JP3600127B2 - LCD projector - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device including a plurality of projection lamps, each projection lamp configured to project an entire screen.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a liquid crystal projector, high brightness of a projection lamp has been attempted to improve brightness performance. Accordingly, the driving power supply capacity of the projection lamp has been increased. As a result, the transient current when the projection lamp is turned on has become extremely large.
[0003]
On the other hand, the present inventor has developed a four-lamp type in which four projection lamps are provided in order to realize high brightness in addition to improving the performance of the projection lamp alone. This is such that the projection light from the four projection lamps is combined by an optical system so that each of the projection light from each projection lamp projects the entire screen. Therefore, when there is a lamp that does not light among the four projection lamps due to some problem, a specific screen area is not projected, and the brightness of the entire screen is reduced.
[0004]
In the above-described four-lamp system, if all the projection lamps are turned on at the same time, four transient currents flowing at the time of lighting will flow at the same time, and it is necessary to secure the maximum current as the power supply capacity. Therefore, a capacitor having a capacity capable of flowing a transient current four times as large as that of a single lamp type is required.
[0005]
Furthermore, in the case of a single-lamp system, if there was no lighting during projection, there was no other way than to stop the projection and to deal with it. In some cases, it is possible to continue projection with another normally lit lamp.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a liquid crystal projector having a plurality of projection lamps, each of which is configured to project the entire screen, thereby reducing the lamp power supply capacity. With the goal.
[0007]
According to the present invention, in a liquid crystal projector including a plurality of projection lamps, and each projection lamp is configured to project an entire screen, any one of the projection lamps is turned on after the lighting operation of all the projection lamps. Even if the lamp is not lit, a liquid crystal projector that can continue projection with another normally lit projection lamp and perform lighting operation again for the unlit projection lamp The purpose is to provide.
[0008]
[Means for Solving the Problems]
A liquid crystal projector according to the present invention includes a plurality of projection lamps, and each projection lamp projects the entire screen. Sequential lighting means for sequentially lighting each projection lamp at predetermined time intervals so that the generated transient current does not flow simultaneously , provided for each projection lamp, and the corresponding projection lamp is in a non-lighting state. After the lighting operation for all the projection lamps is performed by the plurality of non-lighting detection means and the sequential lighting means, it is detected that any one of the non-lighting detection means has turned off the projection lamp. when the only the projection lamp that is detected as being non-lighting, that is again provided with a means for performing the lighting operation And butterflies.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 shows a lamp power supply unit and a lamp power supply control unit of a four-light type liquid crystal projector.
[0012]
The lamp power supply unit 8 includes a lamp power supply circuit 21 to 24, a lamp non-light detection circuit 31 to 34 provided for each of the four projection lamps 11 to 14, and a lamp power supply for supplying power to each of the lamp power supply circuits 21 to 24. It comprises a power supply 7.
[0013]
The lamp power control section 6 is provided for each of the lamp power circuits 21 to 24, and is used to control the switch circuits 41 to 44 for turning on the corresponding lamp power circuits 21 to 24 and to control the switch circuits 41 to 44. It comprises a timing control circuit 5.
[0014]
FIG. 2 shows a lamp lighting control method by the lamp power control unit 6 and a change in power supply current when the lamp is turned on.
[0015]
That is, at the time of lamp lighting, the timing control circuit 5 turns on the switch circuits 41 to 44 sequentially instead of simultaneously, in order to prevent overlapping of transient currents for a plurality of lamps. In this case, a transient current flows every time the power of one lamp is turned on, and after the current becomes stable, the next lamp is turned on. This operation is repeated four times, and the operation of turning on the lamp power is normally ended.
[0016]
Therefore, when the three lamps are sequentially turned on and in the steady-on state, the current flowing when the lamps are turned on becomes maximum when the fourth lamp is turned on and a transient current flows. The dashed line in FIG. 2 indicates the maximum current flowing when the four lamps 11 to 14 are simultaneously turned on without using the present invention.
[0017]
FIG. 3 shows a lamp lighting control processing procedure by the lamp power control unit 6.
[0018]
After the initial setting (step 1), the power supply circuit 21 of the first projection lamp 11 is turned on (step 2). Then, after waiting for a sufficient time for the transient current to stabilize, for example, 500 ms (step 3), the power supply circuit 22 of the second projection lamp 12 is turned on (step 4).
[0019]
After waiting for 500 ms (step 5), the power supply circuit 23 of the third projection lamp 13 is turned on (step 6). After waiting for 500 ms (step 7), the power supply circuit 24 of the fourth projection lamp 14 is turned on (step 8).
[0020]
After waiting for 500 ms (step 9), it is monitored whether or not any of the lamp non-lighting detection circuits 31 to 34 has detected lamp non-lighting (step 10).
[0021]
If the lamp non-lighting is detected by any of the lamp non-lighting detection circuits 31 to 34, the power supply circuit of the non-lighted one projection lamp is turned on. (Step 11). Then, after waiting for 500 ms (step 12), the process returns to step 10.
[0022]
Even after all of the projection lamps 11 to 14 have been turned on, it is monitored whether or not any of the lamp non-lighting detection circuits 31 to 34 has detected lamp non-lighting (step 10). If the lighting is detected, the processing of steps 11 and 12 is performed.
[0023]
In the above embodiment, in the four-lamp type liquid crystal projector, the lamp power supply unit 8 may have a capacity obtained by adding a steady-state current of three lamps and a transient current at the time of lighting of one lamp. . Further, even if lamp non-lighting occurs during the steady operation, the non-lighting lamp re-lighting process can be performed while continuing projection with the remaining projection lamps.
[0024]
【The invention's effect】
According to the present invention, in a liquid crystal projector having a plurality of projection lamps, the lamp power supply capacity can be reduced.
[0025]
Further, according to the present invention, even if one of the projection lamps is not lit after the lighting operation of all the projection lamps, the projection is continued by the other normally lit projection lamps, and The lighting operation can be performed again for the projection lamp.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a lamp power supply unit and a lamp power supply control unit of a four-lamp type liquid crystal projector.
FIG. 2 is a time chart showing a lamp lighting control method by a lamp power control unit 6 and a change in power supply current when the lamp is turned on.
FIG. 3 is a flowchart showing a lamp lighting control processing procedure performed by a lamp power control unit 6;
[Explanation of symbols]
Reference Signs List 5 timing control circuit 6 lamp power control section 8 lamp power section 7 lamp power supply 11 to 14 projection lamp 21 to 24 lamp power circuit 31 to 34 lamp non-lighting detection circuit 41 to 44 switch circuit

Claims (1)

In a liquid crystal projector comprising a plurality of projection lamps, and each projection lamp is configured to project the entire screen,
At the time of lamp lighting, a sequential lighting means for sequentially lighting each projection lamp at predetermined time intervals so that a transient current generated at the time of lighting each projection lamp does not flow simultaneously ;
A plurality of non-lighting detection means provided for each projection lamp, and detecting that the corresponding projection lamp is in a non-lighting state, and
After the lighting operation for all the projection lamps is performed by the sequential lighting unit, when any of the non-lighting detection units detects that the projection lamp is not lit, the projection that is detected to be unlit is performed. Means for performing the lighting operation again only for the
A liquid crystal projector comprising:

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