JPH0631739B2 - Dimmer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light control device, and more particularly to a product including a liquid crystal device (LCD) as a display element and a light emitting body or a lamp for illuminating the liquid crystal device. On the other hand, the present invention relates to a device for dimming the light emitter or the lamp. The device according to the present invention is used for an indicator part in a vehicle audio product such as a car stereo and a car radio.

[Prior Art and Problems to be Solved by the Invention] For example, taking an in-vehicle audio device as an example, dimming control of an LCD illumination lamp in an indicator part of the device is performed based on an operation from the outside. It was performed via a dimming control circuit provided in the device. In this place, the internal control circuit performs dimming control to relatively reduce the brightness of the lamp based on the switch operation from the outside when the surroundings are dark such as at night, while the surroundings are bright during the day. In the state, based on the release of the switch operation, the dimming control is performed so as to relatively increase the brightness of the lamp.

Therefore, if the brightness of the lamp is once adjusted (reduced) at night to suppress glare and then used in the daytime, the brightness of the lamp is relatively dark due to the bright surroundings, and the LCD display is visible. There is an inconvenience that it becomes difficult, that is, the visibility is lowered. On the contrary, during the daytime, the brightness of the lamp is temporarily adjusted (increased) to improve visibility.
However, when used in that state at night, the brightness of the lamp is relatively dazzling due to the dark surroundings. To deal with such inconvenience,
It is necessary to repeat the switch operation as appropriate according to the brightness of the surroundings, but this is complicated and not preferable.

On the other hand, an indicator portion for visually displaying the vehicle speed is provided inside the vehicle, and this indicator portion is also provided with a dimming control circuit similar to the above-described audio device for exclusive use. This vehicle speed display dimming control circuit performs dimming control so as to reduce the brightness of the lamp in response to the "lighting" status signal of the headlight when the headlight is lit, such as at night, and vice versa. When the headlight is off, the dimming control is performed so as to increase the brightness of the lamp in response to the "off" state signal of the headlight. In this case, it is extremely suitable for the user if the dimming control in the audio device described above can be performed in conjunction with the vehicle speed display dimming control.

The dimming control for the vehicle-mounted device has been described above. Generally, an LCD as a display element and the LCD are described.
When there are two products provided with a lamp for illumination, it is preferable that the dimming control on one side can be performed in cooperation with the dimming control on the other side.

The present invention was created in view of the above points, and an object of the present invention is to provide a light control device capable of preventing glare and improving visibility without requiring troublesome work.

[Means for solving problems]

The problem with the above-mentioned conventional technique is that the external device has a first brightness control device that performs two-step brightness control of the lighting device and a second brightness control device that controls the brightness of the display device independently of the external brightness control device. A device for performing light control of a light-emitting body of a product in accordance with an illumination state of the device, the first terminal receiving a first brightness control signal output from the first brightness control device,
A second terminal for inputting a second brightness control signal output from the second brightness control device, and provided inside the product,
An internal control circuit that controls a voltage level applied to the light emitter based on the first brightness control signal and the second brightness control signal, and the first brightness control signal is at a first level. When the first brightness control signal is at the second level, the second brightness control signal is invalidated and a voltage of a predetermined level is applied to the light emitter, and when the first brightness control signal is at the second level, the second brightness control signal is enabled. And a voltage lower than the predetermined level and controlled according to the second brightness control signal to be applied to the light-emitting body. To be done.

[Work]

According to the above-mentioned configuration, the internal control circuit performs the two-step brightness control of the lighting device in the external device of the product to be dimmed, for example, the lighting / extinguishing control, or the two steps for performing the high brightness / low brightness illumination. According to the brightness control signal, that is, the first brightness control signal, the second brightness control signal output from the second brightness control device is set to “valid” or “invalid”.

Therefore, when the lighting device is turned on or off according to the brightness of the surroundings, the light emitting body of the product receives the dimming control by the second brightness control signal from the outside and is turned on by the voltage of a relatively low level. Alternatively, the light is turned on by a voltage of a predetermined level without being subjected to the dimming control by the second brightness control signal from the outside. That is, dimming control is performed when the surroundings are dark, and dimming control is performed when the surroundings are bright. In this case, glare can be prevented in the case of and visibility can be improved in the case of.

Details of other structural features and operations of the present invention will be described using embodiments described below with reference to the accompanying drawings.

〔Example〕

FIG. 1 is a block diagram showing the structure of a light control device as an embodiment of the present invention. The illustration of FIG. 1 shows a case where the device of the present invention is applied to an on-vehicle audio device.

In FIG. 1, reference numeral 1 denotes a configuration of an indicator part of an audio device, in which D is a liquid crystal device (LCD) as a display element, LP is a lamp for illuminating the LCD,
Reference numeral 4 denotes an internal control circuit for controlling the voltage applied to the lamp to adjust (dimming) the light quantity of the lamp. The internal control circuit 4 has a potential setting circuit 5 which will be described in detail later,
The dimming is realized by setting the voltage applied to the one end E2 side of the lamp in multiple stages by the action of this circuit, that is, in the illustrated example, either the voltage V1 or the voltage V2. The other end E1 side of the lamp LP is connected to the power supply terminal so that a predetermined positive voltage V0 is applied via the internal control circuit 4 based on the power supply input from the terminal T0. Further, T1 and T2 respectively represent control terminals, the terminal T1 is connected to the potential setting circuit 5, and the terminal T2 is connected to one end E2 side of the lamp.

The part indicated by A schematically shows how the voltage applied to the one end E2 side of the lamp is switched to either V1 or V2 by the action of the potential setting circuit 5.

Reference numeral 2 denotes an external control device, which is constituted by a vehicle speed display light control device used in an indicator portion for visually displaying the vehicle speed in this embodiment. Although this vehicle speed display light control device 2 is known, its description is omitted, but it outputs a control signal S1 having a voltage level V1 (> V2) according to the ambient brightness. This control signal S1 is applied to the above-mentioned control terminal T2. 3 indicates a headlight, and an ON / OFF signal based on lighting (ON) or extinguishing (OFF) of this headlight is S2.
The control signal S2 is applied to the control terminal T1 described above. In this embodiment, when the headlight is ON in the dark environment such as at night, the control signal of "H" level
S2 is output, and the luminous body of the indicator portion (not shown) is lit with the brightness controlled by the vehicle speed display light control device 2. In addition, when the headlight is off in a bright environment such as daytime, the control signal S2 of "L" level is output.
Is output, and the light emitter in the indicator section is turned off. That is, the brightness of the indicator portion is controlled in two stages in conjunction with ON / OFF of the headlight, and the brightness is also controlled by the vehicle speed display light control device 2.

Next, a specific configuration example of the main part of the apparatus shown in FIG. 1, that is, the internal control circuit 4 will be described with reference to the circuit diagram of FIG.

In FIG. 2, C1 to C5 represent digital transistors, of which C1, C3, C4 and C5 digital transistors are NPN transistors whose emitters are grounded,
It consists of a resistor connected between the base and emitter and an input resistor connected to the base (ROHM Co .;
DTA114). On the other hand, the digital transistor C2 is composed of a collector-grounded PNP transistor, a resistor connected between the base and the emitter, and an input resistor connected to the base (ROHM; DTA114). The digital transistor C2 is connected to the power supply terminal T0, and the voltage (13V) of the vehicle battery is applied to the terminal.

A signal based on power-on for activating the indicator unit is input to the input end P, and therefore, an “H” level signal is applied to the input end P while the display function is being executed. There is. The input terminal P is connected to the digital transistor C1 and further connected to one end of the resistor R1 and one end of the resistor R2 in the potential setting circuit 5 via the digital transistor C2. The other end of the resistor R1 is connected to the base of the NPN transistor Tr (2SC1847), the cathode of the Zener diode ZD (zener voltage; 10V), and one end of the electrolytic capacitor C, and the other end of the capacitor is grounded. This capacitor C has a breakdown voltage of 16 V and a capacitance of 220 μF, and contributes to stabilizing the potential of the cathode of the Zener diode ZD. The collector of the transistor Tr is connected to the power supply terminal T0, and the emitter is connected to one end E1 of the lamp LP.

The control terminal T1 is connected to the anode of the Zener diode ZD via the digital transistor C3, and is also connected to the other end E2 of the lamp LP via the digital transistors C4 and C5 in the potential setting circuit 5. The other end of the resistor R2 is connected to the connection point of the digital transistors C4 and C5. Further, the anode of the Zener diode ZD has two silicon diodes D1 connected in series.
And is grounded through D2 in the forward direction. Meanwhile, the second
The control terminal T2 of is connected to the other end E2 of the lamp LP through the silicon diode D3 in the reverse direction.

Next, dimming control by the apparatus of FIG. 1 will be described with reference to FIGS. 2 and 3 (a) to (f).

If it is assumed that the vehicle is running, the external control device 2, that is, the vehicle speed display light control device is functioning, so that the device outputs the control signal S1 having the voltage level V1 as described above. To be done. Then, when the power of the audio device is turned on at any time, a predetermined voltage is applied to the power supply terminal T0.
(13V) is applied, and a "H" level signal is applied to the input terminal P.

At this point, since the digital transistor C1 is in the ON state and the digital transistor C2 is also in the ON state in response to this, the Zener diode ZD has its cathode at the ON resistance and the resistor of the digital transistor C2.
A voltage of about 12V is applied in consideration of the voltage drop due to the resistance of R1. Therefore, the transistor Tr is turned on, and the voltage corresponding to the cathode potential is applied to the one end E1 of the lamp LP.

When the surroundings are dark such as at night At this time, the headlight 3 is in a lighting (ON) state, and the "H" level signal S2 is applied to the control terminal T1. Therefore,
The digital transistor C3 is turned on, and the anode of the Zener diode ZD becomes almost zero level. At this time, a voltage equal to the Zener voltage of the Zener diode ZD, that is, a voltage of 10V is applied to one end E1 of the lamp LP.

On the other hand, in response to the "H" level control signal S2, the digital transistor C4 is turned on, which turns off the digital transistor C5. Therefore, the lamp LP
To the other end E2 of the control signal of a predetermined level from the control terminal T2.
S1 is applied via diode D3 in the opposite direction. That is, the dimming control by the external control device 2 becomes “effective”.

In this state, a reduced level voltage based on the external dimming control, that is, a voltage of about (10-V1) V is applied to both ends of the lamp LP, thereby reducing the light amount of the lamp.
That is, since the illuminance of the LCD decreases according to the brightness of the surroundings, glare can be prevented.

At the time of bright surroundings such as daytime At this time, the headlight 3 is in the off state (OFF), and the signal S2 of "L" level is applied to the control terminal T1. Therefore, the digital transistor C3 is turned off, and the potential of the anode of the Zener diode ZD exhibits a voltage (about 1.4V) higher by the voltage drop of the diodes D1 and D2. At this time, a voltage of 11.4 V is applied to one end E1 of the lamp LP.

On the other hand, the digital transistor C4 is turned off in response to the "L" level control signal S2, and the digital transistor C5 is turned on. Therefore, the lamp LP
The electric potential of the other end E2 of C is clamped to almost zero level.
That is, the dimming control by the external control device 2 is “invalid”.

In this state, the maximum level voltage across the lamp LP,
That is, about 11.4 V is applied, which increases the light intensity of the lamp. That is, since the illuminance of the LCD is increased, the visibility is improved.

In the above-described embodiment, the voltage applied to the lamp LP, that is, the brightness of the lamp depends on the Zener voltage of the Zener diode ZD and the level of the control signal S1 from the external control device 2 when the headlight is ON. The headlight is off
At that time, it depends on the reverse breakdown voltage of the Zener diode ZD and the magnitude of the forward voltage drop of the two silicon diodes D1 and D2. Therefore, by appropriately selecting the Zener voltage of the Zener diode or the number of connected silicon diodes, it is possible to easily perform the appropriate dimming desired by the user, that is, the glare is prevented while the visibility is improved. Can be realized.

〔The invention's effect〕

As described above, according to the light control device of the present invention, it is possible to easily realize appropriate light control desired by the user without requiring troublesome work, prevent glare, and improve visibility. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a light control device as an embodiment of the present invention, FIG. 2 is a circuit configuration diagram of a main part of the device of FIG. 1, and FIG. 3 is a light control by the device of FIG. FIG. (Explanation of symbols) 1 ... Product (audio equipment), 2 ... External control device (vehicle speed display dimmer), 3 ... Second light emitter (headlight), 4 ... Internal control circuit (audio system) Dimmer for equipment), 5 ... Potential setting circuit, D ... Liquid crystal device (LCD), LP ... LCD lighting lamp, T0 ... Power supply terminal, T1, T2 ... Control terminal, S1, S2 ... …Control signal.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G09G 3/18 7319-5G G11B 33/12 P

Claims (1)

[Claims] 1. A first brightness control device (3) for performing two-step brightness control of a lighting device and a second brightness control device (2) for controlling the brightness of a display device independently of the brightness control device. The illuminator (L) of the product (1) is linked with the illumination state of the external device
A first terminal (T1) for inputting a first brightness control signal (S2) output from the first brightness control device; and a second brightness A second terminal (T2) for inputting a second brightness control signal (S1) output by the control device; and a second terminal (T2) provided inside the product and based on the first brightness control signal and the second brightness control signal. And an internal control circuit (4) for controlling the voltage level applied to the light emitting body, the second brightness control signal being invalidated when the first brightness control signal is at the first level. A voltage of a predetermined level is applied to the light emitter, the second brightness control signal is enabled when the first brightness control signal is at the second level, and the level is lower than the predetermined level. It is controlled to apply a voltage of a level according to the second brightness control signal to the light emitting body. A light control device characterized by controlling.