JP4438264B2 - Discharge lamp lighting control circuit, method, and discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a discharge lamp lighting control circuit, a method, and a discharge lamp lighting device that perform lighting control of a discharge lamp.
[0002]
[Prior art]
  Conventionally, there is a discharge lamp lighting device as shown in FIG. 9 that generates a high voltage by boosting from a DC power source such as a discharge lamp lighting power source used for an automotive headlamp.
[0003]
  FIG. 9 is a diagram showing an overall configuration of a conventional discharge lamp lighting device, and FIG. 10 is a diagram showing a PWM output signal P generated from a control reference voltage V and a triangular wave S by a conventional discharge lamp lighting control circuit. is there.
[0004]
  A discharge lamp lighting device 110 shown in FIG. 9 includes a power supply circuit unit 120 and a discharge lamp lighting control circuit unit 130. The power supply circuit unit 120 is, for example, a step-down chopper circuit, and is turned on and off at high speed and frequently by a PWM (Pulse Width Modulation) output signal P output from the DC power supply 121, the load 122, and the discharge lamp lighting control circuit unit 130. It comprises a switching element Q that performs repeated switching operations, a choke coil L for smoothing current, a diode D, and a capacitor C. The load 122 includes a discharge lamp 1221 and a detection unit (not shown) that detects a discharge lamp voltage and a discharge lamp current.
[0005]
  The load 122 has an on time t during which the switching element Q is on._onThe power supply voltage is applied only (FIG. 10), and the load current gradually increases at start-up. The load current flows through the diode D as the energy stored in the choke coil L is released, and gradually decreases. Off time t when switching element Q is off_offIn FIG. 10, the voltage applied to the load is zero. When all the energy stored in the choke coil L is released, the load current becomes zero.
[0006]
  The discharge lamp lighting control circuit unit 130 mainly includes an error amplifier 131, a triangular wave oscillation unit 132, a level comparison unit 133, and the like. The error amplifier 131 compares the measured value of the discharge lamp voltage and discharge lamp current detected by the detection unit of the load 122 with a control command value that is a control target value, and amplifies the error to obtain the control reference voltage V. This is output to the level comparison unit 133.
[0007]
  The triangular wave oscillator 132 generates a triangular wave S that is a periodic signal by charging and discharging a capacitor (not shown). The level comparison unit 133 generates a PWM output signal P as shown in FIG. 10 by performing a level comparison between the triangular wave S from the triangular wave oscillation unit 132 and the control reference voltage V from the error amplifier 131, and the power supply circuit unit It outputs to 120 switching elements Q, and performs duty control.
[0008]
[Problems to be solved by the invention]
  The load characteristics of the discharge lamp 1221 generally vary depending on the operating state, and control according to the characteristics is required. In other words, in order to start up early in the operating state when starting the discharge lamp, control capable of responding to steep current and voltage changes is required, and stable operation is possible in the normal operating state after sufficient time has passed since starting. Control of current and voltage is required.
[0009]
  In the conventional discharge lamp lighting control circuit unit 130 in response to such a load characteristic request, the error amplifier 131 is set to an intermediate response characteristic so as to be able to cope with each operation state. Depending on the situation, it may be difficult to deal with, and the rise characteristic may be delayed or the stability may be insufficient. Further, when the discharge lamp lighting control circuit unit 130 is configured by a microcomputer, there is a problem that the response speed is slower than that of an analog circuit.
[0010]
  The present invention has been made to solve the above-described problem, and obtains a high response speed by changing the PWM output by expanding and contracting the periodic signal in the aging direction according to the operating state of the discharge lamp. Accordingly, an object of the present invention is to provide a discharge lamp lighting control circuit, a method, and a discharge lamp lighting device that always realize appropriate lighting control regardless of the operating state of a load.
[0011]
[Means for Solving the Problems]
  According to the first aspect of the present invention, in the discharge lamp lighting control circuit for controlling the lighting of the discharge lamp, the control reference voltage is calculated based on the actually measured value and the control command value obtained periodically corresponding to the operating state of the discharge lamp. A periodic reference signal generating means for generating a periodic signal having a control reference voltage generating means for generating, a first waveform portion whose level increases in the time direction and a second waveform portion whose level decreases in the time direction; During the period of one waveform portion of the second waveform portion, a binary signal obtained by comparing the levels of the control reference voltage and the periodic signal is duty controlled for a chopper that outputs power supplied to the discharge lamp. Output control signal generating means for generating and outputting the output control signal, detection means for detecting the operating state of the discharge lamp as the level of the electric signal, and in a direction to suppress a change in the level of the detected electric signal. 1, 2nd waveform Control means for extending and retracting the other corrugations over time direction andSetting means for setting an upper limit value and a lower limit value of the control reference voltage;WithThe control means is operated when the control reference voltage reaches a set upper limit value and lower limit value.It is characterized by that.
[0012]
  According to this configuration, the control reference voltage is generated based on the actually measured value and the control command value that are periodically obtained corresponding to the operating state of the discharge lamp. On the other hand, a periodic signal having a first waveform portion whose level increases in the temporal direction and a second waveform portion whose level decreases in the temporal direction is generated, and the period of one waveform portion of the first and second waveform portions During this, the levels of the control reference voltage and the periodic signal are compared to obtain a binary signal. This binary signal is generated and output as an output control signal for duty-controlling a chopper that outputs power supplied to the discharge lamp. Then, the operating state of the discharge lamp is detected as the level of the electric signal, and the other waveform portion of the first and second waveform portions is expanded and contracted in the direction of time in a direction that suppresses the change in the level of the detected electric signal. That is, according to the change in the level of the electrical signal indicating the operating state of the discharge lamp, the level of the periodic signal expands or contracts in the time direction of one of the first and second waveform sections, so that the output control signal Since the duty is changed and the responsiveness is improved, the lighting control of the discharge lamp is always appropriate.
[0013]
In addition, the control reference voltage is limited to an upper limit value and a lower limit value, and when the control reference voltage level reaches the upper limit value, the control means is operated so as to lower the on-duty of the chopper, and the control reference voltage level is set to the lower limit value. When the control means is operated so as to increase the on-duty of the chopper when the value is reached, it becomes possible to set the minimum and maximum values of the on-time without limiting the duty control. Lighting control is always appropriate.
[0014]
  According to a second aspect of the present invention, the output control signal generation means includes a level comparison unit that compares levels of the control reference voltage and the periodic signal, and a binary signal output from the level comparison unit. It comprises an output control signal generator for generating the output control signal by outputting only the period of one of the first and second waveform sections. According to this configuration, the level comparison unit compares the levels of the control reference voltage and the periodic signal, and the binary signal output from the level comparison unit is a period of one waveform portion of the first and second waveform portions. As a result, an output control signal is generated. For this reason, it is possible to change the duty ratio between the on time and the off time when the other waveform portion of the first and second waveform portions is expanded and contracted in the aging direction.
[0015]
  The invention according to claim 3 is characterized in that the periodic signal is a triangular wave, and the other waveform portion is a second waveform portion whose level decreases in the temporal direction of the triangular wave. According to this configuration, since the change in the level of the detected electric signal is suppressed by expanding and contracting in the time direction the second waveform portion whose level decreases in the time direction of the triangular wave that is the periodic signal, it is always appropriate. It is possible to control the lighting of the discharge lamp.
[0016]
  The invention according to claim 4 is characterized in that the detecting means detects a level of a discharge lamp current. According to this configuration, the control means can be controlled in accordance with the amount of change in the discharge lamp current.
[0017]
  The invention according to claim 5 is characterized in that the detecting means detects a level of the discharge lamp voltage. According to this configuration, the control means can be controlled in accordance with the amount of change in the discharge lamp voltage.
[0018]
  Claim6The invention described in (1) is characterized by comprising time measuring means for measuring the time from the lighting to turning off of the discharge lamp and the time from turning off to lighting, and operating the control means on the basis of the measured value at the time of lighting. . According to this configuration, the time from the lighting of the discharge lamp to the extinguishing and the time from the extinguishing to the lighting of the lamp are measured by the time measuring means, and the control means is operated based on the measured value at the time of lighting of the discharge lamp. In other words, the discharge lamp is in an unstable state immediately after lighting, and becomes stable after a sufficient amount of time has elapsed, so by measuring the time from the lighting of the discharge lamp to turning it off and the time from turning it off to turning it on, It becomes possible to operate the control means in accordance with the operating state, and the lighting control of the discharge lamp is always appropriate.
[0019]
  Claim7The invention described in (1) is characterized by comprising temperature detection means for detecting the temperature of the discharge lamp, and operating the control means in accordance with the detected temperature. According to this configuration, the temperature of the discharge lamp is detected, and the periodic signal is expanded or contracted in the time direction according to the detected temperature. In other words, the temperature of the discharge lamp rises with the passage of time since lighting, and the temperature falls with the passage of time after turning off, so that the operating state can be determined by detecting the temperature. The lighting control of the corresponding discharge lamp can be performed.
[0020]
  Claim8In the discharge lamp lighting control circuit for controlling the lighting of the discharge lamp, the discharge lamp lighting control circuit is based on the actually measured value and the control command value obtained periodically corresponding to the operating state of the discharge lamp. A control reference voltage generation step for generating a control reference voltage; a periodic signal generation step for generating a periodic signal having a first waveform portion whose level increases in the time direction and a second waveform portion whose level decreases in the time direction; During the period of one of the first and second waveform sections, a binary signal obtained by comparing the levels of the control reference voltage and the periodic signal is output as power supplied to the discharge lamp. An output control signal generation step for generating and outputting an output control signal for duty-controlling the chopper, a detection step for detecting the operating state of the discharge lamp as an electric signal level, and a change in the level of the detected electric signal First, a control step for stretching the other waveform portion of the second waveform portion with time direction direction to suppressA setting step for setting an upper limit value and a lower limit value of the control reference voltage;WithWhen the control reference voltage reaches the set upper limit value and lower limit value, the operation in the control step is performed.It is characterized by that.
[0021]
  According to this configuration, the control reference voltage is generated based on the actually measured value and the control command value that are periodically obtained corresponding to the operating state of the discharge lamp. On the other hand, a periodic signal having a first waveform portion whose level increases in the temporal direction and a second waveform portion whose level decreases in the temporal direction is generated, and the period of one waveform portion of the first and second waveform portions During this, the levels of the control reference voltage and the periodic signal are compared to obtain a binary signal. This binary signal is generated and output as an output control signal for duty-controlling a chopper that outputs power supplied to the discharge lamp. Then, the operating state of the discharge lamp is detected as the level of the electric signal, and the other waveform portion of the first and second waveform portions is expanded and contracted in the direction of time in a direction that suppresses the change in the level of the detected electric signal. That is, according to the change in the level of the electrical signal indicating the operating state of the discharge lamp, the level of the periodic signal expands or contracts in the time direction of one of the first and second waveform sections, so that the output control signal Since the duty is changed and the responsiveness is improved, the lighting control of the discharge lamp is always appropriate.
[0022]
In addition, the control reference voltage is limited to an upper limit value and a lower limit value.When the control reference voltage level reaches the upper limit value, the chopper's on-duty is lowered, and when the control reference voltage level reaches the lower limit value, the chopper By increasing the on-duty, it becomes possible to set the minimum value and maximum value of the on-time without limiting the duty control, and the lighting control of the discharge lamp is always appropriate.
[0023]
  Claim9The invention described in claim 17A discharge lamp lighting device comprising the discharge lamp lighting control circuit according to any one of the above and a chopper. According to this configuration, claims 1 to7Since the discharge lamp lighting control circuit according to any one of the above can control output to the chopper, appropriate lighting control of the discharge lamp is always possible.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 1 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a first embodiment of the present invention. Since the discharge lamp lighting device 1a of the first embodiment basically has the same circuit configuration as that of the conventional example of FIG. 9, the following description will be focused on different parts.
[0025]
  A discharge lamp lighting device 1 a according to the first embodiment includes a power supply circuit unit 2 and a discharge lamp lighting control circuit unit 3.
[0026]
  The power supply circuit unit 2 includes a step-down chopper circuit and a load 22. The step-down chopper circuit is turned on / off by a PWM output signal P which is an output control signal output from the DC power supply 21 and the discharge lamp lighting control circuit unit 3. The switching element Q, the diode D, the choke coil L, and the capacitor C are configured to control the above. The load 22 includes a discharge lamp 221, a detection unit 222 that detects a discharge lamp voltage and a discharge lamp current, and the like.
[0027]
  The discharge lamp lighting control circuit unit 3 includes a calculation unit 4 that outputs a control reference voltage V, a first waveform unit Sa in which the level increases in the time direction as shown in FIG. A triangular wave oscillating unit 32 that generates a triangular wave S that is a periodic signal having a waveform unit Sb, a level comparison unit 33 that compares the level of the control reference voltage V and the triangular wave S, and a PWM output signal that generates a PWM output signal P And a generation unit 34.
[0028]
  The calculation unit 4 functionally includes a current change amount detection unit 41, a control reference voltage generation unit 42, and a triangular wave control unit 43. The arithmetic unit 4 is configured by a microcomputer or the like, and includes a storage unit that temporarily stores processing data such as a RAM or a storage unit that stores a control program for operating each functional unit such as a ROM as necessary.
[0029]
  The current change amount detection unit 41 detects a change amount with respect to time of the current value of the discharge lamp 221 detected by the detection unit 222.
[0030]
  The control reference voltage generation unit 42 generates a control reference voltage V to be output to the level comparison unit 33 and outputs the control reference voltage V to the level comparison unit 33. Specifically, the control reference voltage V is a value obtained by integrating a value obtained by subtracting the target value from the actual measured value of the discharge lamp voltage periodically detected by the detection unit 222.
[0031]
  When the amount of change in the current value detected by the current change amount detection unit 41 increases, the triangular wave control unit 43 extends the second waveform portion Sb of the triangular wave S in a timewise direction so that the change amount decreases. In this case, the triangular wave oscillating unit 32 is controlled so as to shorten the second waveform portion Sb of the triangular wave S in the direction of time so as to correspond.
[0032]
  The triangular wave oscillating unit 32 generates a periodic triangular wave S by charge / discharge control of a capacitor (not shown), and a signal indicating the period of the first waveform unit Sa in which the level of the triangular wave S increases in the time direction. A first waveform period output unit 321 for outputting is included. That is, the first waveform section period output unit 321 outputs a high level signal to the PWM output signal generation section 34 during the output period of the first waveform section Sa.
[0033]
  The level comparison unit 33 compares the level of the control reference voltage V output from the control reference voltage generation unit 42 with the triangular wave S that is a periodic signal output from the triangular wave oscillating unit 32, and the triangular wave S has a higher level. During this period, a high level signal as a binary signal is output (see signal P ′ indicated by a broken line in FIG. 2A).
[0034]
  The PWM output signal generation unit 34 is composed of, for example, an AND circuit, and takes a logical product of the output signal P ′ output from the level comparison unit 33 and the high level signal output from the first waveform unit period output unit 321. Thus, the step-down chopper circuit that outputs the power supplied to the discharge lamp 221 is generated and output as a PWM output signal P for duty control. As a result, a PWM output signal P as shown by the solid line in FIG. 2A is obtained.
[0035]
  In the first embodiment, the control reference voltage generation unit 42 corresponds to the control reference voltage generation unit, the triangular wave oscillation unit 32 corresponds to the periodic signal generation unit, the level comparison unit 33 and the PWM output signal generation unit. 34 corresponds to an output control signal generation unit, the detection unit 222 and the current change amount detection unit 41 correspond to a detection unit, and the triangular wave control unit 43 corresponds to a control unit.
[0036]
  Next, the operation of the discharge lamp lighting control circuit in the first embodiment will be described. First, the control reference voltage generation unit 42 integrates a value obtained by subtracting a control command value, which is a target value, from an actual measurement value of a voltage applied to the discharge lamp 221 obtained periodically, and a control reference such that the value becomes zero. The voltage V is output to the level comparison unit 33. When the change amount of the current value detected by the current change amount detection unit 41 increases, the triangular wave control unit 43 converts the waveform portion of the triangular wave S shown in FIG. 2A to a triangular wave as shown in FIG. The triangular wave oscillating unit 32 is controlled so as to extend the second waveform portion Sb of S in the temporal direction by changing the gradient. The triangular wave control unit 43 controls the triangular wave oscillating unit 32 so that the second waveform portion Sb of the triangular wave S is shortened in the time direction when the amount of change in the current value detected by the current change amount detecting unit 41 decreases. To do. The triangular wave oscillating unit 32 outputs the triangular wave signal controlled by the triangular wave control unit 43 to the level comparison unit 33.
[0037]
  Further, the first waveform section period output section 321 outputs an output signal indicating the high level and the output period of the first waveform section Sa of the triangular wave S to the PWM output signal generation section 34. The level comparison unit 33 performs level comparison between the control reference voltage V and the triangular wave S, and outputs a high-level output signal to the PWM output signal generation unit 34 while the level of the triangular wave S is high. The PWM output signal generation unit 34 obtains a logical product of the output signal P ′ from the level comparison unit 33 and the output signal from the first waveform period output unit 321 to obtain the logical product of FIGS. 2 (a) and 2 (b). A PWM output signal P indicated by a solid line is output to the switching element Q. On / off control of the switching element Q is performed by the PWM output signal P, and lighting control of the discharge lamp 221 is performed. When the triangular wave S is larger than the control reference voltage V, the PWM output signal P is controlled to turn on the step-down chopper circuit.
[0038]
  As described above, when the amount of change in the current value increases, the control reference voltage V is constant and the on-time t is extended by extending the second waveform portion Sb of the triangular wave S in the time direction._onOFF time t even when is constant_offTherefore, the on-duty of the PWM output is reduced, and the current average value of the discharge lamp 221 is controlled to be reduced, so that it is possible to cope with a sudden change in current. Further, when the amount of change in the current value decreases, the control reference voltage V is constant and the on time t is shortened by shortening the second waveform portion Sb of the triangular wave S in the time direction._onOFF time t even when is constant_offTherefore, the on-duty of the PWM output is increased, the current average value of the discharge lamp 221 is controlled to be increased, and a sudden current change can be dealt with.
[0039]
  FIG. 3 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to the second embodiment of the present invention. Since the circuit configuration of the discharge lamp lighting device 1b of the second embodiment is basically the same as that of the first embodiment of FIG. 1, the following description will be focused on different parts.
[0040]
  The calculation unit 4 functionally includes a voltage change amount detection unit 44 in addition to the configuration of the first embodiment. In the second embodiment, the voltage change amount detection unit 44 corresponds to a detection unit.
[0041]
  The voltage change amount detection unit 44 detects a change amount with respect to time of the voltage value of the discharge lamp 221 detected by the detection unit 222.
[0042]
  The triangular wave control unit 43 extends the second waveform portion Sb of the triangular wave S in the temporal direction so as to correspond to the case where the change amount of the voltage value detected by the voltage change amount detection unit 44 decreases, and the change amount increases. The triangular wave oscillating unit 32 is controlled so as to shorten the second waveform portion Sb of the triangular wave S in the temporal direction so as to correspond to the case. That is, the second waveform portion Sb of the triangular wave S is expanded or contracted in the direction of time in a direction that suppresses a change in the level of the detected electrical signal.
[0043]
  Next, the operation of the discharge lamp lighting control circuit in the second embodiment will be described. First, the control reference voltage generation unit 42 integrates a value obtained by subtracting a control command value, which is a target value, from an actual measurement value of a voltage applied to the discharge lamp 221 obtained periodically, and a control reference such that the value becomes zero. The voltage V is output to the level comparison unit 33. When the change amount of the voltage value detected by the voltage change amount detection unit 44 is reduced, the triangular wave control unit 43 changes the waveform of the triangular wave S shown in FIG. 2A to that of the triangular wave S as shown in FIG. The triangular wave oscillating unit 32 is controlled so as to extend the second waveform unit Sb in the temporal direction. The triangular wave control unit 43 controls the triangular wave oscillating unit 32 so that the second waveform portion Sb of the triangular wave S is shortened in the time direction when the amount of change in the voltage value detected by the voltage change amount detecting unit 44 increases. To do. The triangular wave oscillating unit 32 outputs the triangular wave signal controlled by the triangular wave control unit 43 to the level comparison unit 33.
[0044]
  Further, the first waveform section period output section 321 outputs an output signal indicating the high level and the output period of the first waveform section Sa of the triangular wave S to the PWM output signal generation section 34. The level comparison unit 33 performs level comparison between the control reference voltage V and the triangular wave S, and outputs a high-level output signal to the PWM output signal generation unit 34 while the level of the triangular wave S is high. The PWM output signal generation unit 34 obtains a logical product of the output signal from the level comparison unit 33 and the output signal from the first waveform unit period output unit 321, thereby obtaining a solid line in FIGS. 2 (a) and 2 (b). The PWM output signal P shown is output to the switching element Q. On / off control of the switching element Q is performed by the PWM output signal P, and lighting control of the discharge lamp 221 is performed. When the triangular wave S is larger than the control reference voltage V, the PWM output signal P is controlled to turn on the step-down chopper circuit.
[0045]
  In this way, when the change amount of the voltage value decreases, the control reference voltage V is constant and the on-time t is extended by extending the second waveform portion Sb of the triangular wave S in the time direction._onOFF time t even when is constant_offTherefore, the on-duty of the PWM output is reduced, and the voltage average value of the discharge lamp 221 is controlled to be increased, so that a sudden voltage change can be dealt with. Further, when the change amount of the voltage value increases, the control reference voltage V is constant and the on-time t is shortened by shortening the second waveform portion Sb of the triangular wave S in the time direction._onOFF time t even when is constant_offTherefore, the on-duty of the PWM output is increased, and the voltage average value of the discharge lamp 221 is controlled to be reduced, so that a sudden voltage change can be dealt with.
[0046]
  FIG. 4 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to the third embodiment of the present invention. Since the circuit configuration of the discharge lamp lighting device 1c of the third embodiment is basically the same as that of the first embodiment of FIG. 1, the following description will be focused on different parts.
[0047]
  The calculation unit 4 functionally includes an upper limit and a lower limit value setting unit 45 in addition to the configuration of the first embodiment. In the third embodiment, the upper and lower limit setting unit 45 corresponds to a setting unit.
[0048]
  The upper limit / lower limit setting unit 45 provides upper limit and lower limit restrictions on the control reference voltage output, and the upper limit value is set lower than the maximum value of the triangular wave S and the lower limit value is set higher than the minimum value of the triangular wave S.
[0049]
  FIG. 5 is a diagram for explaining an upper limit value and a lower limit value of the control reference voltage output V. FIG. Here, when the control reference voltage V is between the upper limit value Va and the lower limit value Vb, the triangular wave control unit 43 controls the triangular wave oscillating unit 32 so that the output waveform of the triangular wave S is constant and outputs the control reference voltage. The PWM output P is duty-controlled only by the magnitude of V (FIG. 5A).
[0050]
  When a low on-duty state is required depending on the load state, the triangular wave control unit 43 changes the second waveform portion Sb of the triangular wave S to the triangular wave oscillating unit 32 at the time when the control reference voltage V reaches the upper limit value Va. The triangular wave S is converted to the triangular wave S₁Output waveform, and PWM output signal P on time t_onTo shorten off time t_offTry to make it longer. This control can reduce the on-duty (FIG. 5B).
[0051]
  When a high on-duty state is required depending on the load state, the triangular wave control unit 43 changes the second waveform unit Sb of the triangular wave S to the triangular wave oscillating unit 32 at the time when the control reference voltage V reaches the lower limit value Vb. By controlling so that the triangular wave S is shortened to₂Output waveform, and PWM output signal P on time t_onIncrease the off time t_offTry to keep it short. This control makes it possible to increase the on-duty (FIG. 5C).
[0052]
  In this way, the control reference voltage V is limited to the upper limit value Va and the lower limit value Vb, and the triangular wave control unit 43 is operated so as to reduce the on-duty of the chopper when the level of the control reference voltage V reaches the upper limit value Va. By operating the triangular wave control unit 43 so as to increase the on-duty of the chopper when the level of the control reference voltage V reaches the lower limit value Vb, the on-time t is set without limiting the duty control._onThe minimum value and the maximum value can be set, and stable lighting control of the discharge lamp 221 can be performed.
[0053]
  In the third embodiment, the upper and lower limit setting units 45 are provided in addition to the configuration of the first embodiment. However, the present invention is not particularly limited thereto, and the configuration of the second embodiment. In addition, an upper and lower limit setting unit 45 may be provided.
[0054]
  FIG. 6 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to the fourth embodiment of the present invention. Since the circuit configuration of the discharge lamp lighting device 1d of the fourth embodiment is basically the same as that of the first embodiment of FIG. 1, the following description will be focused on different parts.
[0055]
  In the fourth embodiment, the discharge lamp lighting control circuit unit 3 includes a timer 5 in addition to the first embodiment. In the fourth embodiment, the timer 5 corresponds to a time measuring means.
[0056]
  The timer 5 measures the time from turning on and off of the discharge lamp 221 and the time from turning off to turning on. When the discharge lamp 221 is off for a sufficiently long time, the value of the timer 5 is 0. When the discharge lamp 221 is lit from this state, the value of the timer 5 is counted up. When the lighting state continues for a sufficiently long time, the timer 5 stops counting up at a preset value. Next, when the discharge lamp 221 is turned off from the lighting state, the value of the timer 5 is counted down, and is counted down until the value of the timer 5 becomes zero. Here, when the discharge lamp 221 is turned on and turned off before the value of the timer 5 reaches a preset value, the countdown starts from the count value of the timer 5 at that time. Similarly, when the discharge lamp 221 is turned off and turned on again before the value of the timer 5 reaches 0, the count value of the timer 5 at that time is counted up.
[0057]
  The discharge lamp 221 immediately after lighting is in a low load state, and control for suppressing power is performed to prevent overcurrent. Therefore, the on duty of the PWM output signal P needs to be low. Therefore, when the count value of the timer 5 is a small value, the off time t_offTry to make it longer. That is, the triangular wave control unit 43 controls the triangular wave oscillating unit 32 so as to extend the second waveform portion Sb of the triangular wave S in the temporal direction.
[0058]
  As described above, when the value of the timer 5 is small, the discharge lamp 221 is in an unstable state shortly after the light is turned on. Therefore, the first waveform portion Sa or the second waveform portion Sb of the triangular wave S is moved in the temporal direction. Off time t by stretching_offAnd the lighting control of the stable discharge lamp 221 is performed. When the value of the timer 5 is large, since the discharge lamp 221 is lit and a sufficient time has passed and is stable, the first waveform portion Sa or the second waveform portion Sb of the triangular wave S is moved in the direction of time. By shortening to an off time t_offAnd the lighting control of the stable discharge lamp 221 is performed.
[0059]
  In the fourth embodiment, the timer 5 is provided in addition to the configuration of the first embodiment. However, the present invention is not particularly limited to this, and the timer 5 is added to the configuration of the second embodiment. You may prepare.
[0060]
  FIG. 7 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to the fifth embodiment of the present invention. Since the circuit configuration of the discharge lamp lighting device 1e of the fifth embodiment is basically the same as that of the first embodiment of FIG. 1, the following description will be focused on different parts.
[0061]
  In the fifth embodiment, the power supply circuit unit 2 includes a temperature detection unit 23 in addition to the configuration of the first embodiment. In the fifth embodiment, the temperature detector 23 corresponds to a temperature detector.
[0062]
  When the discharge lamp 221 is turned on, the temperature rises with the passage of time due to self-heating, and when it is turned off, the discharge lamp 221 is naturally cooled and the temperature is lowered with the passage of time. Therefore, detection similar to the timer 5 in the fourth embodiment is possible by providing the temperature detection unit 23. When the temperature detected by the temperature detector 23 is low, the off time t_offTry to make it longer. That is, the triangular wave control unit 43 controls the triangular wave oscillating unit 32 so as to extend the second waveform portion Sb of the triangular wave S in the temporal direction. Note that the level of the detected temperature is determined at a preset temperature.
[0063]
  Thus, when the temperature of the discharge lamp 221 is low, the discharge lamp 221 is in an unstable state shortly after being turned on, and therefore the first waveform portion Sa or the second waveform portion Sb of the triangular wave S is moved in the time direction. By extending to the off time t_offAnd the lighting control of the stable discharge lamp 221 is performed. In addition, when the temperature of the discharge lamp 221 is high, the discharge lamp 221 is turned on and is in a stable state after a sufficient time has passed, so that the first waveform portion Sa or the second waveform portion Sb of the triangular wave S is changed over time. OFF time t by shortening in the direction_offAnd the lighting control of the stable discharge lamp 221 is performed.
[0064]
  In the fifth embodiment, the temperature detector 23 is provided in addition to the configuration of the first embodiment. However, the present invention is not particularly limited to this, and the temperature is added to the configuration of the second embodiment. You may provide the detection part 23. FIG.
[0065]
  FIG. 8 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to the sixth embodiment of the present invention. Since the circuit configuration of the discharge lamp lighting device 1f of the sixth embodiment is basically the same as that of the first embodiment of FIG. 1, the following description is only for the features of the present embodiment. Do.
[0066]
  In the sixth embodiment, in addition to the first embodiment, the power supply circuit unit 2 includes an instantaneous value detection unit 24, and the discharge lamp lighting control circuit unit 3 includes an instantaneous value comparison unit 35. In the sixth embodiment, the instantaneous value detector 24 corresponds to the instantaneous value detector, and the instantaneous value comparator 35 corresponds to the instantaneous value comparator.
[0067]
  The instantaneous value detector 24 detects the instantaneous value of the discharge lamp current. The instantaneous value comparison unit 35 compares the preset upper limit value of the current instantaneous value with the instantaneous value of the discharge lamp current detected by the instantaneous value detection unit 24. The PWM output signal generation unit 34 calculates the logical product of the output value from the instantaneous value comparison unit 35 and the output value from the level comparison unit 33 and the first waveform unit period output unit 321 to obtain the PWM output signal P and To do.
[0068]
  Normally, by extending or contracting the waveform portion of the triangular wave S in the temporal direction, the pulse width of the PWM output signal P becomes larger or smaller, so that excess current flows. Therefore, one of the first waveform portion Sa and the second waveform portion Sb of the triangular wave S is expanded and contracted in the direction of time, so that an excess current is prevented from flowing through the discharge lamp 221 and is below a predetermined current upper limit value. It becomes possible to control the lighting of the discharge lamp 221 with this current.
[0069]
  In the sixth embodiment, the instantaneous value detection unit 24 and the instantaneous value comparison unit 35 are provided in addition to the configuration of the first embodiment. However, the present invention is not particularly limited thereto, and the second to fifth examples are provided. In addition to the configuration of the embodiment, the instantaneous value detection unit 24 and the instantaneous value comparison unit 35 may be provided.
[0070]
  In the present embodiment, the output period of the first waveform portion Sa of the triangular wave S, the output signal indicating the high level, the control reference voltage V and the triangular wave S are compared in level, and the high level of the triangular wave S is high. The PWM output signal P is obtained by calculating the logical product with the output signal indicating the level. However, the present invention is not particularly limited to this, and the output period of the second waveform portion Sb of the triangular wave S and the output signal indicating the high level The PWM output signal P may be obtained by comparing the control reference voltage V and the triangular wave S with each other and obtaining a logical product with the output signal indicating the high level during a period when the level of the triangular wave S is high. In this case, the triangular wave control unit 43 performs duty control of the chopper by expanding and contracting the first waveform portion Sa of the triangular wave S in the temporal direction.
[0071]
  In the present embodiment, the periodic signal is described as the triangular wave S. However, the present invention is not particularly limited to this, and other periodic signals may be used.
[0072]
  In the present embodiment, the power supply circuit unit 2 has been described as a step-down chopper circuit. However, the present invention is not particularly limited thereto, and may be a step-up chopper circuit or a step-up / step-down chopper circuit.
[0073]
【The invention's effect】
  According to the first aspect of the present invention, in response to a change in the level of the electric signal indicating the operating state of the discharge lamp, the level of the periodic signal is one of the first and second waveform portions in the direction of time. By expanding and contracting, the duty of the output control signal changes and the responsiveness is improved, so that the discharge lamp lighting control is always appropriate.
[0074]
In addition, the control reference voltage is limited to an upper limit value and a lower limit value, and when the control reference voltage level reaches the upper limit value, the control means is operated to lower the on-duty of the chopper, and the control reference voltage level is set to the lower limit value. By operating the control means to increase the on-duty of the chopper when the value is reached, the minimum and maximum on-time can be set without limiting the duty control, and the discharge lamp is turned on Control is always appropriate.
[0075]
  According to the second aspect of the present invention, the duty ratio between the on time and the off time can be changed when the other waveform portion of the first and second waveform portions is expanded and contracted in the aging direction.
[0076]
  According to the third aspect of the present invention, the change in the level of the detected electrical signal is suppressed by expanding and contracting in the time direction the second waveform portion whose level decreases in the time direction of the triangular wave that is the periodic signal. Therefore, the lighting control of the discharge lamp is always appropriate.
[0077]
  According to invention of Claim 4, control of the control means according to the variation | change_quantity of the discharge lamp electric current can be performed.
[0078]
  According to invention of Claim 5, control of the control means according to the variation | change_quantity of the discharge lamp voltage can be performed.
[0079]
  Claim6According to the invention described in the above, the control means can be operated in accordance with the operating state at the time of lighting by measuring the time from lighting to turning off and the time from turning off to lighting. Lighting control is always appropriate.
[0080]
  Claim7According to the invention described in (1), it is possible to determine the operating state by detecting the temperature, and it is possible to control the lighting of the discharge lamp according to the operating state.
[0081]
  Claim8According to the invention described in (1), in accordance with the change in the level of the electrical signal indicating the operating state of the discharge lamp, the level of the periodic signal expands or contracts in the time direction in one of the first and second waveform portions. As a result, the duty of the output control signal changes and the responsiveness is improved, so that the lighting control of the discharge lamp is always appropriate.
[0082]
In addition, the control reference voltage is limited to an upper limit value and a lower limit value.When the control reference voltage level reaches the upper limit value, the chopper's on-duty is lowered, and when the control reference voltage level reaches the lower limit value, the chopper By increasing the on-duty, the minimum value and the maximum value of the on-time can be set without limiting the duty control, and the lighting control of the discharge lamp is always appropriate.
[0083]
  Claim9The discharge lamp lighting control circuit can control the output to the chopper and can always appropriately control the lighting of the discharge lamp.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a waveform of a PWM output signal obtained from a control reference voltage value and a triangular wave output value.
FIG. 3 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a second embodiment of the present invention.
FIG. 4 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a third embodiment of the present invention.
FIG. 5 is a diagram for explaining an upper limit and a lower limit of a control reference voltage.
FIG. 6 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a fourth embodiment of the present invention.
FIG. 7 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a fifth embodiment of the present invention.
FIG. 8 is an overall configuration diagram of a discharge lamp lighting device including a discharge lamp lighting control circuit according to a sixth embodiment of the present invention.
FIG. 9 is a diagram showing an overall configuration of a conventional discharge lamp lighting device.
FIG. 10 is a diagram showing a PWM output signal generated from a control reference voltage and a triangular wave by a conventional discharge lamp lighting control circuit.
[Explanation of symbols]
1a to 1g Discharge lamp lighting device
2 Power supply circuit
3 Discharge lamp lighting control circuit
4 Calculation unit
5 Timer
23 Temperature detector
24 Instantaneous value detector
32 Triangular wave oscillator
33 Level comparison section
34 PWM output signal generator
35 Instantaneous value comparator
41 Current change detection unit
42 Control reference voltage generator
43 Triangular wave control unit
44 Voltage change amount detector
45 Upper / lower limit setting section
221 Discharge lamp
222 Detector
321 First waveform section period output section

Claims (9)

In a discharge lamp lighting control circuit that performs lighting control of the discharge lamp, control reference voltage generation means that generates a control reference voltage based on an actually measured value and a control command value that are periodically obtained corresponding to the operating state of the discharge lamp; Periodic signal generating means for generating a periodic signal having a first waveform portion whose level increases in the time direction and a second waveform portion which decreases in the time direction; and one of the first and second waveform portions During this period, a binary signal obtained by comparing the levels of the control reference voltage and the periodic signal is generated as an output control signal for duty-controlling a chopper that outputs power supplied to the discharge lamp, and output Output control signal generating means for detecting, detecting means for detecting the operating state of the discharge lamp as the level of the electric signal, and the other of the first and second waveform sections in a direction to suppress a change in the level of the detected electric signal. Waveform part over time Control means for expanding and contracting in, and a setting means for setting upper and lower limit values of the control reference voltage, operate to the control unit when the control reference voltage reaches a set upper limit value and the lower limit value A discharge lamp lighting control circuit characterized by that.   The output control signal generation means includes a level comparison unit that compares levels of the control reference voltage and the periodic signal, and a binary signal output from the level comparison unit as one of the first and second waveform units. The discharge lamp lighting control circuit according to claim 1, further comprising: an output control signal generation unit that generates the output control signal by outputting only during the period of the waveform part.   2. The discharge lamp lighting control circuit according to claim 1, wherein the periodic signal is a triangular wave, and the other waveform portion is a second waveform portion whose level decreases in the direction of time of the triangular wave.   The discharge lamp lighting control circuit according to claim 1, wherein the detection unit detects a level of a discharge lamp current.   The discharge lamp lighting control circuit according to claim 1, wherein the detection unit detects a level of the discharge lamp voltage. The time of the time from lighting of a discharge lamp to light extinction and the time from light extinction to lighting are provided, and the said control means is operated based on the measured value at the time of lighting. The discharge lamp lighting control circuit according to any one of the above. The discharge lamp lighting control circuit according to any one of claims 1 to 3, further comprising temperature detection means for detecting a temperature of the discharge lamp, and operating the control means in accordance with the detected temperature. In a discharge lamp lighting control circuit that performs discharge lamp lighting control, the discharge lamp lighting control circuit generates a control reference voltage based on periodically measured values and control command values corresponding to the operating state of the discharge lamp. A control reference voltage generation step; a periodic signal generation step for generating a periodic signal having a first waveform portion whose level increases in the time direction and a second waveform portion whose level decreases in the time direction; During the period of one of the waveform parts, the binary signal obtained by comparing the levels of the control reference voltage and the periodic signal is an output for duty-controlling a chopper that outputs power supplied to the discharge lamp An output control signal generation step for generating and outputting as a control signal, a detection step for detecting the operating state of the discharge lamp as an electric signal level, and a direction for suppressing a change in the level of the detected electric signal 1. A control step for expanding / contracting the other waveform portion of the second waveform portion in the aging direction, and a setting step for setting an upper limit value and a lower limit value of the control reference voltage, and an upper limit value at which the control reference voltage is set And the operation in the said control step is performed when the lower limit is reached, The discharge lamp lighting control method characterized by the above-mentioned. A discharge lamp lighting device comprising the discharge lamp lighting control circuit according to any one of claims 1 to 7 and a chopper.

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