JP2002341835A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element in which practically no change is observed in the visibility even though environmental temperature is changed and convenience is improved. SOLUTION: A voltage converting section 11 converts the voltage supplied by a primary battery 10 and supplies the converted voltage to a liquid crystal display section 12. A light receiving section 15 detects light quantity, which passes a pixel 13 that is set into a state so that it passes the light beams of the section 12 among the light beams emitted from a light source section 14, so as to indirectly detects the change in environmental temperature. A control section 16 controls the section 11 in accordance with the detection result of the section 15 so as to control voltage to be supplied to the section 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monochrome or color liquid crystal display device, a liquid crystal display device having a segment electrode, a fixed pattern electrode, or a matrix electrode formed thereon.
Static drive system, passive matrix drive system,
The present invention relates to a liquid crystal display device driven by a dynamic driving method and other liquid crystal display devices.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a main part of a conventional liquid crystal display device. 4, reference numeral 100 denotes a primary battery such as a battery, and 101 denotes a primary battery 100
Is a voltage converter for converting the voltage of FIG. In general, the voltage required by the liquid crystal display unit 102 is higher than the voltage of the primary battery 100, so that the voltage converter 101 boosts the voltage supplied from the primary battery 100 to the voltage required by the liquid crystal display unit 102. Is used.

[0003] The control unit 103 outputs a display signal S100 for controlling the display content of the liquid crystal display unit 102. The display signal S100 is a signal for displaying characters and images on the liquid crystal display unit 102, and is input to the liquid crystal display unit 102. For convenience of explanation, the control unit 10 shown in FIG.
Reference numeral 3 includes a driving circuit (driver circuit) for driving the liquid crystal display unit 102.

The liquid crystal display unit 102 has, for example, a configuration having a plurality of pixels, and each pixel is in a state of not transmitting light when no voltage is applied. This pixel is in a state of transmitting light when a voltage supplied from the voltage converter 101 is applied to a correspondingly provided pixel electrode and a display signal S100 output from the control unit 103 is applied. , Characters and images corresponding to the image signal S100 are displayed.

[0005]

The liquid crystal display section 102 provided in the liquid crystal display device applies a constant voltage to the pixel electrodes to display, for example, characters.
It has the characteristic that the visibility of characters changes depending on the ambient temperature. This is due to the intrinsic properties of the liquid crystal. FIG. 5 is a diagram illustrating the relationship between the ambient temperature and the voltage applied to the liquid crystal display unit 102 when the same visibility is obtained.

As shown in FIG. 5, in order to obtain the same visibility, when the ambient temperature is low, the liquid crystal display 10
2, it is necessary to lower the voltage applied to the liquid crystal display unit 102 when the ambient temperature is high. Assuming that the voltage applied to the liquid crystal display unit 102 having such characteristics is constant without changing, characters displayed on the liquid crystal display unit 102 become thin when the ambient temperature is low, and conversely, when the ambient temperature is high, the liquid crystal display The characters displayed on the unit 102 become darker. If the ambient temperature is further increased, the entire liquid crystal display unit 103 may be displayed in black, and characters may not even be visible.

In the conventional liquid crystal display device shown in FIG. 4, a constant voltage is always supplied from the voltage conversion unit 101 to the liquid crystal display unit 102, and the liquid crystal display unit 102 responds to a change in ambient temperature.
However, when the ambient temperature is low, there is a problem that the display of characters and the like is thin and difficult to see. Also, when the ambient temperature is high,
As described above, there is a problem that even the display of characters on the liquid crystal display unit 102 cannot be recognized.
Further, when the ambient temperature is low, there is a problem that display rises slowly.

In recent years, various electronic devices such as a mobile phone, a portable computer, and a portable measuring instrument (for example, a multimeter and an oscilloscope) have been miniaturized so as to be portable and used in various environments. Opportunities are increasing. Under such circumstances, there is a demand for a liquid crystal display device that does not impair the visibility even if the ambient temperature fluctuates.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a liquid crystal display device which can improve convenience without substantially impairing visibility even when the ambient temperature changes. And

[0010]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention comprises a power supply section (10, 11) for supplying a voltage to a liquid crystal display section (12) and a power supply section (10, 11) for changing the ambient temperature. And a control unit (16) for controlling a voltage supplied to the liquid crystal display unit (12) accordingly.
According to the present invention, the voltage supplied to the liquid crystal display unit is controlled in accordance with the change in the ambient temperature, so that even if the ambient temperature changes, the visibility is hardly impaired and the convenience can be improved. it can. The liquid crystal display device according to the present invention may further include a detection unit (14, 1) that detects a change in the ambient temperature by detecting a light amount transmitted through the liquid crystal display unit (12).
5) is provided. Here, in the liquid crystal display device of the present invention, the detection unit (14, 15) includes a light source unit (1) provided on one side surface of the liquid crystal display unit (12).
4) and a light receiving unit (15) provided on the other side surface of the liquid crystal display unit (12) and receiving light emitted from the light source unit (14) and transmitted through the liquid crystal display unit (12). It is preferred to include. Further, the liquid crystal display device of the present invention,
The size of the emission section of the light source section (14) and the light receiving section (1)
It is preferable that the size of 5) is set to be substantially the same. Further, in the liquid crystal display device of the present invention, it is preferable that the light receiving section (15) is provided with a light shielding section (35) for shielding light other than the light from the light source section (14). Also,
In the liquid crystal display device according to the present invention, the detection unit (14, 15)
Is preferably disposed in the non-display area (A2) of the liquid crystal display section (12). Still further, in the liquid crystal display device according to the present invention, the liquid crystal (13) of the liquid crystal display unit (12) at a position where the detection units (14, 15) are arranged.
Are set in a light transmitting state at least when the liquid crystal display section (12) operates. According to the present invention, during operation of the liquid crystal display unit, the voltage supplied to the liquid crystal display unit is controlled according to a change in the ambient temperature. Can be faster. In the liquid crystal display device according to the present invention, the control section (16) sets the light amount at a reference ambient temperature and the voltage supplied to the liquid crystal display section (12) as a reference light amount and a reference voltage, respectively. It is characterized by being. Further, in the liquid crystal display device according to the present invention, the control unit (16) supplies a voltage supplied to the liquid crystal display unit (12) based on a comparison result between the light amount detected by the light receiving unit (15) and the reference light amount. Is controlled.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an electrical configuration of a main part of a liquid crystal display according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a primary battery such as a battery, and reference numeral 11 denotes a voltage converter for converting the voltage of the primary battery 10 into a voltage required by the liquid crystal display unit 12.

Since the voltage required by the liquid crystal display unit 12 is generally higher than the voltage of the primary battery 10, the voltage converter 11
A booster circuit for boosting a voltage supplied from the primary battery 10 to a voltage required by the liquid crystal display unit 12 is used. Here, the voltage converter 11 is configured to be able to vary the voltage supplied to the liquid crystal display unit 12 based on a control signal C1 or a control signal C2 output from the control unit 16 described later. In addition, the primary battery 10 and the voltage converter 11
A power supply unit according to the present invention.

The liquid crystal display section 16 outputs a display signal S1 for controlling display contents of the liquid crystal display section 12. The display signal S1 is a signal for displaying characters and images on the liquid crystal display unit 12, and is input to the liquid crystal display unit 12.
For convenience of explanation, the control unit 13 shown in FIG. 1 includes a driving circuit (driver circuit) for driving the liquid crystal display unit 12.

The liquid crystal display unit 12 has, for example, a configuration having a plurality of pixels, and each pixel is in a state of not transmitting light when no voltage is applied. When a voltage supplied from the voltage converter 11 is applied to a correspondingly provided pixel electrode and a display signal S1 output from the control unit 16 is applied to the pixel, the pixel transmits light. Characters and images corresponding to the image signal S1 are displayed.

In the present embodiment, the liquid crystal constant section 12 is arranged such that pixels (liquid crystal) 13 arranged in a non-display area (details will be described later) are in a state of transmitting light at least when the liquid crystal display section 12 operates. It is controlled by the display signal S1 output from the control unit 16. FIG. 2 is a diagram for explaining a display area and a non-display area of the liquid crystal display device 12. As shown in FIG. 2, the outer shape of the liquid crystal display unit 12 has a rectangular shape, and four edges of the liquid crystal display unit 12 are covered by the housing 30, and this portion is a non-display area of the liquid crystal display unit 12.

Since the display area A1 is not covered by the housing 30, the user can visually recognize the displayed content, but cannot visually recognize the content displayed in the non-display area A2. Pixel 13 is located in this non-display area A
2 is set. Returning to FIG. 1, a light source unit 14 is provided on the back surface of the liquid crystal display unit 12 and at the position of the pixel 13. The light source unit 14 constantly illuminates the pixel 13 at least when the liquid crystal display unit 12 operates. This is realized by, for example, an LED (Light Emitting Diode). During the operation of the liquid crystal display unit 12, the voltage supplied to the liquid crystal display unit is controlled according to the change in the ambient temperature. Therefore, even when the ambient temperature is low, the rise of the display can be accelerated. it can.

On the front surface of the liquid crystal display section 12, the pixels 12
Is provided with a light receiving unit 15 that receives light emitted from the light source unit 14 and transmitted through the pixels 13. The light source unit 14 and the light receiving unit 15 correspond to a detection unit according to the present invention, and detect a change in ambient temperature by detecting the amount of light transmitted through the liquid crystal display unit 12.

FIG. 3 is a perspective view showing an example of the light receiving section 15. As shown in FIG. 3, a wall 35 is formed on the light receiving surface of the light receiving unit 15, and the light receiving surface of the phototransistor 20 is arranged inside the wall 35. The wall portion 35 corresponds to a light blocking portion according to the present invention, and blocks light other than light from the light source portion 14. That is, since the liquid crystal display device of the present embodiment is mainly assumed to be provided in an electronic device carried by a user, the liquid crystal display device has a configuration shown in FIG. 3 in order to prevent the influence of ambient light such as sunlight. ing.

In the light receiving section 15 shown in FIG. 3, the opening formed by the wall 35 has a rectangular shape, and its width is W and its vertical length is H. It is preferable from the viewpoint of light use efficiency that the size of the emission part of the light source part 14 provided in a pair with the light receiving part 15 is set to be substantially the same as the size of the opening of the light receiving part 15.

The light receiving section 15 has an emitter electrode grounded,
Phototransistor 20 having a collector electrode connected to one end of limiting resistor 21, a transistor having a base electrode connected to the other end of limiting resistor 21, an emitter electrode connected to a power supply, and a collector electrode connected to one end of detecting resistor 23. 22
It is comprised including. Note that the other end of the detection resistor 23 is grounded.

When the amount of light received by the phototransistor 20 increases, the light receiving section 15 having the above-described configuration
The current flowing through increases. Since the other end of the limiting resistor 21 is connected to the gate electrode of the transistor 22, when the current flowing through the limiting resistor 21 increases, the current flowing through the transistor 22 and the detecting resistor 23 increases. Therefore, when the amount of light received by the phototransistor 20 increases, the voltage drop due to the detection resistor 23 increases.

That is, if the voltage drop of the detection resistor 23 is detected, the amount of light transmitted through the liquid crystal display unit 12 can be indirectly detected. As described above, in the present embodiment, the change in the ambient temperature is detected by detecting the amount of light transmitted through the liquid crystal display unit 12. The detection result of the light receiving unit 15 is input to the control unit 16 as a detection signal D1.

In the control unit 16, a reference light amount and a reference voltage are set in advance. Here, the reference light amount refers to the light amount transmitted through the liquid crystal display unit 12 when sufficient visibility is obtained for the content displayed in the display area of the liquid crystal display unit 12 at a reference ambient temperature (for example, 25 ° C.). (The amount of light is the amount of light indicated by the detection signal D1).
The reference voltage is a voltage applied to the liquid crystal display unit 12 at that time.

As described above, since the transmitted light amount of the liquid crystal display unit 12 is obtained indirectly by the voltage drop of the detection resistor 23, the reference light amount is set by the voltage value in the main control unit 16. I have. Hereinafter, the reference light amount is simply used as a voltage value due to a voltage drop of the detection resistor 23. The control unit 16 obtains a voltage value (this voltage is a voltage indicating a difference from the reference voltage) to be applied to the liquid crystal display unit 12 based on a difference between the light amount detected by the light receiving unit 15 and the reference light amount. The voltage supplied to the display unit 12 is controlled.

If the detection signal D1 output from the light receiving section 15 is larger than the reference light amount, the control signal C1 is output to increase the voltage applied to the liquid crystal display section 12.
Conversely, when the detection signal D1 output from the light receiving unit 15 is smaller than the reference light amount, the control signal C2 is output to lower the voltage applied to the liquid crystal display unit 12.

Next, the operation of the liquid crystal display device according to one embodiment of the present invention having the above configuration will be described. First, the voltage converter 11 converts a voltage value supplied from the primary battery 10 into a voltage required by the liquid crystal display unit 12 (here, the above-described reference voltage). The converted voltage is supplied to the liquid crystal display unit 12. Further, the control unit 16 controls the liquid crystal display unit 12.
Outputs a display signal S1 for controlling the content to be displayed. Here, the display signal S1 is also a signal for controlling the pixel 13 to always transmit light regardless of the presence or absence of display in the display area A1.

The light emitted from the light source unit 14 passes through the pixels 13 provided in the liquid crystal display unit 12, is received by the light receiving unit 15, and the amount of light is detected. In the light receiving unit 15, the light received by the phototransistor 20 is converted into a very small current corresponding to the amount of light, and the light is
2 is input to the second gate electrode. The transistor 22 amplifies the current input to the gate electrode at a predetermined amplification factor, and this current is detected by the detection resistor 13 as a voltage drop.

The voltage drop detected by the detection resistor 23 is input to the control section 16 as a detection signal D1. Control unit 16
Compares the input detection signal D1 with a preset reference light amount. If the detection signal D1 output from the light receiving unit 15 is larger than the reference light amount, the control signal C1 is output to increase the voltage applied to the liquid crystal display unit 12. Conversely, when the detection signal D1 output from the light receiving unit 15 is smaller than the reference light amount, the control signal C2 is output to lower the voltage applied to the liquid crystal display unit 12. The voltage converter 11 raises or lowers the voltage value supplied to the liquid crystal display unit 12 according to the control signal C1 or C2 output from the control unit 16.

When the ambient temperature is low, the pixel 1 of the liquid crystal display
When a large amount of light passes through 3, the display in the display area A1 becomes thin. Therefore, the value of the detection signal D1 also increases.
The control unit 16 compares the detection signal D1 with the reference light amount and outputs a control signal C1 to the voltage converter 11. At this time, since a voltage higher than the reference voltage is supplied from the voltage converter 11 to the liquid crystal display unit 12, the display in the display area A1 becomes dark. When the detection signal D1 becomes equal to the reference light amount, the control unit 16 stops outputting the control signal C1, and the voltage converter 11 stops increasing the voltage supplied to the liquid crystal display unit 12.

Conversely, when the ambient temperature is high and the amount of light transmitted through the pixels 13 of the liquid crystal display unit 12 is small, the display area A
The display of 1 becomes dark. Therefore, the value of the detection signal D1 decreases. The control unit 16 compares the detection signal D1 with the reference light amount and outputs a control signal C2 to the voltage converter 11. At this time, the voltage converter 11 switches to the liquid crystal display 12
Is supplied with a voltage lower than the reference voltage.
The display of 1 becomes thin. When the detection signal D1 becomes equal to the reference light amount, the control unit 16 stops outputting the control signal C2, and the voltage converter 11 stops decreasing the voltage supplied to the liquid crystal display unit 12.

As described above, the liquid crystal display device according to the embodiment of the present invention indirectly detects a change in the ambient temperature by detecting a change in the amount of light transmitted through the liquid crystal display unit 12 to detect the change in the ambient temperature. The voltage supplied to is varied. Therefore, even if a change occurs in the ambient temperature, the visibility can be improved without substantially impairing the visibility.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and can be freely changed within the scope of the present invention. For example, in the above-described embodiment, an example in which the light source unit 14 is configured by an LED has been described. However, a backlight that is often provided on the back of the liquid crystal display unit 12 may also be used as the light source unit 14. Further, in FIG. 3, the case where the shape of the opening of the light receiving unit 15 is a rectangular shape has been described as an example, but the shape of the opening can be arbitrarily set.

The liquid crystal display device of the present invention is a black and white or color liquid crystal display device, a liquid crystal display device having segment electrodes, fixed pattern electrodes, or matrix electrodes formed thereon, a static drive system, a passive matrix drive system, and a dynamic matrix drive system. A liquid crystal display device driven by a driving method,
The present invention can be applied to other liquid crystal display devices. In the above-described embodiment, an example has been described in which a plurality of pixels provided in the liquid crystal display unit 12 have a property of not transmitting light when no voltage is applied.
However, the present invention is not limited to this.
Can be applied to a case where a pixel has a characteristic of transmitting light without applying a voltage to the pixel. Also,
In the above embodiment, the light source unit 14 is at least the liquid crystal display unit 1.
In the operation 2, the case where the pixel 13 is constantly illuminated has been described as an example, but in order to reduce current consumption,
It is preferable that the control unit 16 controls the light source unit 14 so that the light source unit 14 emits light only when the transmitted light amount is detected.

[0034]

As described above, according to the present invention,
Since the voltage supplied to the liquid crystal display unit is controlled according to the change in the ambient temperature, even if the ambient temperature changes, the convenience can be improved without substantially impairing the visibility. . In addition, during operation of the liquid crystal display unit, the voltage supplied to the liquid crystal display unit is controlled according to a change in the ambient temperature, so that the display rises quickly even when the ambient temperature is low. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an electrical configuration of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a display area and a non-display area of the liquid crystal display device 12.

FIG. 3 is a perspective view illustrating an example of a light receiving unit 15.

FIG. 4 is a block diagram showing a configuration of a main part of a conventional liquid crystal display device.

FIG. 5 is a diagram illustrating a relationship between an ambient temperature and a voltage applied to a liquid crystal display unit 102 when the same visibility is obtained.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Primary battery (power supply part) 11 Voltage converter (power supply part) 12 Liquid crystal display part 13 Liquid crystal 14 Light source part (detection part) 15 Light receiving part (detection part) 16 Control part 35 Wall part (light shielding part) A2 Non-display area

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09G 3/20 612 G09G 3/20 612D 642 642P F-term (Reference) 2H093 NA06 NC01 NC53 NC57 ND44 5C006 AF46 AF51 AF52 AF53 AF63 BB01 BB11 BF39 BF45 BF46 FA19 5C080 AA10 BB01 BB05 DD20 FF03 JJ02 KK07

Claims (9)

[Claims] 1. A liquid crystal display device comprising: a power supply unit that supplies a voltage to a liquid crystal display unit; and a control unit that controls a voltage that is supplied to the liquid crystal display unit according to a change in ambient temperature. 2. The liquid crystal display device according to claim 1, further comprising a detection unit that detects a change in the ambient temperature by detecting a light amount transmitted through the liquid crystal display unit. 3. The liquid crystal display according to claim 3, wherein the detector is provided on one side of the liquid crystal display, and provided on the other side of the liquid crystal display. 3. The liquid crystal display device according to claim 2, further comprising: a light receiving unit that receives the transmitted light. 4. The liquid crystal display device according to claim 3, wherein the size of the light emitting portion of the light source portion and the size of the light receiving portion are set to be substantially the same. 5. The liquid crystal display device according to claim 3, wherein the light receiving portion is provided with a light blocking portion for blocking light other than the light from the light source portion. 6. The liquid crystal display device according to claim 2, wherein the detection unit is arranged in a non-display area of the liquid crystal display unit. 7. The liquid crystal of the liquid crystal display unit at a position where the detection unit is disposed is set to a light transmitting state at least when the liquid crystal display unit operates. 7. The liquid crystal display device according to claim 6. 8. The control unit according to claim 2, wherein the light amount at a reference ambient temperature and a voltage to be supplied to the liquid crystal display unit are set in advance as a reference light amount and a reference voltage, respectively. The liquid crystal display device according to any one of claims 1 to 5. 9. The control unit according to claim 8, wherein the control unit controls a voltage supplied to the liquid crystal display unit based on a comparison result between the light amount detected by the light receiving unit and the reference light amount.
The liquid crystal display device as described in the above.