JPH04286897A - Illumination load control device - Google Patents

Abstract

PURPOSE:To modulate light continuously between lower limit and upper limit by setting the fixed upper limit of a light output level, and enabling only the lower limit to be altered step by step. CONSTITUTION:A high frequency conversion circuit 1 is provided for converting an output voltage from a d.c. power supply E1 to a high frequency voltage and applying it to an illumination load 2. By changing on-duty of a continuous modulated light signal continuously, an output voltage V0 of the 1st modulated light control circuit 3 is changed continuously. The lower limit value of the output voltage V0 of the 1st modulated light control circuit 3 is set to 0V and the upper limit value is set step by step by resistors R15 to R17 and switches SW1 and SW2. An output voltage V0 is applied to a mono-stable multivibrator MUL which decides the optical output level of the illumination load 2. The upper limit value of the optical output level of the illumination load 2 become constant, depending on the lower limit value of the output voltage V0, and the lower limit value is set step by step depending on the upper limit value of the output voltage V0.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting load control device for dimming and lighting a lighting load at a high frequency.

0002

2. Description of the Related Art Conventionally, a lighting load control device having a configuration as shown in FIG. 5 has been provided. That is, the DC power source E
1 (which may be a rectified AC power supply) is converted into a high frequency voltage by a high frequency conversion circuit 1, and the obtained high frequency voltage is used to start and light a lighting load 2 such as a discharge lamp. It is. The high frequency conversion circuit 1 controls the output to the lighting load 2 in response to the outputs of the first dimming control circuit 3 and the second dimming control circuit 4, and adjusts the level of light output of the lighting load 2. It looks like this. The first dimming control circuit 3 continuously changes the level of the light output of the lighting load 2 in response to the continuous dimming signal from the first dimming setting section 5, and the second dimming control circuit 4 continuously changes the level of the light output of the lighting load 2. is configured to receive a step dimming signal from the second dimming setting section 6 and change the level of the light output of the lighting load 2 in multiple stages.

FIG. 6 shows a concrete circuit having the configuration shown in FIG. 5, and the high frequency conversion circuit 1 is constituted by a so-called series type inverter circuit. The high frequency conversion circuit 1 includes a series circuit of a pair of transistors Q1 and Q2 as switching elements connected across a DC power source E1, and diodes D1 and D2 are connected between the collector and emitter of each transistor Q1 and Q2, respectively. Connected in antiparallel. Between both ends of one transistor Q1, there is a coupling capacitor C0 for cutting the DC component, a lighting load 2 consisting of a discharge lamp, an inductor L that serves both current limiting and resonance purposes, and a transistor that connects the load current to the lighting load 2. Q1
The primary winding n1 of the current transformer CT for feedback to
series circuit is connected. Further, a capacitor C1 for resonance and a capacitor C2 for resonance and for passing preheating current are connected in parallel between both ends of the lighting load 2. The secondary winding n2 of the current transformer CT is connected in series with the resistor R5, and this series circuit connects the base of the transistor Q1,
Connected between emitters. On the other hand, a series circuit of resistors R1 and R2 is connected between the collector and emitter of transistor Q2. The connection point between both resistors R1 and R2 is connected to the trigger terminal B of the monostable multivibrator MUL, so that the monostable multivibrator MUL is triggered by the fall of the input signal to the trigger terminal B. For the monostable multivibrator MUL, for example, a general-purpose integrated circuit such as μPD4538 manufactured by NEC Corporation can be used. Monostable multivibrator MU
The period during which the output level of the L non-inverting output terminal Q is at the H level (that is, the period during which the output level at the inverting output terminal NQ is at the L level) is basically determined by the resistor R4 and the capacitor C4. The non-inverting output terminal Q is connected to the base of the transistor Q4 via the bias resistor R6, and the inverting output terminal NQ is connected to the base of the transistor Q4 via the bias resistor R6.
7 to the base of transistor Q5. The collectors and emitters of both transistors Q4 and Q5 are connected in series, and this series circuit is connected across the DC power source E2. Further, the connection point between the emitter of the transistor Q4 and the collector of the transistor Q5 is connected to the base of the transistor Q2 via a bias resistor R8. Therefore, the period during which the output level of the non-inverting output terminal Q of the monostable multivibrator MUL is at H level determines the period during which the transistor Q2 is turned on.

Now, when the transistor Q2 is turned on, the connection point between the resistors R1 and R2 goes to the L level, so the monostable multivibrator MUL is triggered and the output level of the non-inverting output terminal Q goes to the H level for a predetermined period. Become,
During this period, transistor Q2 remains on. When transistor Q2 turns on, DC power supply E1
Current flows through the following path: positive electrode → coupling capacitor C0 → lighting load 2 → inductor L → primary winding n1 of current transformer CT → transistor Q2 → negative pole of DC power supply E1. The primary windings n1 and 2 are connected so that a current flows through the wire n2 so that the base and emitter of the transistor Q1 are reverse biased.
Since the polarity with the next winding n2 is set, the transistor Q1 remains off. After that, when the output level of the non-inverting output terminal Q of the monostable multivibrator MUL becomes L level, the transistor Q2 turns off, but since the inductor L tries to flow the current in the same direction,
Diode D1 becomes conductive. In addition, current transformer CT
A reverse induced voltage is generated in the secondary winding n2 of the transistor Q1, and the transistor Q1 is forward biased and turned on. When no current flows through the diode D1, a current flows through the transistor Q1 using the accumulated charge in the coupling capacitor C0 as a power source. When the core of the inductor L reaches saturation magnetic flux due to this current, the collector current of the transistor Q1 rapidly decreases, the base current of the transistor Q1 induced in the secondary winding n2 of the current transformer CT decreases, and the transistor Q1 It turns off. Transistor Q1
Since current continues to flow in the same direction in the inductor L even after the inductor L is turned off, the current flowing through the diode D3 etc. makes the diode D2 conductive, and the resistor R1
, R2 become zero, trigger terminal B of monostable multivibrator MUL is triggered, and transistor Q2 is forward biased. When no current flows through diode D2, current flows through transistor Q2. By repeating the above operations, the high frequency conversion circuit 1 performs an oscillation operation and lights up the lighting load 2 at high frequency.

As mentioned above, to start the high frequency conversion circuit 1, it is sufficient to turn on the transistor Q2, and the starting circuit 7 starts the high frequency conversion circuit 1 by turning on the transistor Q2.
and a series circuit of capacitor C3, and a trigger element Q3 having one end connected to the connection point between resistor R3 and capacitor C3 and the other end connected to the base of transistor Q2.
It is composed of Therefore, when the DC power source E1 is connected, the capacitor C3 is charged via the resistor R3, and the voltage across the capacitor C3 becomes the trigger element Q.
When the breakover voltage of 3 is reached, the transistor Q
A base current flows through the base of the high-frequency conversion circuit 1, and the oscillation operation of the high-frequency conversion circuit 1 can be started.

By the way, in the high frequency conversion circuit 1 having the above configuration, the amount of energy stored in the inductor L is controlled by adjusting the period during which the output level of the non-inverting output terminal Q of the monostable multivibrator MUL is at H level. Then, the level of light output of the lighting load 2 can be adjusted. In order to perform such dimming control, the output voltages of the first dimming control circuit 3 and the second dimming control circuit 4 are
The voltage is applied to the connection point between the resistor R4 and the capacitor C4, and by changing the output voltage of the first dimming control circuit 3 and the second dimming control circuit 4, the charging time of the capacitor C4 is changed, and the non-inverting output terminal The period during which the output level of Q is at H level can be changed.

The first dimming control circuit 3 receives a continuous dimming signal from the first dimming setting section 5 and sets an output voltage, and the continuous dimming signal has a constant frequency. A pulse signal whose on-duty is variable is used. The first dimming control circuit 3 transmits such a continuous dimming signal to a NOT circuit NOT (for example, NEC μPD40
49), and resistor R9 is inverted at the output of the NOT circuit NOT.
After charging capacitor C5 through
5 voltage across operational amplifier OP1 and resistor R10
Input to the differential amplifier consisting of ~R14, capacitor C5
An output proportional to the difference between the voltage across the terminal and the potential at the connection point of the resistors R12 and R13 is obtained. The output of the differential amplifier is applied to the monostable multivibrator MUL via an impedance converter comprising an operational amplifier OP2, a resistor R14, and a diode D4 so that the output has a low impedance. Therefore, the first dimming control circuit 3
As shown in FIG. 7, the output voltage V0 increases as the on-duty of the continuous dimming signal obtained from the first dimming setting section 5 increases. If the potential at the connection point between resistor R4 and capacitor C4 becomes higher, capacitor C
4 becomes shorter, the period during which the output level of the non-inverting output terminal Q of the monostable multivibrator MUL is at H level becomes shorter, and as a result, the level of the optical output of the lighting load 2 becomes smaller. In short, the larger the on-duty of the continuous dimming signal, the smaller the light output level of the lighting load 2 becomes.

On the other hand, the second dimming control circuit 4 changes the output voltage according to the stage dimming signal from the second dimming setting section 6, and the second dimming setting section 6 has a pair of dimming control circuits. switch S
It is composed of W1 and SW2. Each switch SW1
, SW2 are connected in series with resistors R15 and R16,
One end of a parallel circuit in which both series circuits are connected in parallel is connected to the positive electrode of the DC power source E2, and the other end is connected to the connection point between the resistor R4 and the capacitor C4 via the diode D5. Therefore, by opening and closing switches SW1 and SW2, the resistance value inserted into the charging path to capacitor C4 can be changed in three stages (this does not include the state in which both switches SW1 and SW2 are turned on). ). As a result, the light output level of the lighting load 2 can be set in three stages.

[0009] Here, the first dimming control circuit 3:
The second dimming control circuit 4 adjusts the light output level of the lighting load 2 to 1
00%, and when the on-duty of the continuous dimming signal is 0%, the light output level of lighting load 2 is set to 10%.
0%, and the light output level of lighting load 2 is set to 50% when the on-duty of the continuous dimming signal is 100%, and during that time, the on-duty and the light output level are proportional. do. Further, the second dimming control circuit 4 controls both switches SW1 in a state in which the first dimming control circuit 3 sets the light output level of the lighting load 2 to 100%.
, the light output level of lighting load 2 is 100% when SW2 is off, and 80% when only switch SW1 is on.
, is set to 70% when only switch SW2 is on.

0010

[Problems to be Solved by the Invention] In the above configuration, the outputs of the first dimming control circuit 3 and the second dimming control circuit 4 are connected to the resistor R4 and the capacitor that set the time constant of the monostable multivibrator MUL. Since it is input in parallel to the connection point with C4, as shown in Fig. 8, continuous dimming is performed when a stage dimming signal that increases the light output level of lighting load 2 to 80% is input. Assuming that a signal is input, if the on-duty of the continuous dimming signal is 0%, the optical output level is 8.
0%, and the on-duty of the continuous dimming signal is 100%.
In this case, the optical output level will be 40%. Also, if the stage dimming signal is set to 70%, the continuous dimming signal will cause 35%
It becomes possible to control light within a range of ~70%.

That is, in the above configuration, since the upper limit and lower limit of the optical output level that can be controlled by the continuous dimming signal are changed simultaneously by the step dimming signal, the step dimming signal is
The upper limit value of the light output level that can be controlled by the continuous dimming signal cannot be set to 100% except when the setting is 00%. Also, when the upper limit of the optical output level is set to 100%, the lower limit is set to 50%.
For example, it is impossible to satisfy the requirement of setting the lower limit value to 90% and changing the optical output level within a narrow range of 90 to 100%.

Furthermore, as shown in FIG. 9, instead of connecting one end of the resistor R4 to the positive terminal of the DC power source E2, the first
A circuit may also be considered in which the output of the dimming control circuit 3 is applied to the one end of the resistor R4 through the resistors R15 and R16. Each resistor R15, R16 has a switch SW1, S
W2 are connected in parallel, and in this circuit, each resistor R15,
R16 functions as the second dimming control circuit 4, and the switches SW1 and SW2 function as the second dimming setting section 6. That is, the lower and upper limits of the optical output level are set according to the open/closed states of each switch SW1 and SW2, and if this configuration is adopted, the lower limit of the optical output level can be set higher than 50%. It is. For example, as shown in FIG. 10, the lower limit value can be set to 80% or 100%, and since the upper limit value is twice the lower limit value, it is possible to set it to 160% or 200%.

However, if such a circuit configuration is adopted, the output of the high frequency conversion circuit 1 will increase, causing problems such as increased stress on the circuit components and temperature rise, etc. A problem arises in that the life of the lighting load 2 is shortened. The present invention aims to solve the above-mentioned problems, and it is possible to set the upper limit value of the optical output level fixedly, and to change only the lower limit value in stages, so that the lower limit value and the upper limit value can be changed continuously. The purpose of this invention is to provide a lighting load control device that can control light intensity.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a high frequency conversion circuit that converts the output voltage of a DC power supply into a high frequency voltage and applies it to a lighting load, and a high frequency conversion circuit that converts the output voltage of a DC power supply into a high frequency voltage and applies it to a lighting load. A first dimming setting section that continuously sets the light output level of the lighting load, a second dimming setting section that sets the light output level of the lighting load in multiple stages, and a maximum value of the light output level of the lighting load that sets the maximum value of the light output level of the lighting load to a constant value. At the same time, the minimum value is set in multiple stages by the second dimming setting section, and the light output level of the lighting load is set continuously between the minimum value and the maximum value by the first dimming setting section. It also includes a dimming control section that controls the conversion circuit.

[0015]

[Operation] According to the above configuration, the maximum value of the light output level of the lighting load is set to a constant value, and the minimum value is set in multiple stages by the second dimming setting section to minimize the light output level of the lighting load. Since the dimming controller is provided to control the high frequency conversion circuit so that the first dimming setting unit continuously sets between the light output level and the maximum value, the minimum value of the light output level of the lighting load is set at the first dimming setting part. It is set stepwise by the dimming setting section 2, and the maximum value becomes a constant value. Further, the light output level can be continuously changed between the minimum value and the maximum value by the first dimming setting section. the result,
Continuous dimming and stepwise dimming can be performed, and the upper limit of the light output level obtained by continuous dimming can be kept constant at any stage of stepwise dimming.

[0016]

[Embodiment] As shown in FIG. 2, in this embodiment, the output of the second dimming control circuit 4 is inputted to the first dimming control circuit 3 to perform continuous dimming control. The lower limit of the control range in the first dimming control circuit 3 is regulated by the output of the second dimming control circuit 4 that performs dimming control in stages.

The basic configuration of the specific circuit is similar to the conventional configuration shown in FIG. 5, and as shown in FIG. The difference is that the input is input to the dimming control circuit 3, the connection positions of the second dimming control circuit 4 and the second dimming setting section 6 are changed, and a resistor R17 is added. That is, the second dimming setting section 6 is composed of a pair of switches SW1 and SW2, and the second dimming control circuit 4 is constituted by a pair of resistors R15 and R16 connected in series to each switch SW1 and SW2, respectively. . Here, the first dimming control circuit 3 and the second dimming control circuit 4 constitute a dimming control section. Each series circuit of each switch SW1, SW2 and each resistor R15, R16 is connected in parallel with each other, one end of this parallel circuit is connected to the negative pole of DC power supply E2, and the other end is connected to one end of resistor R17 and the opposite terminal of operational amplifier OP2. Connected to the connection point with the inverting input terminal. A resistor R17 is inserted between the output terminal of the operational amplifier OP1 and the non-inverting input terminal of the operational amplifier OP2.

According to this configuration, the terminal voltage of the capacitor C5 increases in proportion to the on-duty of the continuous dimming signal output from the first dimming setting section 5, and the first dimming control The output voltage V0 of the circuit 3 becomes lower as the on-duty of the continuous dimming signal increases. Here, the differential amplifier mainly composed of the operational amplifier OP1 is configured so that the output voltage is 0V when the on-duty of the continuous dimming signal is 100%, and as shown in FIG. Regardless of the open/closed states of SW1 and SW2, when the on-duty of the continuous dimming signal is 100%, the output voltage V0 of the first dimming control circuit 3 becomes 0V. On the other hand, if only the switch SW1 is turned on, the input voltage to the impedance converter consisting of the operational amplifier OP2 changes from the output voltage of the operational amplifier OP1 to the resistors R17 and R.
15, the upper limit of the output voltage V0 of the first dimming control circuit 3 is the voltage divided by the resistors R17 and R1.
It will be regulated by 5. Also, switch SW
Similarly, if only 2 is turned on, the upper limit of the output voltage V0 of the first dimming control circuit 3 is determined by the resistors R17 and R1.
It will be regulated by 6. Both switches SW1
, SW2 are turned on at the same time, as shown in Figure 3, the on-duty of the continuous dimming signal is set to 0 to 0.
When changed within a range of 100%, the lower limit value of the output voltage V0 of the first dimming control circuit 3 becomes 0V, and the upper limit value changes depending on the setting states of the switches SW1 and SW2. Here, both switches SW1 and SW2
The upper limit value of the output voltage V0 is set to be the highest (10 V) when both are off, and the upper limit value of the output voltage V0 is the lowest (1 V) when the switch SW2 is turned on.

As explained in the prior art section, the high frequency conversion circuit 1 converts the output voltage V0 of the first dimming control circuit 3 into
The higher the switch SW is, the lower the light output level of the lighting load 2 is, as shown in FIG.
The upper limit value of the light output level of the lighting load 2 remains constant regardless of the open/close states of switches SW1, SW2, and the lower limit value changes stepwise according to the open/close states of each switch SW1, SW2.

For example, both switches SW1 and SW2
When the on-duty of the continuous dimming signal is changed in the range of 0 to 100% while both are turned off, the output voltage V0 of the first dimming control circuit 3 changes in the range of 0 to 10V, At this time, the light output level of lighting load 2 is 50~
Set it so that it changes within a 100% range. Resistance R
15, R17, when the switch SW1 is turned on, the change range of the output voltage V0 of the first dimming control circuit 3 with respect to the continuous dimming signal is 0 to 6V, and the lighting load 2
The optical output level is set to vary within a range of 70% to 100%. In addition, the resistors R16 and R17 are arranged such that when the switch SW2 is turned on, the change range of the output voltage V0 of the first dimming control circuit 3 in response to the continuous dimming signal is 0 to 1V, and the lighting load 2 is turned on. Set so that the output level is maintained at approximately 100%. As described above, the upper limit value of the optical output level can be kept constant and the lower limit value can be set stepwise.

The other configurations are the same as the conventional configuration shown in FIG. 6, so their explanation will be omitted. In addition, in the above example,
Although the light output level of the lighting load 2 is controlled by changing the on-duty of the continuous dimming signal, a signal that changes the voltage may also be used.
Any type of device may be used as long as it can continuously change the optical output level of the device. Furthermore, although a series type (half-bridge type) inverter circuit is shown as the high frequency conversion circuit 1, the technical idea of the present invention can be applied to an inverter circuit with one switch element (so-called chopper circuit) or a choke-equipped inverter circuit. This does not preclude application to other inverter circuits such as push-pull type inverter circuits. Furthermore, although a method of controlling the on-duty using the monostable multivibrator MUL has been shown as a control method for the switch elements in the inverter circuit, other control methods such as frequency control can also be used.

[0022]

Effects of the Invention As described above, the present invention sets the maximum value of the light output level of the lighting load to a constant value, and sets the minimum value in multiple stages by the second dimming setting section, thereby adjusting the light output level of the lighting load. A dimming control section is provided that controls the high frequency conversion circuit so that the output level is continuously set between the minimum value and the maximum value by the first dimming setting section, so the light output level of the lighting load can be adjusted. The minimum value is set stepwise by the second dimming setting section, and the maximum value becomes a constant value. Also,
The light output level can be continuously changed between the minimum value and the maximum value by the first dimming setting section. As a result, continuous dimming and stepwise dimming can be performed, and the upper limit of the light output level obtained by continuous dimming can be kept constant at any stage of stepwise dimming.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment.

FIG. 2 is a block diagram showing an embodiment.

FIG. 3 is an explanatory diagram of the operation of the embodiment.

FIG. 4 is an explanatory diagram of the operation of the embodiment.

FIG. 5 is a block diagram showing a conventional example.

FIG. 6 is a circuit diagram showing a conventional example.

FIG. 7 is an explanatory diagram of the operation of a conventional example.

FIG. 8 is an explanatory diagram of the operation of a conventional example.

FIG. 9 is a circuit diagram showing another conventional example.

FIG. 10 is an explanatory diagram of the operation of another conventional example.

[Explanation of symbols]

1 High frequency conversion circuit 2. Lighting load 3 First dimming control circuit 4 Second dimming control circuit 5 First dimming setting section 6 Second dimming setting section E1 DC power supply

Claims (1)

[Claims] 1. A high-frequency conversion circuit that converts the output voltage of a DC power supply into a high-frequency voltage and applies the high-frequency voltage to a lighting load, a first dimming setting section that continuously sets a light output level of the lighting load, and a lighting load. a second dimming setting section that sets the light output level of the lighting load to a plurality of stages; and a second dimming setting section that sets the maximum value of the light output level of the lighting load to a constant value and sets the minimum value to a plurality of stages. and a dimming control section that controls the high frequency conversion circuit so that the light output level of the lighting load is continuously set between the minimum value and the maximum value by the first dimming setting section. Characteristic lighting load control device.