JP2762592B2 - Large image display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-sized video display device using a fluorescent lamp as a display element, and more 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.
Display modules 2, and the display modules 2
It consists of 16 fluorescent lamps 3. The fluorescent lamp 3 is a fluorescent lamp for a display element which can constitute one pixel by itself.

FIG. 6 is an exploded perspective view of the display unit 1 and a lighting circuit glass substrate 4 for lighting the fluorescent lamp 3.
Is mounted 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 mounted on the back plate 5 of the display unit 1. .

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional example, the fan 6 is always driven to prevent temperature damage due to self-heating of circuit elements, especially transistors, but when the ambient temperature is low,
The fluorescent lamp 3 is operated in the region A of the temperature characteristic shown in FIG. 7, and the operation is performed in a state where the lamp efficiency is low.

To operate in the region B having the same characteristics, the air flow of the fan 6 may be reduced. However, if the air flow is reduced, the temperature rises due to the self-heating of the transistor, and the transistor is damaged.

As another method, a method of monitoring the temperature of the fluorescent lamps 3 and controlling the air volume of the fan 6 can be considered. In this method, all the fluorescent lamps 3 constituting the display screen, that is, tens of thousands of fluorescent lamps 4 are used. It requires as many temperature sensors as the number of sensors, which is costly. When a temperature sensor is attached to the fluorescent lamp 3, a new sensor must be attached every time the lamp is replaced.
This also causes a cost increase.

As another method, the circuit board 4 that requires almost no replacement is used.
Although a method of providing a temperature monitor on the top is also conceivable, in such a method, as described above, since the temperature on the substrate is not uniform when the circuit substrate 4 is a glass substrate or the like, the correlation between the temperature sensor temperature on the substrate and the lamp temperature is determined. There was a problem that it could not be taken and did not function as a temperature monitor.

The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to operate a display unit with a high lamp efficiency even when the ambient temperature is low, and to further provide a circuit element. It is an object of the present invention to provide a large-sized image display device free from thermal damage due to self-heating.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention has a plurality of display units in which a plurality of fluorescent lamps are mounted on a front surface, a circuit board for lighting the fluorescent lamps is housed inside, and a cooling fan is mounted on a rear surface. Are arranged vertically and horizontally to form a display screen, the circuit board is formed of a material having good thermal conductivity, and a temperature sensor is attached to each circuit board, and the fluorescent lamp is operated by the temperature sensor. , And controlling the driving of the cooling fan.

〔Example〕

FIG. 1 shows an embodiment of a circuit board used in the present invention. The circuit board 4 is formed of a material having good heat conductivity, for example, aluminum, and a transistor 7 is formed in a band shape at the center of the board 4. It is arranged. A temperature sensor 8 such as a thermistor is attached to an end of the substrate 4. Further, a lighting circuit element (not shown) is attached to the substrate 4.

When the circuit board 4 having such a configuration is incorporated into the display unit 1 having the same configuration 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 becomes as shown in FIG. As shown in a).
Here, the numbers in the figure are indicated by the temperature difference (Celsius) based on the temperature of the temperature sensor 8. The second
FIG. 2B shows a comparative example, in which a glass substrate is used.

As is apparent from the result, in the circuit board 4 according to the present embodiment, the temperature of the heat generating portion where the transistor 7 is disposed and the temperature of the non-heat generating portion are substantially the same. In addition, it has been confirmed that the relationship between the temperature of the fluorescent lamp 3 and the temperature on the circuit board 4 is substantially constant even when the ambient temperature changes. Thus, the temperature of the fluorescent lamp 3 can be monitored by the temperature sensor 8 provided on the circuit board 4. Therefore, by controlling the rotation speed of the fan 6 or controlling the driving of the fan 6 so that the temperature of the temperature sensor 8 is kept constant at a predetermined temperature, the lamp is controlled even when the ambient temperature is low. The display unit 1 can be operated with high efficiency.

FIG. 3 is a graph showing the relationship between the temperature of the temperature sensor 8 and the lamp brightness when the driving of the fan 6 is controlled to be turned on and off. As a result, the thermal time constant is smaller than that of the fluorescent lamp 3, and the lamp is rapidly cooled. On the other hand, since the fluorescent lamp 3 has a larger thermal time constant than the circuit board 4, the temperature decreases slowly, and therefore, a substantially constant luminance is maintained.

〔The invention's effect〕

As described above, the present invention forms a circuit board with a low frequency of replacement with a material having good thermal conductivity, attaches a temperature sensor to the circuit board, monitors the temperature of the fluorescent lamp with the temperature sensor, , The temperature on the circuit board becomes substantially uniform, and the correlation with the lamp temperature is obtained, so that the temperature of the fluorescent lamp can be monitored alternately on the circuit board with less frequent replacement. As a result, the lamp temperature can be substantially maintained at the optimum temperature, and the lamp can be used in an efficient state despite changes in the ambient temperature. Also, since the temperature sensor is attached to the circuit board that is not frequently replaced,
Significant cost reduction can be achieved as compared with the case where each fluorescent lamp is provided. Furthermore, since the circuit board has good heat dissipation, the temperature on the board can be made uniform, and the temperature rise of the circuit elements can be reduced even in various displays, that is, when the entire screen is fully lit or when only a part of the screen is fully lit. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a circuit board used in the present invention, and FIG. 2 is a view showing a temperature distribution on the circuit board. FIG. 3 is a graph showing the relationship between the temperature of the temperature sensor and the luminance of the lamp when the driving of the fan is on / off controlled, FIG. 4 is a perspective view of the display unit, and FIG. 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 the ambient temperature and the relative luminance. Reference Signs List 1 display unit, 2 display module, 3 fluorescent lamp, 4 circuit board, 5 back plate, 6 cooling fan, 7
... transistors, 8 ... temperature sensors.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Noriyuki Taguchi, Inventor 1048, Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-60-205572 (JP, A) JP-A-64-26885 (JP, A) Japanese Utility Model 63-94480 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G09F 9/313 G09F 9/00 304

Claims (1)

(57) [Claims] 1. A plurality of display units having a plurality of fluorescent lamps mounted on a front surface, a circuit board for lighting the fluorescent lamps housed therein, and a cooling fan mounted on a rear surface are arranged vertically and horizontally. In a large-sized video display device comprising a display screen, the circuit boards are formed of a material having good thermal conductivity, and a temperature sensor is attached to each circuit board, and the temperature sensor monitors the temperature of the fluorescent lamp. A large-sized video display device, wherein the driving of the cooling fan is controlled.