JP2003031382A - Lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To light an alternating current lamp and a direct current lamp with simple constitution. SOLUTION: This lamp lighting device is provided with a bridge circuit 6 composed of a first switching element 13a for switching connection between a plus input terminal on the DC power supply 4 side and a first output terminal on the lamp 2 side, a second switching element 13b for switching connection between a minus input terminal on the DC power supply 4 side and the first output terminal on the lamp 2 side, a third switching element, 13c for switching connection between the plus input terminal on the DC power supply 4 side and a second output terminal on the lamp 2 side, and a fourth switching element 13d for switching connection between the minus input terminal on the DC power supply 4 side and the second output terminal on the lamp 2 side; and a switching control means 7 for controlling the on/off switching of the first to fourth switching elements 13a-13d constituting the bridge circuit 6. AC voltage or DC voltage is outputted to the lamp 2 side by controlling the switching of the bridge circuit by the switching control means 7.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp lighting device for lighting a lamp used in, for example, a liquid crystal projector. 2. Description of the Related Art For example, there is a liquid crystal projector for displaying an image using liquid crystal. In this liquid crystal projector, clearer images can be displayed on the screen by making the illumination as bright as possible. For this reason, in a liquid crystal projector, a high-intensity discharge lamp such as a halogen lamp, a metal halide lamp, or a xenon lamp is used as a light source. Further, the liquid crystal projector includes a lamp lighting device for lighting such a discharge lamp. In the above-mentioned liquid crystal projectors, there are a light source using an AC (alternating current) lamp and a light source using a DC (direct current) lamp as a light source. It was necessary to prepare a lamp lighting device corresponding to the lamp. For this reason, the conventional lamp lighting device is largely limited by the lamp used, and it is necessary to prepare separate service parts for the same lamp output depending on whether the lamp is an AC lamp or a DC lamp. There was a problem that parts management became complicated. Further, in the conventional lamp lighting device, since it is impossible to use the AC lamp and the DC lamp, it is necessary to meet the demands of the market in the event that one of the lamps has a problem or shortage of delivery. However, there is a problem that set production of a liquid crystal projector or the like is restricted. Accordingly, the present invention has been proposed in view of such conventional circumstances, and has as its object to provide a lamp lighting device capable of lighting an AC lamp and a DC lamp with a simple configuration. . A lamp lighting device according to the present invention for attaining this object is for lighting an AC lamp or a DC lamp, and includes a positive input terminal on the DC power supply side and a lamp. A first switching element for switching a connection between the first output terminal on the DC side and a second switching element for switching a connection between a negative input terminal on the DC power supply side and a first output terminal on the lamp side. A third switching element for switching the connection between the positive input terminal on the DC power supply side and the second output terminal on the lamp side, and between the negative input terminal on the DC power supply side and the second output terminal on the lamp side A bridge circuit having a fourth switching element for switching the connection between the first and second switching elements, and switching control means for switching and controlling the first to fourth switching elements of the bridge circuit. Is provided. When the AC lamp is turned on, the switching control means turns on the first switching element and the fourth switching element and turns off the second switching element and the third switching element. , The first switching element and the fourth switching element are turned off, and the second switching mode in which the second switching element and the third switching element are turned on is alternately repeated, and the DC lamp is turned on. At this time, the switching control means performs control for fixing the switching mode to one of the first switching mode and the second switching mode. As described above, in the lamp lighting device according to the present invention, when lighting the AC lamp, the switching control means turns on the first switching element and the fourth switching element, and switches the second switching element and the fourth switching element. A first switching mode in which the third switching element is turned off;
And the fourth switching element are turned off, and the second switching mode in which the second switching element and the third switching element are turned on is alternately repeated. The DC voltage can be converted to an AC voltage and output to the lamp side. When the DC lamp is turned on, the switching control means performs control to fix the switching mode to one of the first switching mode and the second switching mode.
The DC voltage input from the DC power supply can be output to the lamp. Therefore, in this lamp lighting device, the AC lamp and the DC lamp can be lighted with a simple configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lamp lighting device to which the present invention is applied will be described in detail with reference to the drawings. A lamp lighting apparatus 1 according to the present invention shown in FIG. 1 is for lighting a discharge lamp 2 used for a liquid crystal projector, for example. The liquid crystal projector turns on the discharge lamp 2 as a light source,
An image displayed on a liquid crystal display panel (LCD) is projected onto a projection lens, and an enlarged image is displayed on a screen through the projection lens. As the discharge lamp 2, for example, a high-intensity discharge lamp such as a halogen lamp, a metal halide lamp, a xenon lamp, or a high-pressure mercury lamp is used. Alternating current)
There are lamps and DC (direct current) lamps. The lamp lighting device 1 to which the present invention is applied is capable of lighting these AC lamps and DC lamps with a simple configuration. Specifically, the lamp lighting device 1 includes a DC power supply circuit 4 that rectifies an AC current supplied from a commercial power supply 3 and converts the AC current into a DC current, and a step-down DC voltage input from the DC power supply circuit 4. A full-bridge circuit 6 to which a stabilized DC voltage is input from the down-converter 5, a switching control circuit 7 for controlling switching of the full-bridge circuit 6, and an igniter 8 for starting the discharge lamp 2; Full bridge circuit 6 to igniter 8
, A voltage detector 9 for detecting a current supplied from the full bridge circuit 6 to the igniter 8, and a power detector for detecting a current supplied from the full bridge circuit 6 to the igniter 8. The power detector 11 and the down converter 5 are connected to a PWM (Pulse Width Modulation:
And a PWM controller 12 for controlling (pulse width modulation). The DC power supply circuit 4 is composed of, for example, an active filter and the like.
After the C current is rectified and converted into a DC current, the DC current is output to the down converter 5 described above. The DC voltage output at this time is, for example, about 300 V to 400 V. The down-converter 5 switches the DC voltage input from the DC power supply circuit 4 at about 50 to 100 kHz, and switches the DC voltage required for lighting the discharge lamp 2 to 50 to 100 kHz.
Convert to a DC voltage of about 100V. As shown in FIGS. 1 and 2, the full bridge circuit 6 serves as a switching element between the plus input terminal (+) on the down converter 5 side and the first output terminal (S1) on the igniter 8 side. , A negative input terminal (-) on the down converter 5 side, and a first output terminal (S) on the igniter 8 side.
A second transistor 13 for switching the connection between 1)
b, a third transistor 13c for switching connection between a plus input terminal (+) on the down converter 5 side and a second output terminal (S2) on the igniter 8 side, and a minus input terminal ( -) And a fourth transistor 13d for switching the connection between the igniter 8 side second output terminal (S2). The first to fourth transistors 13a to 13d constituting the full bridge circuit 6 are respectively connected to a switching control circuit 7, and based on a control signal from the switching control circuit 7, O
N / OFF switching is controlled. The switching elements constituting the full bridge circuit 6 are not limited to the above-described first to fourth transistors 13a to 13d.
It is also possible to use an ld Effect Transistor (field effect transistor) or the like. The switching control circuit 7 includes the discharge lamp 2
When turning on the AC lamp, the full bridge circuit 6
On the other hand, the first transistor 13a and the fourth transistor 13d are turned on (ON), and the second transistor 13b and the third transistor 13c are turned off (OFF).
A first switching mode, and a first transistor 13a
And turning off the fourth transistor 13d,
Second transistor 13b and third transistor 13
Control is performed to alternately repeat the second switching mode in which c is turned on (ON) at a predetermined switching frequency. When the DC lamp is turned on as the discharge lamp 2, the switching control circuit 7 controls the full bridge circuit 6 to perform one of the first switching mode and the second switching mode. Control to fix the switching mode. The igniter 8 is operated when the lamp is started.
The discharge lamp 2 is turned on by applying a pulse voltage of about kV to the discharge lamp 2. After the lamp is turned on, 50 to 100 V is applied from the full bridge circuit 6 described above.
A voltage of the order is applied to the discharge lamp 2 through the igniter 8. Thereby, the lighting of the discharge lamp 2 is maintained. The voltage detector 9 measures a voltage value applied from the full bridge circuit 6 to the igniter 8 and outputs the measurement result to the power detector 11. The current detector 10 measures a voltage value applied from the full bridge circuit 6 to the igniter 8 and outputs the measurement result to the power detector 11. The power detection unit 11 calculates a power value from the voltage value and the current value measured by the voltage detection unit 9 and the current detection unit 10, and outputs the calculation result to the PWM controller 12. The PWM controller 12 includes the power detector 1
Based on the power value calculated in step 1, the down converter 5 is subjected to PWM control so as to maintain a constant power. The lamp lighting device 1 configured as described above
Then, when lighting the AC lamp as the discharge lamp 2,
Based on a control signal from the switching control circuit 7, the first transistor 13a and the fourth transistor 13d
In a first switching mode in which the second transistor 13b and the third transistor 13c are turned off, and a first transistor 13a and a fourth transistor 13d.
Is turned off and the second switching mode in which the second transistor 13b and the third transistor 13c are turned on is alternately repeated at a predetermined switching frequency. In this case, in the first switching mode, a DC voltage is input from the plus input terminal (+) of the down converter 5 to the first output terminal (S1) of the igniter 8 via the first transistor 13a. Then, the second output terminal (S) on the igniter 8 side via the fourth transistor 13d
From 2), a DC voltage is output to the negative input terminal (-) of the down converter 5 side. On the other hand, in the second switching mode, a DC voltage is input from the plus input terminal (+) on the down converter 5 side to the second output terminal (S2) on the igniter 8 side via the third transistor 13c. , The second transistor 1
3b, a first output terminal (S1) on the igniter 8 side
Outputs a DC voltage to the negative input terminal (−) of the down converter 5. By alternately repeating the first switching mode and the second switching mode at a predetermined switching frequency, the DC voltage input from the down converter 5 is converted into an AC voltage of about 90 to 600 cycles. Then, it can be output to the igniter 8. Thus, the AC lamp can be turned on. In the lamp lighting device 1, when the DC lamp is turned on as the discharge lamp 2, the first switching mode and the second switching mode are switched based on a control signal from the switching control circuit 7. Among them, control for fixing to one of the switching modes is performed. In this case, the DC voltage input from the down converter 5 can be output to the igniter 8. Thus, the DC lamp can be turned on. As described above, in the lamp lighting device 1, it is possible to light the AC lamp and the DC lamp with a simple configuration. That is, the lamp lighting device 1 is configured to convert a DC voltage normally supplied from the DC power supply circuit 4 into an AC voltage, output the AC voltage to the discharge lamp 2, and light the AC lamp as the discharge lamp 2. However, the switching control circuit 7 controls the full bridge circuit 6 so as to fix the switching mode to one of the first switching mode and the second switching mode, thereby reducing the DC voltage. It is possible to output to the discharge lamp 2 as it is and to turn on the DC lamp which is the discharge lamp 2. Further, in the lamp lighting device 1, the switching between the AC voltage and the DC voltage output to the discharge lamp 2 can be easily and quickly performed depending on whether the discharge lamp 2 to be used is an AC lamp or a DC lamp. It is possible. Here, when starting the AC lamp, it is desirable to apply a DC voltage until the lighting of the AC lamp is stabilized. In this case, in the lamp lighting device 1, the switching control circuit 7 described above can appropriately and quickly perform the mode switching in which the DC voltage is applied at the time of starting the AC lamp and the AC voltage is applied after the lamp is turned on. It becomes. Further, in this lamp lighting device 1, since an AC lamp and a DC lamp can be used, it is possible to use the discharge lamp 2 depending on whether the discharge lamp 2 is an AC lamp or a DC lamp.
There is no need to prepare separate service parts and the like, and it is possible to solve the problem that parts management becomes complicated. Specifically, regardless of whether the discharge lamp 2 used is an AC lamp or a DC lamp,
It is possible to use a common board mount checker. This makes it possible to reduce the production cost and the like as compared with the related art. Further, in the lamp lighting device 1, even if a failure or a shortage of delivery occurs in one of the discharge lamps 2 of the AC lamp and the DC lamp, the lamp can be diverted to the other discharge lamp 2. Since it is possible, it is possible to solve the problem that set production is limited in products such as the liquid crystal projector described above. In an electronic apparatus such as a liquid crystal projector on which the lamp lighting device 1 is mounted, whether the discharge lamp 2 to be used is an AC lamp or a DC lamp is determined, and based on the determination result, the above-described switching is performed. Mode switching by the control circuit 7, that is, switching between the AC voltage and the DC voltage output to the discharge lamp 2 is performed. As a method of determining whether the discharge lamp 2 to be used is an AC lamp or a DC lamp, the shape of the discharge lamp 2 (shape of the lamp holder) or the like depends on the type of the discharge lamp 2 to be mounted on the electronic device. And a method of detecting such a difference in shape. Further, in the lamp lighting device 1, not only an electric circuit switching control means such as the switching control circuit 7 described above, but also a relay 14 as shown in FIG. It is also possible to adopt the configuration used. In this case, in the lamp lighting device 1, instead of the switching control circuit 7 described above, the relays 14 are used to switch the contacts with the first to fourth transistors 13 a to 13 d constituting the full bridge circuit 6.
Switching between the AC voltage and the DC voltage output to the discharge lamp 2 can be performed easily and in a short time. As described in detail above, according to the lamp lighting device of the present invention, it is possible to light an AC lamp and a DC lamp with a simple configuration.
It is possible to easily and quickly switch between the AC voltage and the DC voltage output to the lamp side.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one configuration example of a lamp lighting device to which the present invention is applied. FIG. 2 is a main block diagram showing a configuration of a full bridge circuit of the lamp lighting device. FIG. 3 is a main block diagram showing a modification of the lamp lighting device. [Description of Signs] 1 lamp lighting device, 2 discharge lamp, 3 commercial power supply,
4 DC power supply circuit, 5 down converter, 6 full bridge circuit, 7 switching control circuit, 8 igniter,
Reference Signs List 9 voltage detector, 10 current detector, 11 power detector, 12 PWM controller, 13a first transistor, 13b second transistor, 13c third transistor, 13d fourth transistor, 14 relay

Claims (1)

Claims 1. A lamp lighting device for lighting an AC lamp or a DC lamp, wherein a connection between a positive input terminal on the DC power supply side and a first output terminal on the lamp side is provided. A first switching element for switching, a second switching element for switching connection between a negative input terminal on the DC power supply side and a first output terminal on the lamp side, a positive input terminal on the DC power supply side and a lamp side And a fourth switching element for switching the connection between the negative input terminal on the DC power supply side and the second output terminal on the lamp side. And a switching control means for switching and controlling the first to fourth switching elements of the bridge circuit. When you light, the above-mentioned switching control means,
A first switching mode in which the first switching element and the fourth switching element are turned on and the second switching element and the third switching element are turned off; and a first switching mode in which the first switching element and the fourth switching element are turned off. And a second switching mode in which the second switching element and the third switching element are turned on and the second switching mode is turned on alternately. When the DC lamp is turned on, the switching control is performed. The means
Of the first switching mode and the second switching mode,
A lamp lighting device that performs control for fixing the switching mode to one of the switching modes.