JP3344588B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and can be applied to, for example, a device mounted on an automobile.

[0002]

2. Description of the Related Art Conventionally, a display device mounted in a car has been required to be small, thin, and highly visible because of the necessity of being mounted on a dashboard or the like. For example, an LCD (liquid crystal display) with a backlight is required. Used.

[0003] In practice, as the backlight of this LCD,
For example, a cold-cathode tube (CF
L) is used so that a driver as a user can comfortably view the display on the LCD.

[0004]

However, when the CFL is used as the backlight of the LCD as described above, when the surroundings are bright during the daytime, the display on the LCD can be viewed comfortably by driving to emit light at the maximum brightness. When the night environment becomes dark, the CFL may be too bright and hinder driving.

In order to solve such a problem, the brightness of the CFL is reduced in synchronism with the lighting of a headlight or a small lamp, as in the display of a speedometer or the like of an automobile, or the CFL is adjusted by an adjustment volume. It is conceivable to change the brightness.

However, when the brightness of the CFL is synchronized with the lighting of a headlight or the like as described above, the brightness of the CFL can only be changed in two stages, and when the brightness is reduced by the driver, the brightness is too dark. There is a problem that it is difficult to see.

When the brightness of the CFL is varied by the adjustment volume, a complicated operation of adjusting the adjustment volume while watching the LCD display is required every time the surrounding brightness changes. In each case, the solution was still insufficient in terms of safe driving.

[0008] In addition to these problems, the CFL also:
For example, lighting is guaranteed by inputting a rated voltage in a normal temperature range of 0 ° C. to 50 ° C. For this reason, when the ambient temperature changes drastically as in a car, if the CFL is darkened in accordance with the ambient brightness, the CF may be reduced depending on the ambient temperature.
L may not be lit.

In practice, the condition immediately after the start of the vehicle at night or in the early morning in cold weather or the like is the above-described condition.
The FL did not light up, and was still insufficient in terms of user convenience.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and aims at solving a conventional problem at a glance and proposing a display device having a backlight which emits light in response to the surrounding environment. is there.

[0011]

According to the present invention, there is provided a display apparatus using a predetermined light emitting means as a back light, a light emitting drive means for causing the light emitting means to emit light, and a surrounding brightness. Brightness detecting means 4 for detecting the brightness, operating means 6 for adjusting the brightness of light emission of the light emitting means 2 by an external operation, and brightness detecting means 4
Control means 7 for controlling the light emission operation of the light emission means 2 by driving the light emission drive means 3 in accordance with the detection result of the light emission and the operation on the operation means 6, and the control means 7 comprises:
According to the detection result, when the surroundings are sufficiently bright, the light emission driving means 3 is driven to control the light emission operation of the light emission means 2,
In other cases, the light emission driving means 3 is driven to control the light emission operation of the light emission means 2 according to the detection result of the brightness detection means 4 and the operation on the operation means 6.

[0012]

According to the detection result of the brightness detecting means, when the surroundings are sufficiently bright, the light emitting driving means is driven to control the light emitting operation of the light emitting means. By driving the light emission driving means 3 to control the light emission operation of the light emission means 2 in accordance with the result and the operation on the operation means 6, the light emission of the light emission means can be controlled when the surroundings are not sufficiently bright. The brightness can be adjusted to a brightness according to the user's preference.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

In FIG. 1, reference numeral 1 denotes a CFL driving device used for backlighting a vehicle-mounted LCD according to the present invention;
It comprises an inverter circuit 3 as a high voltage generator for generating a driving voltage for the CFL 2 from a vehicle-mounted power supply consisting of the CFL 2 and DC 12 [V].

In this embodiment, the inverter circuit 3 has a phototransistor configuration, for example, a photosensor 4 for detecting the brightness around the front window, and a positive temperature coefficient thermistor for detecting the temperature inside the vehicle and, for example, turning on when the temperature falls below freezing. And a variable resistor 6 for adjusting the brightness of the CFL 2.

Thus, the inverter circuit 3 controls the driving voltage according to the brightness around the front window detected by the photo sensor 4, the temperature inside the vehicle detected by the temperature switch 5, and the resistance value of the variable resistor 6 set by the user. CF
The brightness of L2 can be adjusted.

That is, the inverter circuit 3 is, for example, TL4
The circuit comprises an inverter PWM (plus width modulation) circuit 7, which is an integrated circuit having a DIP 16-pin configuration such as 94, an NPN-type switching transistor Q1, PNP-type drive transistors Q2 and Q3, and an output transformer 8.

Actually, the PWM circuit 7 compares the internally generated sawtooth signal with the threshold voltage VSH supplied to the fourth pin, and compares the sawtooth signal with the threshold voltage VSH which is higher than the threshold voltage VSH. A switching pulse SPWM of a duty which rises during this period is generated, which is output from the 8th and 11th pins of the PWM circuit 7 and supplied to the base of the switching transistor Q1 via the resistor R1.

The emitter of this transistor Q1 is DC
An onboard power supply + V of 12 [V] is input, and this onboard power supply + V is input to the base of the transistor Q1 via the resistor R2.

In addition, the vehicle power supply + V is supplied as drive power to the twelfth pin of the PWM circuit 7, and the first, seventh, ninth, tenth, thirteenth, and sixteenth pins are provided as drive power. Is connected to the ground line GND and grounded, and the fifth and sixth pins are connected to the ground line GND via a capacitor C1 and a resistor R3 which are external constants, respectively, and are grounded.

Further, the second pin, the 14th pin and the 15th pin of the PWM circuit 7 are commonly connected, and the second pin is connected to a resistor R4.
Through to the 4th pin. Also, the PWM circuit 7
The fourth pin is connected to a photo sensor 4, a thermistor 5, and a variable resistor 6, respectively.

The collector of the transistor Q1 is connected to a reverse diode D having one end connected to the ground line GND.
1 and the coil L1 are supplied to the center tap of the first primary winding L10 of the transformer 8, and the emitter is connected to the ground line G through resistors R5 and R6, respectively.
Drive transistors Q2, Q connected to ND and grounded
3 bases.

A resonance circuit having a first primary winding L10 and a capacitor C2 connected in parallel is connected between the collectors of the transistors Q2 and Q3.
And Q3 are connected to both ends of the second primary winding L11.

As a result, the secondary winding L12 of the transformer 8 outputs D from the secondary winding L12 in accordance with the switching operation of the transistor Q1.
From the onboard power supply + V of C12 [V], for example, AC1200
A driving voltage VC having a high voltage of [V] is output and supplied to the CFL2 through the capacitor C3. As a result, the CFL2 is turned on.

Here, in the case of the CFL driving device 1 of this embodiment, the threshold voltage VSH supplied to the fourth pin of the PWM circuit 7 is controlled by the photo sensor 4, the temperature sensor 5, and the variable resistor 6. I have.

The photo sensor 4 detects the brightness around the arranged front window, and when it becomes bright, the threshold voltage VSH becomes low. As a result, the driving voltage VC increases, and the CFL 2 is lighted more brightly.

Conversely, when the brightness around the front window becomes dark, the threshold voltage VSH becomes high, and the switching pulse S sent from the PWM circuit 7 is sent.
The rising pulse width of the PWM is narrowed, and as a result, CFL2 is lit dark. Actually, as described above, the illuminance indicating the brightness around the front window and the lighting illuminance of the CFL 2 have a substantially proportional relationship.

When the periphery of the front window is sufficiently bright, the resistance value of the variable resistor 6 can be neglected because the photo sensor 4 is in a conductive state. On the other hand, when the periphery of the front window is dark, the resistance of the variable resistor 6 is small. The threshold voltage VSH changes depending on the value. As a result, if the user controls the variable resistor 6 as desired, the lighting illuminance of the CFL 2 can be adjusted.

When the surroundings of the front window are dark and the temperature inside the vehicle is lower than the normal temperature (for example, between 0 ° C. and 50 ° C.) at which lighting is guaranteed by the rated voltage input of the CFL 2, the temperature switch 5 is turned on. . As a result, the threshold voltage VSH becomes the lowest value of 0 [V], and accordingly, the driving voltage VC has the highest value. As a result, CFL2 is easily turned on.

Further, the temperature switch 5 is turned off when the temperature inside the vehicle rises to the normal temperature. As a result, the lighting illuminance of the CFL 2 becomes the photo sensor 4 and the variable resistor 6 in the same manner as described above.
Is controlled by

According to the above configuration, the brightness around the front window is detected by the photo sensor 4, and the lighting illuminance of the CFL 2 is controlled by controlling the inverter circuit 3 according to the detection result. The CFL 2 can emit light in response to the brightness of the surroundings of the front window, and thus an LCD having a backlight suitable for use in a vehicle can be realized.

Further, according to the above-mentioned configuration, when the lighting illuminance of the CFL 2 is dark in response to the brightness around the front window, the lighting illuminance can be controlled by operating the variable resistor. Can be selected according to the above, and thus the usability of the user can be further improved.

In the above embodiment, the case where the photo sensor is arranged around the front window and the brightness of the backlight is controlled in response to the brightness around the front window has been described. However, the arrangement of the photo sensor is not limited to this. However, the present invention is not limited to this. For example, it may be arranged around the dashboard in the vehicle or at another position.

In the above-described embodiment, the case where the present invention is applied to a display device comprising an in-vehicle LCD has been described. However, the present invention is not limited to this. For example, a display device of a personal computer, etc. The present invention is suitable for being widely applied to various display devices having illumination.

[0035]

As described above, according to the present invention, in a display device using predetermined light emitting means as back lighting, a light emission driving means for causing the light emitting means to emit light, and a brightness detecting means for detecting ambient brightness. Operating means for adjusting the brightness of light emission of the light emitting means by an external operation, and driving the light emitting driving means in accordance with the detection result of the brightness detecting means and the operation on the operating means. Control means for controlling the light emission operation, wherein the control means controls the light emission operation of the light emission means by driving the light emission drive means when the surroundings are sufficiently bright, according to the detection result of the brightness detection means, In the case of, the light emission driving means is driven in accordance with the detection result of the brightness detection means and the operation on the operation means to control the light emission operation of the light emission means, so that when the surroundings are not sufficiently bright Occasionally, it is possible to adjust the brightness in accordance with the user's preference the brightness of light emission of the light emitting means,
Thus, a display device that can significantly improve the user's convenience can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a CFL driving device according to one embodiment of a display device according to the present invention.

FIG. 2 is a connection diagram illustrating a circuit configuration of a CFL driving device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CFL drive device, 2 ... CFL, 3 ... Inverter circuit, 4 ... Photo sensor, 5 ... Temperature switch, 6
... variable resistor, 7 ... PWM circuit for inverter, 8 ...
Transformer, Q1, switching transistor, Q2,
Q3: A driving transistor.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-309316 (JP, A) JP-A-1-179129 (JP, A) JP-A-63-187188 (JP, U) JP-A-2-187188 81524 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 35/00-37/06 G02F 1/133 535 G09F 9/00 337 G09G 3/36

Claims (3)

(57) [Claims] 1. A table using a predetermined light emitting means as a backlight.
A light emission driving means for causing the light emission means to emit light, a brightness detection means for detecting ambient brightness, and an external operation for controlling the brightness of the light emission of the light emission means.
Operating means for adjusting the brightness, and the detection result of the brightness detecting meansas well asFor the above operation means
In response to the operation, the light emission driving unit is driven to
Control means for controlling the light emitting operation of the light emitting means,The control means includes: The surroundings are filled according to the detection result of the brightness detecting means.
When the light is bright enough, the light emission drive means is driven to
Controls the light emission operation of the light means, otherwise,
The detection result of the rust detection means and the
In response to an operation, the light emission driving unit is driven to drive the light emission
Control the light emission operation of the step A display device characterized by the above-mentioned. 2. The apparatus according to claim 1, further comprising a temperature detecting means for detecting the temperature of the surroundings, wherein said controlling means is provided when the surroundings are not bright enough .
When the temperature detecting unit detects that the ambient temperature is lower than a predetermined temperature, the light emitting driving unit is driven to facilitate lighting of the light emitting unit, and the light emitting operation of the light emitting unit is performed. 2. The method according to claim 1, wherein the control is performed.
The display device according to claim 1. 3. The display device according to claim 2, wherein the predetermined temperature is a temperature at which lighting of the light emitting unit is guaranteed when a rated power of the light emitting unit is input.