superposition signal output is set to H level.

  FIG. 4 is a waveform diagram for explaining the operation of this embodiment. As shown in the figure, when the pulse superimposition signal is turned ON, the pulse current is superimposed on the lamp current during that period. However, when the period during which the pulse superimposition signal is ON exceeds a predetermined ON limit time t1, the superimposition of the pulse current on the lamp current is forcibly released. Thereby, the electric power supplied to the discharge lamp 1 is limited, and electrode wear and damage of the discharge lamp 1 or a failure of the high-pressure discharge lamp lighting device 4 itself can be prevented.

  In Example 1, in order to realize the means for counting the elapsed time from the start of pulse superposition in the microcomputer 3, for example, when the pulse current superposition signal output changes from L level to H level, There is a means of resetting the count value of the elapsed time since the start of pulse superposition and counting up the count value every time step # 3 in FIG. 3 is executed.

(Example 2)
FIG. 5 is a flowchart showing the operation of the second embodiment of the present invention, and shows a program for discriminating pulse superposition in the microcomputer 3 of FIG. In this embodiment, the pulse current is superimposed on the lamp current in synchronization with ON / OFF of the pulse superimposed signal, and a predetermined time limit T1 is provided for the OFF time of the pulse superimposed current.

  The microcomputer periodically executes the flow of FIG. 5 by timer interruption. In step # 1, the state of the pulse superimposed signal is determined. If the pulse superimposed signal is at the L level, the process proceeds to steps # 2 and # 3 in order to end the pulse generation. In step # 2, it is determined whether or not the elapsed time after the completion of the pulse superposition has exceeded a predetermined time limit T1. If the elapsed time after completing the pulse superposition exceeds the predetermined time limit T1, the process proceeds from step # 2 to step # 5. In step # 5, when the pulse superimposed signal is at the L level, the L level duration exceeds the predetermined time limit T1, and no normal pulse superimposed signal is input. Process (for example, display a warning) or do nothing. If the elapsed time after the completion of the pulse superposition does not exceed the predetermined time limit T1, the process proceeds from step # 2 to step # 3, and the pulse current superposition signal output is set to the L level. If the pulse superimposed signal is H level in step # 1, the process proceeds to step # 4 to generate a pulse. In step # 4, the pulse current superimposed signal output is set to H level.

  FIG. 6 is a waveform diagram for explaining the operation of this embodiment. As shown in the figure, when the pulse superimposition signal is turned ON, the pulse current is superimposed on the lamp current during that period. When the pulse superposition signal is turned off, the superposition of the pulse current on the lamp current is stopped. If the period during which the pulse superimposed signal is OFF exceeds a predetermined OFF limit time T1, a normal pulse superimposed signal is not input, so that some suitable processing (for example, warning display) is performed at that time, or ,do nothing.

  In the second embodiment, in order to realize the means for counting the elapsed time after the completion of the pulse superposition in the microcomputer 3, for example, when the pulse current superposition signal output changes from the H level to the L level, For example, the count value of the elapsed time after the completion of the pulse superposition is reset, and the count value is incremented every time step # 3 in FIG. 5 is executed.

(Example 3)
FIG. 7 is a flowchart showing the operation of the third embodiment of the present invention, and shows a program for discriminating pulse superposition in the microcomputer 3 of FIG. In this embodiment, as shown in FIG. 8, when the pulse superimposed signal exceeds the ON limit time t1, or when the pulse limit exceeds the OFF limit time T1, what kind of signal the pulse superimposed signal is during the predetermined time t2. Even if it exists, it is characterized by not generating a pulse current.

  The microcomputer 3 periodically executes the flow of FIG. 7 by timer interruption. In step # 11, it is determined whether a timer for counting a predetermined time t2 is operating. In a normal state, this timer is not operating, so the process proceeds to step # 12 to determine whether the pulse superimposed signal input is at the H level or the L level. If the pulse superimposition signal input is at the H level, the process proceeds to step # 13 to determine whether the elapsed time from the start of the pulse superposition exceeds the ON limit time t1. If the ON limit time t1 has not been exceeded, the process proceeds to step # 14 where the pulse current superimposed signal output is set to H level and the interrupt is terminated. If the pulse superimposition signal input is L level in step # 12, the process proceeds to step # 15 to determine whether the elapsed time from the end of the pulse superimposition exceeds the OFF limit time T1. If the OFF limit time T1 has not been exceeded, the process proceeds to step # 16 where the pulse current superimposed signal output is set to the L level and the interrupt is terminated.

  When it is determined in step # 13 that the elapsed time since the start of pulse superposition has exceeded the ON limit time t1, or the elapsed time after the completion of pulse superposition in step # 15 is the OFF limit time T1. If it is determined that the value exceeds the value, the process proceeds to step # 17 to start a timer (a timer built in the microcomputer or a counter created by a program) that counts a predetermined time t2, and then proceeds to step # 16. Then, the pulse current superimposed signal output is set to the L level, and the interruption is completed.

  When the process for determining the state of the pulse superimposed signal is entered again, it is determined in step # 11 that the timer is operating. Therefore, the process proceeds to step # 18 to determine whether or not a predetermined time t2 has elapsed. To do. If the predetermined time t2 has not elapsed, the process proceeds to step # 16, the pulse current superimposed signal output is set to the L level, and the interrupt is terminated. In step # 18, if the predetermined time t2 has elapsed, the process proceeds to step # 19, where the timer for counting the predetermined time t2 is stopped and initialized, and the process proceeds to step # 12. The state of the pulse superimposed signal is determined, and a pulse current superimposed signal is output according to the pulse superimposed signal.

  Thereby, the operation as shown in FIG. 8 is realized. That is, when the time when the pulse superimposed signal is at the H level exceeds the time limit t1, or when the time when the pulse superimposed signal is at the L level exceeds the time limit T1, a normal pulse superimposed signal is not input. Therefore, the superposition of the pulse current is stopped for the predetermined time t2, and after the predetermined time t2 has elapsed, the operation returns to the operation of controlling the pulse current superposition signal output to H / L according to the H / L of the pulse superposition signal. . Thereby, the electric power supplied to the discharge lamp 1 is limited, and electrode wear and damage of the discharge lamp 1 or a failure of the high-pressure discharge lamp lighting device 4 itself can be prevented. In this case, since the supply power to the discharge lamp 1 is insufficient during the predetermined time t2, the shortage of the supply power to the discharge lamp 1 is compensated as in Examples 4 and 5 described later. It is good to add control.

(Example 4)
FIG. 9 is a flowchart showing the operation of the fourth embodiment of the present invention, and shows a program for discriminating pulse superposition in the microcomputer 3 of FIG. In this embodiment, as shown in FIG. 10, when the pulse superimposition signal exceeds the ON limit time t1 or the OFF limit time T1, the pulse current does not matter what the signal is during the predetermined time t2. Is generated periodically. In other words, when the time when the pulse superimposed signal is at the H level exceeds the ON limit time t1, or when the time when the pulse superimposed signal is at the L level exceeds the OFF limit time T1, a normal pulse superimposed signal is not input. Since this is a state, a timer (a timer mounted in the microcomputer or a counter created by a program) that starts measuring a predetermined time t2 is started, and the pulse current superimposed signal output is periodically switched between H level and L level. The port (output terminal A described above) is set (step # 20). If the predetermined time t2 has elapsed when the process for determining the state of the pulse superimposed signal is started again, the timer is stopped and initialized, and the pulse current superimposed signal periodically changes to the H level / L level. The setting to output is canceled (step # 21), the state of the pulse superimposed signal is determined, and the pulse current superimposed signal is output. If the predetermined time t2 has not elapsed in step # 18, the setting is made such that the pulse current superimposed signal output is periodically switched between the H level and the L level. Other operations are the same as those in the flowchart of FIG.

(Example 5)
FIG. 11 is a flowchart showing the operation of the fifth embodiment of the present invention, and shows a program for discriminating pulse superposition in the microcomputer 3 of FIG. In this embodiment, as shown in FIG. 12, when the pulse superimposed signal exceeds the ON limit time t1 or the OFF limit time T1, the lamp current is not limited to any signal during the predetermined time t2. It is characterized by increasing. In other words, when the time when the pulse superimposed signal is at the H level exceeds the ON limit time t1, or when the time when the pulse superimposed signal is at the L level exceeds the OFF limit time T1, a normal pulse superimposed signal is not input. Since it is in a state, a power command is issued to start a timer (a timer mounted in the microcomputer or a counter created by a program) that measures a predetermined time t2 and increase the power control voltage Vref to increase the lamp current. The value output is set (setting to increase the duty of the output terminal B described above) (step # 30). If the predetermined time t2 has elapsed when the process of determining the state of the pulse superimposed signal is started again, the power control voltage is used to stop and initialize the timer and restore the lamp current value. The setting of the power command value output that increases Vref is canceled (step # 31), the state of the pulse superimposed signal is determined, and the pulse current superimposed signal is output. If the predetermined time t2 has not elapsed in step # 18, the power command value output setting for increasing the power control voltage Vref is left as it is. Other operations are the same as those in the flowchart of FIG.

(Example 6)
In the sixth embodiment of the present invention, when the pulse superimposed signal is normally input, the power generated by periodically generating the pulse current in the fourth embodiment or the power generated by increasing the lamp current in the fifth embodiment. It is set so that electric power equivalent to can be supplied to the discharge lamp. In order to realize this, in the processing of the periodic pulse current generation setting (step # 20) in the flow of FIG. 9 and the lamp current increase setting (step # 30) in the flow of FIG. Each setting may be made so that the power is equivalent to the power when a signal is input.

(Example 7)
FIG. 13 is a flowchart showing the operation of the seventh embodiment of the present invention, and shows a program for determining a pulse selection signal in the microcomputer 3 of FIG. In this embodiment, as shown in FIG. 14, for example, when the pulse selection signal selects “synchronous”, the pulse current is superimposed on the lamp current in synchronization with the pulse superimposed signal, and “periodic” is selected. If selected, a pulse current is periodically superimposed on the lamp current. That is, when the pulse selection signal is at the L level, the pulse current superimposed signal IlaUP is output in synchronization with the pulse superimposed signal, and when the pulse selection signal is at the H level, the pulse current superimposed signal is periodically generated regardless of the pulse superimposed signal. Set to output IlaUP.

(Example 8)
FIG. 15 is a circuit diagram of Embodiment 8 of the present invention. In this embodiment, as shown in FIG. 16, the pulse superimposed signal and the lamp lighting signal output from the set side are made into one signal, and the pulse current is changed to the lamp current in synchronization with the pulse superimposed signal depending on the type of the signal. Whether to superimpose or periodically superimpose the pulse current on the lamp current is selected, and the pulse current is superimposed on the lamp current. In FIG. 16, (a) is a case where a synchronized pulse current is generated, and the lamp lighting signal / pulse superimposed signal supplied from the set side of the projector is converted into a rectangular wave signal of H level / L level, thereby increasing the voltage. On the discharge lamp lighting device side, the lamp current operates so as to superimpose a pulse current synchronized with the pulse superposition signal. (B) shows a case in which a periodic pulse current is generated. The lamp lighting signal and pulse superimposed signal supplied from the set side of the projector is set to a constant signal of H level, so that the high pressure discharge lamp lighting device On the side, it operates to superimpose a periodic pulse current on the lamp current. When the lamp lighting signal and pulse superimposed signal supplied from the set side of the projector is a constant signal of L level, it is determined that the lamp is OFF, and the lamp current is 0A.

  In order to realize the above operation, the interface of the high pressure discharge lamp lighting device that receives the signal from the set side of the projector is configured as shown in FIG. 15, and the lamp lighting signal and pulse superimposed signal sent from the set side are The lamp lighting signal, the pulse current selection signal, and the pulse superimposed signal are separated, and the separated signals are input to the terminals b, c, and d of the microcomputer 3 through the discrimination circuit to discriminate each signal.

  The lamp lighting signal / pulse superimposed signal sent from the set side is first insulated by a photocoupler, and the signal is constituted by a diode D101, resistors R104 and R105, and a capacitor C101. Is input to the binary input terminal b of the microcomputer 3 and is less than the threshold voltage Vth for determining the H level / L level of this input port, that is, if it is L level, the lamp is ON, the threshold voltage Vth is exceeded, that is, H level If there is, it is determined that the lamp is OFF.

  Further, the same signal received by the photocoupler is inputted to the binary input terminal c of the microcomputer 3 through a time constant circuit for pulse selection discrimination constituted by the diode D102, the resistors R106 and R107, and the capacitor C102. If the voltage is less than the threshold voltage Vth for determining the H level / L level of the port, that is, the L level, the pulse current superimposed signal IlaUP is periodically output regardless of the pulse superimposed signal. For example, it is determined that the pulse current superimposed signal IlaUP is output in synchronization with the pulse superimposed signal.

  Further, the same signal received by the photocoupler is input to the binary input terminal d of the microcomputer 3 via the resistor R108 and is directly used as a pulse superimposed signal input. The time constants of the capacitor C103 and the resistor R108 are small time constants for removing noise, and the time constants of the capacitor C101 and the resistors R104 and R105 and the capacitor C102 and the resistors R106 and R107 are such that the pulse superimposed signal does not pass through the input port. A large time constant is set.

  As a result, each signal can be discriminated. As shown in FIG. 17, when it is desired to perform periodic pulse current superposition, the lamp lighting signal and pulse superposition signal may be made constant at the H level, When it is desired to superimpose the pulse current in synchronization with the pulse superimposition signal, the lamp lighting signal / pulse superimposition signal may be a rectangular wave signal having a desired H level / L level.

  However, when a pulse superimposed signal is input, the time required for each determination circuit is such that the voltage input to the lamp lighting signal determination port b and the pulse selection determination port c determined by the frequency and ON duty becomes a desired voltage. It is necessary to design constants R104, R105, C101, R106, R107, and C102.

  Further, in this interface circuit, when a pulse superimposed signal composed of an H level / L level rectangular wave signal is input (when a pulse superimposed current is output in synchronization with the pulse superimposed signal), as shown in FIG. When an unstable signal is input, there is a problem that a periodic pulse is generated depending on the constant design of each discrimination circuit and the time when the signal is at the H level, but there is a limit on the time for superimposing the pulse current. Therefore, this problem can be solved.

  In the circuit configuration of FIG. 15 using this interface circuit, any one of the first to sixth embodiments described above may be employed as a microcomputer control program.

Example 9
Any of the high-pressure discharge lamp lighting devices 4 of Examples 1 to 8 can be used as a light source of a projector using the rotating color filter 6 and the fine movable mirror integrated element 8 shown in FIG. In this case, a pulse superposition signal for superimposing the pulse current on the lamp current is supplied from the control circuit 10 on the set side to the high-pressure discharge lamp lighting device 4 at the white (W) timing of the color filter 6 as shown in FIG. Will be. When the monitor signal connector is inserted or removed, even if the pulse superimposed signal may become unstable as shown in FIG. 21, the power supplied to the discharge lamp is limited, and the electrode of the discharge lamp is worn or damaged. Or the failure of the high pressure discharge lamp lighting device 4 can be prevented, and a highly reliable projector can be provided.

It is a circuit diagram of Example 1 of the present invention. It is operation | movement explanatory drawing of Example 1 of this invention. It is a flowchart for operation | movement description of Example 1 of this invention. It is a wave form diagram for operation | movement description of Example 1 of this invention. It is a flowchart for operation | movement description of Example 2 of this invention. It is a wave form diagram for description of operation | movement of Example 2 of this invention. It is a flowchart for operation | movement description of Example 3 of this invention. It is a wave form diagram for description of operation | movement of Example 3 of this invention. It is a flowchart for operation | movement description of Example 4 of this invention. It is a wave form diagram for description of operation | movement of Example 4 of this invention. It is a flowchart for operation | movement description of Example 5 of this invention. It is a wave form diagram for description of operation | movement of Example 5 of this invention. It is a flowchart for operation | movement description of Example 7 of this invention. It is a wave form diagram for operation | movement description of Example 7 of this invention. It is a circuit diagram of Example 8 of the present invention. It is a wave form diagram for operation | movement description of Example 8 of this invention. It is operation | movement explanatory drawing of Example 8 of this invention. It is a schematic block diagram of the conventional image display apparatus. It is a wave form diagram for operation | movement description of the trigger system of a prior art example. It is a wave form diagram for operation | movement description of the synchronous system of a prior art example. It is a wave form diagram for demonstrating the subject of a prior art example.

Explanation of symbols

1 discharge lamp 2 PWM control circuit 3 microcomputer

Claims (10)

A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp by supplying a direct current lamp current, and when the pulse superimposed signal is in the first state, the lamp current is increased compared to that in the second state, In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal, when the time when the pulse superimposition signal is in the first state exceeds the time limit, it is synchronized with the pulse superimposition signal for a predetermined time. A high pressure discharge lamp lighting device characterized by not superimposing a pulse current . A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp by supplying a direct current lamp current, and when the pulse superimposed signal is in the first state, the lamp current is increased compared to that in the second state, In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal, when the time when the pulse superimposition signal is in the first state exceeds the time limit, it is synchronized with the pulse superimposition signal for a predetermined time. Then, instead of superimposing the pulse current, the high-pressure discharge lamp lighting device is characterized by periodically superimposing the pulse current on the lamp current for the predetermined time. A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp by supplying a direct current lamp current, and when the pulse superimposed signal is in the first state, the lamp current is increased compared to that in the second state, In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal, when the time when the pulse superimposition signal is in the first state exceeds the time limit, it is synchronized with the pulse superimposition signal for a predetermined time. Then, the lamp current is increased at the predetermined time without superimposing the pulse current, and the high pressure discharge lamp lighting device. A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp by supplying a direct current lamp current, and when the pulse superimposed signal is in the first state, the lamp current is increased compared to that in the second state, In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal, when the time when the pulse superimposition signal is in the second state exceeds the time limit, it is synchronized with the pulse superimposition signal for a predetermined time. Then, instead of superimposing the pulse current, the high-pressure discharge lamp lighting device is characterized by periodically superimposing the pulse current on the lamp current for the predetermined time. A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp by supplying a direct current lamp current, and when the pulse superimposed signal is in the first state, the lamp current is increased compared to that in the second state, In the high pressure discharge lamp lighting device that superimposes the pulse current on the lamp current in synchronization with the pulse superimposition signal, when the time when the pulse superimposition signal is in the second state exceeds the time limit, it is synchronized with the pulse superimposition signal for a predetermined time. Then, the lamp current is increased at the predetermined time without superimposing the pulse current, and the high pressure discharge lamp lighting device. The ratio of the time of the first state and the time of the second state is determined in advance for the normal pulse superimposed signal according to claim 2 or 4, and the predetermined time when the pulse superimposed signal is not normal is: A high pressure discharge lamp lighting device characterized in that a pulse current is periodically superimposed on a lamp current so that the power is equivalent to that when a normal pulse superimposed signal is input. The ratio of the time of the first state and the time of the second state is determined in advance in the normal pulse superimposed signal according to any one of claims 3 and 5, and the predetermined time when the pulse superimposed signal is not normal is: The lamp current is increased at the predetermined time without superimposing the pulse current in synchronization with the pulse superimposed signal, so that the power is equivalent to the power at the time of normal pulse superimposed signal input. High pressure discharge lamp lighting device. 8. The lamp current according to claim 2, wherein a predetermined signal is used to select whether to superimpose a pulse current in synchronism with a pulse superimposition signal or to periodically superimpose a pulse current to a lamp current. A high pressure discharge lamp lighting device characterized by superimposing current. 9. The high pressure discharge lamp lighting device according to claim 8, wherein the pulse superimposed signal and the lamp lighting signal are used together. An image display device using the high-pressure discharge lamp lighting device according to claim 1 as a light source.

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