JPS6256639B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a constant input light control device for a discharge lamp.

Conventionally, the phase control method shown in FIG. 1 has been widely known as a lighting method for HID lamps. This method uses an AC control element and current limiting inductance connected in series with the HID lamp L to perform the current limiting function of the lamp current, so the current limiting inductance V・A
It has the advantage of reducing capacity. Furthermore, the conduction phase of the AC control element has conventionally been determined by the method of detecting the voltage across the lamp as shown in FIG. However, with this method, the control section cont
In addition, a block circuit was required to protect the control unit from the kick voltage at the time of starting the high-pressure sodium lamp. This means that the control
The conduction heat and high-pressure pulses that the cont receives from the HID lamp L cause quality deterioration, and there is also a drawback that the number of component parts is large, resulting in a large cost increase. Another method for determining the conduction phase of an AC control element is to detect the lamp current.
This method connects a sensing element in series with the lamp,
Furthermore, it is necessary to provide insulation from the control section, which also has the drawbacks of increasing costs and increasing the size.

On the other hand, due to the demands of the era of systemization and sophistication, it became necessary for lighting devices to have the ability to control the lighting state using digital signals. This means that computer-based system control such as flashing/dimmer pattern control or scheduling is required from the perspective of energy conservation, and with the remarkable progress in IC and LSI technology, microcontrollers are becoming available at low cost. This is because the. Against this background, lighting control methods suitable for digital control have been considered, one of which is a method that detects the lamp current phase and controls the conduction phase of the AC control element using the detected signal (hereinafter referred to as this method). There is a method called the phase detection method).

The present invention is a lighting device using a phase control method that determines the conduction phase of an AC control element connected in series with a discharge lamp according to the lamp current phase of the discharge lamp, and does not turn off even for lamps with high lamp voltage. An object of the present invention is to provide a constant input dimming lighting device for a discharge lamp that can stably dim the light and easily change the dimming ratio.

The main circuit of the phase detection method described above is shown in FIG. In FIG. 2, 1 is an HID lamp, 2 is a control section, 3 is a main chain, 4 is an AC control element, and 5 is a sub chain. As can be seen from FIG. 2, the control section 2 receives the voltage across the AC control element 4 and the power supply voltage, and detects the phase of the lamp current. As an example of this detection method, the terminals in the control section in Fig. 2,
A method may be adopted in which a transformer having an insulated secondary winding is connected between the two terminals and the voltage across the secondary winding is detected. In this way, when the lamp current crosses zero, it is turned off by the self-off function of the AC control element, and the lamp current is applied to both ends of the primary side of the transformer.
Since a leading phase voltage that is advanced by 90 degrees is generated and this voltage is induced in the insulated secondary winding, the zero-crossing phase of the lamp current becomes the rising phase of the voltage across the secondary winding. If the reference phase is the zero-crossing phase of the power supply voltage, the control section can detect the lamp current phase every half cycle of the power supply.

FIG. 3 is a basic principle diagram of the phase detection method necessary for constant input starting control (input current is less than the rated input current during the lamp starting process). A is immediately after starting, b is at rated time, e is the power supply voltage waveform, and i is the lamp current. Immediately after the HID lamp starts, the equivalent conductance inside the lamp is much larger than at the rated value, so a large amount of lamp current tends to flow. Therefore, when this lamp current is reduced to the value required for constant input starting, the zero cross phase T of the lamp current (here, the off phase of the AC control element)
It can be seen that the off-period ΔT of the AC control element is significantly different from immediately after starting and at the rated time. FIG. 4 illustrates the relationship between T and ΔT during the entire process of starting the HID lamp. In other words, if the control that satisfies the conditions shown in FIG. 4 is performed, constant input starting can be obtained. In other words, depending on the lamp current phase T,
This means that the off period ΔT of the AC control element is controlled so as to satisfy the relationship shown in FIG.

In a constant input lighting device that performs such control,
Consider how to control the dimming state. To switch to dimming, conduction phase θ (=T+△T) of AC control element
It is necessary to appropriately delay the rated value.
After that, the phase relationship T and △ corresponding to the desired dimming ratio
It becomes possible to obtain a stable dimming state by performing control so as to satisfy T.

The present invention is characterized in that a dimming function is added to a constant input lighting device using phase control that determines the off period ΔT of an AC control element according to the lamp current phase (T).

There are two major issues with dimming control. The first is that the lamp does not go out during switching, and the second is that the dimming state is controlled to the desired dimming ratio. Therefore, let us consider the fact that the lamp does not turn off during the first switching. First, if we examine the relationship between T and ΔT at the time of switching, we will find that it is as shown in FIG. If point B is the relationship at the rated value, increasing or decreasing the conduction phase θ (=T + △T) from this point will result in a position on the straight line or extension line (on the broken line in Figure 5) of ○Ro - ○C during switching. This means that there is a relationship between T and △T. To investigate, use the circuit shown in Figure 6 to instantly switch the conduction phase θ of the AC control element from the rated state, and then calculate the voltage across the AC control element (V _TR
c ) was measured using a synchroscope, with the rising phase of V _TRc being T and the period from T to the falling phase of V _TRc being ΔT. The circuit constants are a 400W mercury lamp (lamp voltage 149V), main chain impedance voltage 80V/3.3A, secondary chain impedance voltage 68V/0.375A, power supply voltage.
200V, and the rated output of a 400W mercury lamp is 400W in Figure 5.

The phase relationship T and △T at the time of dimming switching satisfies the broken line in Figure 5, but if △T becomes too large, the lamp current will be throttled down too much, the restriking portion of the lamp voltage will become large, and the lamp will go out. Therefore, ΔT cannot be changed too much.

For the above reasons, it is clear that the dimming control condition needs to satisfy ○C if the switching point is ○C, for example.

Next, the control conditions for controlling the dimming ratio to be aimed at, which is the second issue, will be explained. In Figure 6, the conduction phase θ is gradually increased over a period of time from the rated time.
When the phase relationship T and ΔT in each stable state up to a dimming ratio of 60% are measured by the method described above, it was found that they lie on the chain line shown in FIG. 5. From this, in order to control the dimming state with a 60% dimming ratio,
This shows that it is necessary to perform phase control that ultimately satisfies the two points.

The dimming control condition needs to satisfy the above two phase control conditions, that is, the phase relationship during dimming switching (dashed line in FIG. 5) and the phase relationship when dimming is stable (dashed line in FIG. 5).

Therefore, the dimming control condition of the present invention satisfies ◯C, and also defines a function of T and ΔT that passes through one point of the chain line according to the dimming ratio. For example, 70%
When performing dimming control to the dimming ratio, it is sufficient to use a function simply connecting ○C and ○H with a straight line as a control condition, and to switch from a constant input control condition of a straight line connecting ○A and ○B. 60%
If you want to set the dimming ratio, just select the straight line connecting ○C and ○D as the control condition.

Embodiment A constant input dimming control method using a straight line connecting ○C and ○D as a control condition will be explained with reference to FIGS. 7 and 8. The periods of the first clock and the second clock are T
and the minimum controllable phase angle unit of ΔT. After power-on, a constant input condition is achieved while the lamp is in the starting process. In this operation, when the dimming switch is off, an "L" output is output to the INV output via the transistor _Q1 . As a result, the initial value for the constant input condition, the addition counter start phase (T ₀ ), and the period of the first clock are selected.

The phase angle T ₀ lags behind the power supply zero cross phase,
The addition counter sets the digital value of the second clock corresponding to ΔTO to an initial value and starts counting the first clock. When the zero-crossing phase of the lamp current is detected, the delay circuit latches (holds) the contents of the addition counter. Then, at a phase delayed by a phase angle T ₀ from the next power supply zero cross phase, the addition counter sets its initial value and starts counting, at the same time.
The subtraction counter sets the counter contents latched by the delay circuit to an initial value, and continues to set the counter contents until the zero-crossing phase of the lamp current. That is, the initial value of the subtraction counter is a value corresponding to the lamp current phase T of the previous half cycle. Therefore, the subtraction counter starts subtracting the second clock at the zero-crossing phase of the lamp current, and a trigger pulse is generated at the phase when the content of the subtraction counter becomes zero. In this way, the constant input condition a is achieved, and the lamp reaches its rated lighting.

Next, at any time, when the dimmer switch closes,
_Q0 turns on, the INV output is inverted, and changes from "L" to "H". As a result, the period of the initial value addition counter start phase (T ₁ ) first clock for the dimming condition is selected. At this time, T and △T shift to ◯C, completing the dimming switching. After that, the lamp voltage decreases in the opposite direction to the starting process, the lamp current tries to increase, the lamp current phase tends to lag, and the lamp is controlled toward the ○2 point. Then, the desired dimming ratio can be obtained stably at the two points.

This time, when the dimming SW opens, the control condition becomes b.
The lighting state changes from to a, and the lighting state can easily attain the rated lighting.

As is clear from the model shown in FIG. 7, the phase detection method shown in FIG. 2 is capable of two-line control, and enables unprecedented two-line dimming of HID lamps. Moreover, if digital control is performed, which is advantageous with the phase detection method, it can be combined with a digital system or a microcomputer system, and dimming pattern control can be easily performed, and HID lighting can also have a large power saving effect.

In addition, in dimming control, as is clear from the explanation of Figure 5, the selection of the dimming ratio is determined by the slope of the control line or the phase relationship at the time of switching, so the dimming ratio can be easily changed and multi-stage dimming or It also has the effect of continuous dimming. Dimming control has become possible in the lighting device. However, there are still drawbacks to obtaining brightness and color rendering properties that are appropriate for each situation with only a single level of dimming. In other words, recently there has been a demand for lighting with high efficiency and high color rendering by lighting two different types of lamps, such as high-pressure sodium lamps and multi-halogen lamps. In this case, there is an advantage that arbitrary color rendering properties can be obtained by adjusting the dimming ratio of the lamps. Therefore, the dimming level is not single, but multiple levels are desired, and the following embodiment is a means for obtaining this multi-level dimming. FIG. 10 is an explanatory diagram when performing a plurality of dimming conditions.

From Fig. 5, it is clear that when the slope of the dimming control conditions is the same, the dimming conditions for dimming ratios of 80%, 70%, and 60% are as shown in b, c, and d, respectively, in Fig. 10. . An embodiment for this purpose is shown in FIG.

Switches S ₁ , S ₂ , and S ₃ are switches for dimming 60%, 70%, and 80%, respectively, and enter dimming when turned on. Also, when any of the switches S ₁ , S ₂ , and S ₃ is on, all other switches are off. Now, if only switch _S1 is turned on, the transistor
Only _Q1 is turned on, and the output of inverter INV1 becomes "H". Therefore, the value in the initial value circuit is
01101110 (6E in hexadecimal). When S ₁ is off, that is, in the rated lighting state, this value is 01001110
(4E in hexadecimal) Therefore, the initial value suddenly becomes large.
This results in △T ₀ increasing to △T ₃ .
In addition, the outputs of switches S ₁ , S ₂ , and S ₃ are each input to an OR circuit, which monitors whether the switches are on or not.
When any of the switches is turned on (that is, when dimming switching occurs), the period of the first clock is switched to dimming. This changes at the same cycle no matter which switch is turned on. Therefore, dimming conditions b, c,
d has the same slope and is different from the constant input condition. This slope does not need to be particularly different from the constant input condition, but increasing the slope is more effective in preventing fading during dimming switching.

According to this embodiment, the dimming ratio can be easily changed by setting the initial value, and multistage dimming is possible. From this, the mixing ratio of different types of lamps such as high-pressure sodium lamps and multi-halogen lamps can be set arbitrarily.
HID lighting can be easily applied to indoor lighting.

Furthermore, since the dimming ratio can be set using digital values, it is also suitable for microcomputer control, and has the potential to become the core of future system products.

[Brief explanation of the drawing]

Figure 1 shows the conventional phase control system, Figure 2 shows the main circuit of the phase detection system of the present invention, Figure 3 A and B show the basic diagram of the phase detection system for constant input starting control, and Figure 4 shows the lamp current The relationship between the zero cross phase T and the OFF period of the AC control element, Figure 5 shows the relationship between the zero cross phase T and the off period of the AC control element, at the rated time, 60%, 70%, 80%.
The relationship between T and △T during % dimming, Figure 6 shows T and △T
Figure 7 is a model of the phase detection method, Figures 8 and 9 are diagrams for explaining the optical input dimming control method, and Figure 10 is for explaining multiple dimming conditions. FIG. 11 shows another embodiment of the present invention. 1...HID lamp, 2...Control unit, 3...Main chain yoke, 4...AC control element, 5...Sub-chiyoke.

Claims (1)

[Scope of Claims] 1. A control circuit that connects an AC control element, a current limiting impedance, and a lamp in series to a commercial power supply, and controls the conduction phase of the AC control element every half cycle of the power supply in accordance with the lamp current phase. In the discharge lamp lighting device, the control circuit includes an element that stores at least two or more correspondences between lamp current phases and conduction phases of the AC control element to be controlled, and After the power is turned on, the phase is always controlled by a specific one of the above-mentioned correspondence relationships, and when an external switch signal is input, another correspondence relationship is selected in response to the switch signal instead of the above-mentioned specific correspondence relationship. 1. A discharge lamp constant input dimmer lighting device, characterized in that it has a control circuit which is controlled by the control circuit. 2. A discharge lamp according to claim 1, wherein a plurality of desired dimming switches are provided, and when one of the switches is turned on, the initial position of dimming is determined accordingly. Constant input dimmer lighting device.