JP2570149Y2 - Luminance control circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adjusting circuit for adjusting the light emission of a light-emitting element such as a fluorescent display tube or a light-emitting diode by making the luminance of a specific light-emitting element different from others.

[0002]

2. Description of the Related Art FIG. 4 shows a case where a conventional example of the present invention is applied to a vehicle. In the figure, reference numeral 1 denotes a fluorescent display tube as a display body, which is composed of a plurality of segments. Since this fluorescent display tube is used for fuel level display, the segment 11 indicating the high fuel region is set to blue, and the segment 12 indicating the low fuel region is set to red. Reference numeral 2 denotes a control circuit for driving the fluorescent display tube 1. 3 corresponds to a pulse signal described later
Circuit for adjusting the voltage applied to the fluorescent display tube 1
You. 4 is the duty of the pulse signal by adjusting the volume etc.
It is a pulse generator that can change the ratio. Reference numeral 5 denotes a switching circuit, which is a switching circuit that controls which segment should be applied with an applied voltage depending on the amount of fuel. Therefore, the segment specified by the switching circuit 4 is
Light is emitted at a brightness based on the duty ratio determined by the pulse generator 4.

[0003]

The fluorescent display tube has the characteristic that, if the emission color is different, the luminance is different even if the same level voltage is applied. For example, it is known that the luminance of red is lower than that of blue under the same applied voltage. Therefore, in the case of this embodiment, the brightness of the red segment 12 indicating the small area of the fuel is lower than that of the blue segment 11 indicating the multi-area, resulting in an unbalanced display. This can be confirmed from the fact that when the duty ratio of the pulse generator 4 is gradually reduced, the red segment 12 becomes darker than the blue segment 11. As a countermeasure, there is a method of newly providing a control circuit for applying a high voltage only to the red segment 12.
There is a method of using a larger DC converter and an external circuit, and there is a method of using an additional circuit for increasing the duty ratio for the red segment 12, but in any case, these measures are sufficient in terms of circuit space and cost. I can't say. It should be noted that the light emitting diode also has the same problem that green becomes darker under the same applied voltage than red.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plurality of luminous bodies and each of the luminous bodies.
By changing the duty ratio of the applied voltage,
A dimming circuit for adjusting the applied voltage of the
A power of a predetermined duty ratio is applied to each of the light emitters in accordance with a force signal.
A control circuit for applying pressure, wherein the control circuit or
The light-emitting body is provided at one of predetermined outputs of the dimming circuit.
By increasing the voltage application time to at least one
Integrator circuit that makes one light emitter emit brighter than other light emitters
This is a luminance adjusting circuit for a luminous body comprising:

[0005]

An integrating circuit is connected to a specific segment so that a higher voltage can be applied than other display portions. This integration circuit integrates the pulse output under duty control,
Outputs a high effective value voltage.

[0006]

1 to 3 show an embodiment of the present invention. The same reference numerals are given to the same portions or those having the same functions as those in the conventional example, and the detailed description thereof will be omitted. FIG. 1 shows a first embodiment of the present invention. The fluorescent display tube 1 used for indicating the fuel level is composed of segments 11 and 12 which emit blue and red light. The control circuit 2 applies an applied voltage output according to an output signal of the dimming circuit 3 to a segment specified by the switching circuit 5.

By the way, an integration circuit 6 is connected to the output of the control circuit 2 for controlling the red segment 12 in each segment. The integration circuit 6 charges and discharges the applied voltage output from the control circuit 2 by means of a resistor and a capacitor. When a square wave pulse passes through the integration circuit 6, the falling edge as shown in FIG. It becomes something. That is, when the capacitor is charged, it is instantaneously charged by turning on the transistor of the control circuit 2 and when it is discharged, the fall is caused by the time constant consisting of the element and the resistance of the phosphor of the fluorescent display tube 1. It becomes smooth. Therefore, the effective value becomes higher, and light is emitted longer than the segment 11 to which the integrating circuit 6 is not connected.

That is, a small area of fuel is displayed in red.
A high effective voltage can be applied only to the segment 12 whose luminance is lower than that of blue in a multi-region to increase the luminance (brightly emit light), to provide a well-balanced display, and to provide an integrating circuit. No. 6 needs only to be connected to the segment 12 whose brightness is to be increased, and therefore does not require much circuit space and is low in cost.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, the fluorescent display tube 1 is applied to a bar graph indicating the engine speed. Each segment of the bar graph emits blue light. As the engine speed increases, the switching circuit 5 outputs a signal to emit light from the lower segment in FIG. Further, in this embodiment, in order to increase the brightness of the segment 11 'of the idling area of the engine more than the other segments 11, the dimming circuit 3 corresponding to this segment 11' is integrated.
Circuit is connected. That is, the integrating circuit 6 is connected to the connection line of the pulse generator 4 of the dimming circuit 3 corresponding to the segment 11 ' , and the segment 11' is added to the charge and discharge of the pulse signal.
The light emission time is increased to increase the luminance.
The diode is an element for preventing the light emission time of the other segments 11 from being affected by the integration circuit 6.

That is, among the segments that emit the same color, the signal for turning on and off the voltage applied to the segment 11 'whose brightness is to be increased in particular is adjusted to adjust the segment 1
Since the light emission time of 1 'is longer than that of other segments 11,
The effective value increases and the luminance can be increased.

The integrating circuit 6 is provided at a location other than the above embodiment.
For example, a connection portion between the dimming circuit 3 and the control circuit 2 , that is,
It may be connected to the output line of the optical circuit 3 and only needs to apply the applied voltage for a long time. Fluorescent display tube 1
However, the present invention is not limited to this, and can be applied to any light emitting body such as a light emitting diode.

[0012]

[Effects of the Invention] The present invention increases the luminance among a plurality of luminous bodies.
Either the dimming circuit or the control circuit of the light emitter
By providing an integration circuit for increasing the application time of the applied voltage to the luminous body at a predetermined output of
The effective value of the illuminator with the circuit is increased, and compared to other illuminants.
The overall brightness can be increased.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an output voltage waveform diagram of an integration circuit.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional example of the present invention.

[Explanation of symbols]

 1 light emitter 2 control circuit 3 dimming circuit 4 pulse generator 5 switching circuit 6 integration circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A method according to claim 1 , wherein a plurality of light emitters are applied to each of said light emitters.
Change the duty ratio of the voltage to
A dimming circuit for adjusting a voltage, and an output signal of the dimming circuit
A voltage of a predetermined duty ratio is applied to each of the luminous bodies according to
The control circuit or the control circuit.
A predetermined output of one of the optical circuits is supplied to the light-emitting body.
By increasing the pressure application time, at least one light emission
Equipped with an integration circuit that makes the body emit light brighter than other light emitters
A luminance adjusting circuit for a luminous body, comprising: