JPS6237360Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of a ballast suitable for starting and lighting high-pressure discharge lamps such as high-pressure mercury lamps.
In particular, the present invention relates to an improvement of a low starting current automatic dimming type ballast that suppresses the lamp current at the time of starting a discharge lamp and thus the input current of the ballast and has an automatic dimming function.

In general, a high power factor type automatic dimming type reactor ballast is constructed by connecting a current limiting semiconductor element 2 such as a triax in series to a current limiting reactor 1 such as a choke coil, and the current limiting semiconductor element 2 as shown in FIG. The conduction controller 3 of the element 2 is configured to be operated by a timer 4, and the current-limiting semiconductor element 2 is brought into conduction from a completely conductive state to an arbitrary conduction phase angle after a certain period of time has elapsed after lighting the discharge lamp. This automatically adjusts the brightness of the discharge lamp. 5 is an AC power source, 6 is a power factor correction capacitor, and 7 is a discharge lamp.

Such an automatic dimming type ballast is suitable for use in road lighting, etc., where the light is dimmed and turned on when the traffic volume decreases at night.

By the way, in such a ballast, it is desirable to make the input current at the time of starting the discharge lamp as small as possible compared to the input current at the time of stabilization of the discharge lamp to facilitate the wiring design of the lighting circuit and reduce costs. However, conventionally, a common method for this purpose was to connect a capacitor 8 of approximately the same capacity in parallel with the power factor correction capacitor 6, as shown by the dotted line in Figure 1, to reduce the lagging current in the circuit. There is. but,
Using such means requires a plurality of capacitors or a large capacitor to replace them, which not only increases the size of the entire device but also increases the cost. Furthermore, an extremely large phase-advanced current flows through the capacitor when there is no load, which has a negative effect on the power supply.

The object of the present invention is to provide a low starting current automatic dimming type ballast that eliminates the above-mentioned drawbacks. In FIG. 2, 1 is an AC power supply, 2 is a current limiting reactor such as a chiyoke coil, and 3 is a discharge lamp such as a high-pressure mercury lamp. Further, 4 is a current-limiting semiconductor element such as a triax connected in series with the current-limiting reactor 2, 5 is a conduction controller for the current-limiting semiconductor element 4, 6 is an electronic timer transmitting circuit composed of IC elements, etc. This is a frequency dividing circuit that divides the frequency of the signal from the oscillation circuit, and is connected so that the output signal of the frequency dividing circuit 7 is supplied to the conduction controller 5.

Reference numeral 8 denotes a secondary no-load voltage detection circuit, which resets the frequency dividing circuit 7 when the discharge lamp 3 does not start or goes out. 9 is a power factor correction capacitor.

Next, the operation of this circuit will be explained. First, when the power source 1 is turned on, current flows to the discharge lamp 3 via the current limiting reactor 2 and the current limiting semiconductor element 4, and the discharge lamp 3 starts. At this time, since the current-limiting semiconductor element 4 is conducting at a constant conduction phase angle, the current-limiting semiconductor element 4 and the current-limiting reactor 2 change the lamp current at the time of starting the discharge lamp to the lamp current at the stable time. about
It is limited to an extremely low value of around 130% or less. On the other hand, at the same time as the power supply 1 is turned on, the electronic timer transmitting circuit 6 also starts operating and continues to send a signal to the frequency dividing circuit 7, for a preset time, for example, 7 to 8 minutes, taking into consideration the time it takes for the discharge lamp 3 to stabilize. When the current limiting semiconductor element 4 has passed, a signal is sent from the frequency dividing circuit 7 to the conduction controller 5, and the conduction phase angle of the current limiting semiconductor element 4 is returned to approximately zero, and the current limiting function of the current limiting semiconductor element 4 is reduced or stopped. Therefore, the discharge lamp 3 maintains normal lighting almost only by the current limiting reactor 2.

In this way, when the normal lighting continues and an arbitrary period of time has elapsed, the signal obtained by dividing the oscillation signal of the electronic timer into several orders is again sent to the conduction controller 5, and the current-limiting semiconductor element 4 changes to an arbitrary conduction state. Since conduction occurs at the phase angle, the discharge lamp 3 is lit in a dimmed state. Figure 3 shows the change in the effective value of the ballast input current during the above operating process.
Point B indicates the point in time when the current limiting function of the current limiting semiconductor element is stopped, and point B indicates the point in time when the dimming state is entered. In addition,
If the discharge lamp fails to start or goes out during the operation for some reason, the secondary no-load voltage detection circuit operates to reset the frequency dividing circuit.

Figure 4 shows a specific embodiment of the present invention.
E is an AC power source, Z is a current limiting reactor, Th is a triac, L is a discharge lamp, and _C1 is a power factor correction capacitor. Resistor R ₁ , diode D ₁ , zener diode ZD ₁ and capacitor C ₂ are electronic timer
It constitutes the FT's DC power supply circuit, and resistor _R2 prevents overcurrent and controls the current to the photothyristor FS. Capacitor C ₃ and resistor R ₃ constitute a CR circuit for transmitting electronic timer ET, and thyristor SCR receives a signal from electronic timer ET and supplies DC power to photothyristor FS. Transistor Tr ₁ is a resistor when the discharge lamp L is unloaded.
The trigger element SBS ₁ is triggered by the voltage division ratio of R ₁₀ and R ₁₁ , and the DC voltage generated by the circuit consisting of the diode D ₂ , capacitor C ₄ , and Zener diode ZD ₂ is introduced into the base via the resistor R ₆ . The reset terminal of the electronic timer ET is short-circuited. When the discharge lamp L is started, the phase of the triax Th is controlled by a trigger circuit consisting of resistors R ₁₃ , R ₁₄ , a capacitor C ₅ and a trigger element SBS ₂ , and when the electronic timer ET is activated, the resistor R is controlled by a photothyristor FS. ₁₄ is short-circuited and phase control is released. Resistor R ₁₅ and capacitor C ₆ form a surge absorption circuit. The flip-flop circuit FF divides the output signal from the electronic timer ET to generate a several-hour signal, operates the transistor Tr ₂ , excites the relay coil Ry, opens the relay contact ry, and delays and adjusts the conduction phase angle of the triac Th. Bring to light state. Since the operation of this circuit can be easily understood from the explanation of the operation in FIG. 2, the explanation thereof will be omitted.

As is clear from the above explanation of the configuration and operation, the low starting current automatic dimming type ballast according to the invention of the present invention uses a current limiting semiconductor element connected in series with a current limiting reactor to control the lamp current at the time of starting the discharge lamp. The restriction is released after a certain period of time when the discharge lamp reaches a stable state, and the discharge lamp is dimmed and lit by the current-limiting semiconductor element after an arbitrary period of time has elapsed, and this series of operations is performed by one electronic A timer is used to perform the process regardless of changes in the characteristics of the discharge lamp.

In addition, the ballast according to the present invention is called a so-called electronic ballast in terms of its circuit configuration because it connects a current limiting reactor, a current limiting semiconductor element, and a discharge lamp in series, and controls the phase of the current limiting semiconductor element. Although they are similar, they are completely different in content. In other words, in the case of electronic ballasts, part of the current-limiting action of the current-limiting reactor is borne by the semiconductor element, and the number of windings in the current-limiting reactor is reduced to reduce the size and weight of the ballast. Whereas both the reactor and the semiconductor element perform a current limiting action, and this is done in response to changes in the characteristics of the discharge lamp, the invention of the present invention reduces the starting input current to the ballast without using a phase advancing capacitor. At the same time, the purpose is to have a dimming function as well.The current-limiting semiconductor element has a current-limiting effect only at the time of starting and dimming the discharge lamp, and can do this regardless of changes in the characteristics of the discharge lamp. It is something to do.

The effects of the present invention with the above configuration are as follows. First, unlike conventional low starting current type ballasts, there is no need to use multiple capacitors or large capacitors, so the entire device can be made extremely compact. Second, since the semiconductor element for current limiting and the semiconductor element for dimming are used together, and they are controlled by a single electronic timer, the number of parts is relatively small, and there is no disadvantage in terms of cost, and the entire device is Since it can be made more compact and contactless, the safety and reliability of the device can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional automatic dimming type ballast, Fig. 2 is a circuit diagram of a low starting current automatic dimming type ballast according to the present invention, and Fig. 3 is a change characteristic of input current in the ballast. FIG. 4 is a circuit diagram of a specific embodiment of the present invention. In Fig. 2, 1... AC power supply,
2... Current limiting reactor, 3... Discharge lamp, 4... Current limiting semiconductor element, 5... Continuity controller, 6... Electronic timer transmission circuit, 7... Frequency dividing circuit, 8... Secondary no-load Voltage detection circuit.

Claims (1)

[Scope of utility model registration request] A current-limiting semiconductor element is connected in series with the current-limiting reactor of the discharge lamp, and the conduction controller of the current-limiting semiconductor element is controlled for a certain period of time by an electronic timer regardless of changes in the characteristics of the discharge lamp, so that the discharge during that period is controlled. When starting a lamp, the lamp current is limited to a certain value or less compared to the stable lamp current, and after the above period of time, the current-limiting function of the current-limiting semiconductor element is reduced or stopped, so that the discharge lamp can be operated using only the current-limiting reactor. At the same time, after an arbitrary time, the signal obtained by dividing the signal of the electronic timer into several orders is given again to the conduction controller of the current-limiting semiconductor element, and is emitted at an arbitrary conduction phase angle. A low starting current automatic dimming type ballast characterized by being configured to control the dimming of an electric light.