JPH0356986A - Large video display device - Google Patents

Abstract

PURPOSE:To highly efficiently use a lamp regardless of change in ambient temperature by attaching a temperature sensor to a circuit board, monitoring the temperature of a fluorescent lamp and controlling the driving of a cooling fan. CONSTITUTION:The circuit board 4 is formed of a material high in heat conductivity, and a transistor 7 is disposed in a belt-shape on a center part and the temperature sensor 8 such as a thermistor is fixed in edge parts thereof. The circuit board 4 is assembled into a display unit 1. When the fluorescent lamp 3 is turned on and a fan 6 is driven, the temperature of a heating part, where the transistor 7 is disposed, and an non-heating part becomes almost the same in the circuit board 4, and the temperature of the fluorescent lamp 3 can be monitored by the temperature sensor 8 provided on the circuit board 4. Then, the rotational speed of the fan 6 is controlled so that the temperature of the temperature sensor 8 is maintained at a fixed prescribed temperature, or the fan 6 is on/off controlled. Thus, the display unit 1 can be operated with the lamp lighting highly efficiently even when the ambient temperature is low.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to a large-sized video display device using a fluorescent lamp as a display element, and particularly to a circuit board for driving the same. [Prior Art] FIG. 4 shows a display unit constituting a large-sized video display as shown in FIG.
More powerful than 6 fluorescent lamps. Incidentally, the fluorescent lamp 3 is a fluorescent lamp for a display element that can form one pixel by itself. FIG. 6 is an exploded perspective view of the display unit 1, showing a lighting circuit glass substrate 4 for lighting the fluorescent lamp 3.
is installed in the display unit 1 corresponding to the display module 2, and a fluorescent lamp lighting circuit element (not shown) and a lamp cooling fan 6 are attached to the back plate 5 of the display unit 1. ．． (Problems to be Solved by the Invention) In the conventional example, the fan 6 is constantly driven to prevent temperature damage to circuit elements, especially transistors, due to self-heating. However, when the ambient temperature is low, The fluorescent lamp 3 will be operated in region A of the temperature characteristics shown in FIG. 7, and will operate in a state with poor lamp efficiency.

In order to operate in the B Sff region with the same characteristics, the air volume of the fan 6 can be reduced, but if the air volume is reduced, the temperature will rise due to self-heating of the transistor, causing damage to the transistor. Another method could be to monitor the temperature of the fluorescent lamps 3 and control the air volume of the fan 6. However, in this method, all the fluorescent lamps 3 that make up the display screen, that is, tens of thousands of fluorescent lamps, The number of temperature sensors corresponding to 4 is required, which increases the cost. Also,
If a temperature sensor is attached to the fluorescent lamp 3, a new sensor must be attached every time the lamp is replaced, which also increases the cost.

Another method is to provide a temperature monitor on the circuit board 4, which hardly requires replacement, but in this method, as mentioned above, if the circuit board 4 is a glass substrate, etc., the temperature on the board may be uneven. Therefore, there was a problem in that the temperature of a part of the temperature sensor on the board could not be correlated with the lamp temperature, and it did not function as a temperature monitor.

The present invention has been made to solve the above-mentioned problems, and its purpose is to be able to operate a display unit with high lamp efficiency even when the ambient temperature is low, and to An object of the present invention is to provide a large-sized video display device that is free from temperature damage due to self-heating.

(Means for Solving Problem I) In order to solve the above problems, the present invention has a plurality of fluorescent lamps attached to the front, a circuit board for lighting the fluorescent lamps is housed inside, and a cooling In a large video display device in which a display screen is constructed by arranging a plurality of display units each having a fan attached thereto, the circuit board is formed of a material with good thermal conductivity, and each circuit board is made of a material with good thermal conductivity. Install the temperature sensor,
Monitoring the temperature of the fluorescent lamp by the temperature sensor,
The cooling fan is characterized in that the drive of the cooling fan is controlled. [Embodiment] FIG. 1 shows an embodiment of the circuit board used in the present invention. The circuit board Fi4 is made of a material with good thermal conductivity, for example, aluminum. Transistors 7 are arranged in a strip shape. Further, a temperature sensor 8 such as a thermistor is attached to the end of the substrate 4. Furthermore, a lighting circuit element (not shown) is also attached to the substrate 4.

When the circuit board 4 having such a structure is incorporated into the display unit +-1 having the same structure as the display unit 1 shown in the conventional example, the fluorescent lamp 3 is turned on, and the fan 6 is driven, the temperature distribution on the circuit board 4 is as follows. As shown in FIG. 2 (al).

Here, the numbers in the figure indicate the temperature difference (in degrees Celsius) when the temperature of the temperature sensor 8 is used as a reference. In addition, the second
Figure (b) shows a comparative example using a glass substrate. As is clear from this result, in the circuit board 4 according to the present example, the temperatures of the heat generating part where the transistor 7 is disposed and the non-heat generating part are approximately the same. Furthermore, it has been confirmed that the difference between the temperature of the fluorescent lamp 3 and the temperature on the circuit board 4 remains approximately constant even when the ambient temperature changes. Thereby, the temperature of the fluorescent lamp 3 can be monitored by the temperature sensor 8 provided on the circuit board 4. Therefore, temperature sensor 8
The rotation speed of the fan 6 is controlled or the drive of the fan 6 is turned on or off so that the temperature of the fan 6 is kept constant at a predetermined temperature.
By performing the off control, the display unit 1 can be operated with high lamp efficiency even when the ambient temperature is low.

FIG. 3 is a graph showing the relationship between the temperature of the temperature sensor 8 and the lamp brightness when the drive of the fan 6 is controlled on and off. Because of this, the thermal time constant is smaller than that of the fluorescent lamp 3, and it is rapidly cooled down. On the other hand, since the fluorescent lamp 3 has a larger thermal time constant than the circuit board 4, the temperature decreases more slowly, and therefore a substantially constant brightness is maintained. [Effects of the Invention] As described above, the present invention forms a circuit board that is rarely replaced with a material with good thermal conductivity, and also attaches a temperature sensor to the circuit board, and monitors the temperature of a fluorescent lamp using the temperature sensor. However, by controlling the driving of the cooling fan, the temperature on the circuit board becomes approximately uniform, and
Since it can also be correlated with the lamp temperature, the temperature of the fluorescent lamp can be alternatively monitored on a circuit board that is replaced less frequently. As a result, the lamp temperature can be maintained at approximately the optimum temperature, allowing the lamp to be used efficiently despite changes in ambient temperature.In addition, the temperature sensor is attached to the circuit board, which is replaced less frequently. , the cost can be significantly reduced compared to the case where each fluorescent lamp is provided. Furthermore, the heat dissipation properties of the circuit board are good, so the temperature on the board can be made uniform, and even when the entire screen is fully lit or only a part of the screen is fully lit, the temperature rise of the circuit elements can be prevented. It can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the circuit board used in the present invention, and FIG. 2 is a diagram showing the temperature distribution on the circuit board, where (al is according to this embodiment and w) is according to the conventional example. Fig. 3 is a graph showing the relationship between the temperature of the temperature sensor and the lamp brightness when the fan drive is controlled on and off, Fig. 4 is a perspective view of the display unit, and Fig. 5 is a large-sized image. FIG. 6 is a perspective view of the display device, FIG. 6 is an exploded perspective view of the display unit, and FIG. 7 is a graph showing the relationship between ambient temperature and relative brightness.

Claims (1)

[Claims] (1) Display by arranging multiple display units vertically and horizontally with multiple fluorescent lamps attached to the front, a circuit board for lighting the fluorescent lamps housed inside, and a cooling fan attached to the rear. In a large video display device comprising a screen, the circuit board is formed of a material with good thermal conductivity, a temperature sensor is attached to each circuit board, the temperature of the fluorescent lamp is monitored by the temperature sensor, and the temperature of the fluorescent lamp is monitored by the temperature sensor. A large video display device characterized by controlling the drive of a cooling fan.