JPH0365986A - lighting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lighting device for illuminating a liquid crystal display used to display the functions and operations of audio/video equipment (hereinafter abbreviated as AV equipment). .

Conventional technology Liquid crystals used in liquid crystal displays do not emit light by themselves, but when electricity is applied to the element, the crystal structure changes and the light refractive index changes, so it reflects other light and emit light by itself. It appears to emit light, and is difficult to see when the surrounding area is dark. In order to compensate for this drawback, in order to make it possible to check the display contents even in dark places by illuminating the liquid crystal display as in the past, we have developed a system that illuminates only when the device is turned on, a system that illuminates only when the device is powered on, and a system that illuminates only when the device is powered on. Some lights are turned on only when the switch is turned on, while others have a clock function and are lit all the time.

Problems to be Solved by the Invention However, with the above conventional configuration, since most devices such as recent AV devices are equipped with a clock function, the above lighting method only works when the power is ON. The lighting method makes it difficult to see the clock display when the power is off.
Further, in the method of constantly lighting the lamp, there is a problem in that the battery life is shortened when the lamp is powered by a battery. Another problem is that the lighting may be too bright when the room is dark, such as at night. The present invention solves the above-mentioned conventional problems, and when the above-mentioned AV equipment is driven by AC power, it is brightly illuminated when the equipment is powered on, and illuminated when the equipment is powered off.
In this case, the lighting should be slightly dimmed so that the brightness is moderate even when the room is dark such as at night, and if the device is powered by batteries, the lighting should be bright when the device is turned on, and the lighting should be bright when the device is turned off. In this case, the purpose is to turn off the light to avoid battery consumption and extend battery life.

Means for Solving the Problems In order to solve the above problems, the lighting device of the present invention includes a circuit that determines and switches whether the AV equipment is driven by AC power or battery power, and a circuit that determines whether the AV equipment is driven by AC power or battery power. Depending on the ON/OFF status of the device's power, the brightness of the light generated by the lighting device can be changed to "bright" or "dark".

The brightness of the lighting device is set to "bright/dark" according to the ON/FF of the equipment when using AC power, and when using batteries, the circuit controls the brightness of the lighting device in three stages: "lights off". ON/○
The brightness of the lighting device is controlled as "bright/off" according to the FF.

Effect of the Invention With the above-described configuration, the present invention adjusts the brightness so that when the AV equipment is driven by AC power, the liquid crystal display is brightly illuminated when the equipment is powered on, and illuminated slightly dimly when the equipment is powered off. is controlled, and the appropriate brightness is set even when the room is dark such as at night, and the device is turned on when using batteries.
In the case of
When in FF mode, the lighting device is turned off to extend the life of the battery.

Embodiment Hereinafter, a lighting device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a lighting device according to an embodiment of the present invention. In FIG. 1, 1 is a light generating section, 2 is a second stabilized power supply, 3 is a first brightness setting resistor,
4 is a second brightness setting resistor, 5 is a switching transistor, 6 and 7 are bias resistors, 8.15 is a switching diode, 9 is a first stabilized power supply, 10 is a power switch, 11 is a power supply switching section, 12 is the battery, 13 is AC/DC
A changeover switch, 14 is an AC input plug, 16 is a rectifier circuit, 17 to 24 are LED lighting, 25 is a liquid crystal display, 26
is the liquid crystal drive section.

Hereinafter, the operation of the lighting device of the present invention will be explained using the drawings.

First, a case will be described in which an AV device using the liquid crystal display 26 is driven by an AC power source. When an AC cord is inserted into the AC input plug 14 of the power supply switching section 11, the AC/DC changeover switch 13 is automatically switched to the AC side, that is, to the terminal side, and the input from the AC input plug 14 is automatically activated. The AC power source is converted into a DC power source by a rectifier circuit 16.

Here, when the power switch 10 of the AV equipment is in the ON state, a DC power source is connected to the first stabilized power source 9 via the AC/DC changeover switch 13 and the power switch 1o. The first stabilized power source 9 has an output A to the second stabilized power source 2,
It has an output B that controls the switching transistor 6,
The output A is input to the second stabilized power source 2 via the switching diode 8, and the output of the second stabilized power source 2 is connected to the anode side C of the illumination LEDs 17 to 24 of the light generating section 1. Here, the lighting LEDs 17 to 24 are LED17
~20 are connected in series in the same direction, LED21~24
are also connected in the same way. Furthermore, in order to connect these in parallel, LED17 and 21+7)7/-)', LED
The cathodes 20 and 24 are connected. Also, the lighting L
A first brightness setting resistor 3 is connected to the cathode side of the EDl 7 to 24, and a second brightness setting resistor 4 and a collector of a switching transistor 6 are connected to one terminal of the first brightness setting resistor 3. is connected. The other terminal of the second brightness setting resistor 4 and the switching transistor 5
The emitter of is connected to GND. On the other hand, the output B of the first stabilized power supply 9 is inputted to the base side of the switching transistor 6 via the bias resistors 6 and 7, and turns the switching transistor s into an ON state 71. When the switching transistor 6 is turned on, the second brightness setting resistor 4 is short-circuited.
Since the current supplied to the lighting LEDs 17 to 24 increases, the lighting LEDs 17 to 24 light up brightly. Next, to explain the case where it is driven by AC power and the power switch 10 is OFF, the second stabilized power supply 2 is used to keep the brightness of the lighting LEDs 17 to 24 constant even if the power supply voltage changes.
Power is supplied to the rectifier circuit 16 through a switching diode 15. However, the switching transistor 5 is in an OFF state because the first stabilized power supply 9 is not operating, and the brightness of the illumination LEDs 17 to 24 is the same as that of the first stabilized power supply 9.
Since the current is set by the sum of the resistance values of the brightness setting resistor 3 and the second brightness setting resistor 4, the current decreases and the brightness of the illumination LEDs 17 to 24 becomes darker than when the power switch 10 is turned on.

Next, the operation in the case of battery drive will be described. When the AC cord is removed from the AC input lug 14 of the power supply switching section 11, the AC/DC changeover switch 13 is automatically switched to the battery drive state. First, when the power switch 10 is turned on, the operation is the same as when AC is driven, and power is supplied to the first stabilized power source 9 via the A C/DC selector switch 13 and the power switch 10, and the first stabilized output A of the power supply 9,
! :B, the second stabilized power supply 2 and the switching transistor 5 are controlled to brightly light the illumination LEDs 17 to 24. Next, when power switch 1o is OFF, the second
Since there is no power supply to the stabilized power source 2, the light generating section 1 does not light up. With the above, it is automatically determined whether the AV device is powered by AC power or battery, and if it is driven by AC power, it will be bright when the AV device is turned on, and at 022 o'clock. In the case where the AV equipment is powered by a battery and the AV equipment is powered by a battery, it is possible to construct a lighting device that illuminates the AV equipment as brightly as an AC power source when the power is on, and turns off the light at 022 o'clock.

Effects of the Invention As described above, the present invention enables AV equipment that uses a liquid crystal display to indicate functions and operating states to be driven by AC power or not.
It automatically determines whether the AV equipment is powered by batteries, and if the AV equipment is powered by AC power, the LCD display will be bright (bright when the AV equipment is turned on) and slightly dimmed at 022 o'clock, and the AV equipment will be illuminated when the AV equipment is powered by batteries. When the AV equipment is powered on, it can be configured so that when it is turned on, it lights up just like an AC power source, and turns off at 022, so it is bright when it is in use, and when the AC power is on, it stays bright at night. To provide a lighting device for a liquid crystal display that maintains appropriate brightness even when the room is dark and has a longer battery life when using batteries.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a lighting device for a liquid crystal display according to an embodiment of the present invention, and Fig. 2 is a block diagram of a lighting device for a liquid crystal display according to an embodiment of the present invention.
It is a timing chart showing the brightness of a lighting device with respect to FF. DESCRIPTION OF SYMBOLS 1... Light generation part, 3... Resistor for brightness setting, 4... Resistor for brightness setting, 5... Switching transistor, 8, 15... ...Switching diode, 1009.・、・Power switch, 1
1...Power switching unit, 12...Battery, 1
3... AC/DC selector switch, 14...
...AC input plug, 16... Rectifier circuit, 17
~24...LED for lighting, 26...Liquid crystal display.

Claims (1)

[Claims] A lighting device that illuminates a liquid crystal display used to display the functions and operations of equipment from the rear, and a circuit that automatically determines and switches whether the equipment is powered by AC power or batteries. and a control circuit that controls the brightness of the light generated by the lighting device depending on the ON/OFF state of the device's power source when the device is powered by an AC power source or a battery. The lighting is bright and the lighting is slightly dimmed when the device is turned off.If the device is powered by batteries, the device is turned off.
A lighting device characterized in that it is configured to illuminate brightly in the same way as an AC power source when it is turned on, and turn off when it is turned off.