JPH1185055A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to improve the efficiency of a printed circuit board with simple constitution by arranging LEDs in the outer peripheral part of a display region and forming display region parts to white or to the same system color as the light emission colors of the LEDs. SOLUTION: A liquid crystal display element 2 is divided by windows to three blocks and 14 pieces of the LEDs 4 are arranged on the outer peripheral parts which are not directly visible from the three windows in order to illuminate these blocks with uniform brightness. The parts 1' enclosed by the frame of an LED holder 3 in the part of the printed circuit board 1 behind the liquid crystal display element 2 are all coated white. The light emitted from the LEDs is irregularly reflected by the surface of the printed circuit board 1' and is cast to a diffusion plate 5 and, therefore, the entire surface of the liquid crystal display element 2 may be brightly illuminated. At this time, the inside walls of the LED holder 3 are all coated white as well. As a result, the unequal luminance of a back light may be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for operation and display of household electric appliances.

[0002]

2. Description of the Related Art In electric cooking utensils such as IH cooking heaters, liquid crystal display devices have been receiving attention for the purpose of improving operability. In order to make the liquid crystal display device more easily viewable, various backlight devices for illuminating from behind the device have been devised.

A conventional backlight device will be described below with reference to FIGS. In FIG. 6, 1 is a printed circuit board, 2 is a liquid crystal display element, 3 is an LCD holder that supports the liquid crystal display element 2 and does not allow the light of the backlight to escape outside, 4 is the LED of the backlight, and 5 is the liquid crystal. This is a diffusion plate that is provided on the lower surface of the display element and diffuses light.

A large number of LEDs 4 of the backlight are arranged on the printed board just below the liquid crystal display element 2 so as to uniformly illuminate the rear surface of the liquid crystal display element 2.

Another conventional example is a side-view type backlight device shown in FIG.

In the case of this method, in FIG. 7, a side emission type LED is used as the backlight LED 4,
The light from the LEDs 4 was reflected on the reflection plate 12 to illuminate the rear surface of the liquid crystal display element 2.

[0007] A conventional example of claim 7 will be described. In the circuit diagram of the IH cooking heater shown in FIG. 8, 20 is a 200 V AC power supply, 21 is an insulation transformer of a right burner control circuit, 22 is an insulation transformer of a left burner control circuit, 23 is a rectifier circuit of a right burner control circuit, 24
Is the rectifier circuit of the left burner control circuit, 25 is the right burner I
H coil circuit rectifier circuit, 26 is a left burner IH coil circuit rectifier circuit, 27 is a right burner IH coil, 28 is a left burner IH coil, 29 is a right burner control circuit, 3
Reference numeral 0 denotes a left burner control circuit, 31 denotes a nichrome wire heater constituting a central burner, 32 denotes a relay for controlling the heater 31, 2a denotes a liquid crystal display element for displaying operation states of the left burner and the central burner, and 2b denotes right. Is a liquid crystal display element for displaying the operation state of the burner.

In FIG. 8, since the right circuit block 33 and the left circuit block 34 drive different IH burners, power supplies are constituted by separate rectifier circuits 25 and 26. Is applied with a voltage of 200V.

Therefore, the distance between the liquid crystal display elements 2a and 2b in the right circuit block 33 and the left circuit block 34 is approximately 2
Since a high voltage of 00V is applied, the liquid crystal display element 2a
The liquid crystal display element 2b and the liquid crystal display element 2b are configured as separate components and are separately wired to ensure an insulation distance between the liquid crystal display elements.

The liquid crystal display element generally needs to have a distance of at least 2 mm from the outer periphery to the visible region. When the liquid crystal display device 2a and the liquid crystal display device 2b are arranged side by side, the distance between the respective visible regions becomes equal to that of the liquid crystal display device. Even when the elements are in close contact with each other, 4 mm and an insulation distance of 3 mm require a total of 7 mm or more. Even if the insulation distance is 1 mm via an insulator or the like, a total of 5 mm or more is required.

Therefore, the interval between the adjacent visible regions must be widened. Even if the structure shown in FIG. 9 is arranged, the interval between the windows of the display unit becomes large as shown in FIG. Was smaller overall.

[0012]

In the above-mentioned conventional backlight device, it is necessary to use a large number of LEDs in order to prevent unevenness in brightness due to the use of direct light of the LEDs. In addition, since a large number of LEDs are arranged immediately below the liquid crystal display element, other parts such as an IC and a microcomputer cannot be arranged in that part, and the use efficiency of the printed circuit board is poor and the area of the printed circuit board becomes large. There was.

Further, in the case where the LEDs are arranged in one line on one side, the opposite side where the LEDs are not arranged becomes dark, and the configuration of the reflection plate and the diffusion plate for correcting this is complicated. In addition, since the LEDs are densely arranged on one side, the wiring of the printed circuit board is restricted due to the soldering lands of the terminals of the LED, and it becomes difficult to perform high-density wiring on the printed circuit board. was there.

In the case where the two circuit blocks having different voltages are configured as separate components, the left and right display units must be arranged apart from each other in order to secure an insulation distance. The area of the part became small, and the design was unnatural.

Accordingly, the present invention provides a relatively small number of LEDs.
It is an object of the present invention to realize a backlight device of a liquid crystal display element having a simple structure using a printed circuit board and improving the use efficiency of a printed circuit board.

Further, according to the present invention, the liquid crystal display elements of the two circuit blocks are formed in one liquid crystal display element without electrically interfering with each other and with a sufficient insulation distance, so that the liquid crystal display element can be wider. It is a second object of the present invention to obtain a display unit and to enable a display configuration having a degree of freedom in design.

[0017]

According to the present invention, there is provided a backlight device for illuminating a liquid crystal display element from behind with an LED disposed on a printed circuit board. And the display area of the liquid crystal display element of the printed circuit board is white or a color similar to the emission color of the LED.

In order to achieve the second object, a liquid crystal display block having different high-voltage AC voltage systems is provided,
The liquid crystal display block is wired on the same base material such that the electric field strength is equal to or less than 100 V / mm at the distance between adjacent wiring patterns, and common liquid crystal is arranged inside the base material to form an integral part. .

[0019]

According to the first aspect of the present invention, there is provided a backlight device for illuminating a liquid crystal display element from behind with an LED disposed on a printed circuit board, wherein the LED is provided outside a display area of the liquid crystal display element. A microcomputer or the like can be arranged on the printed circuit board behind the liquid crystal display element by disposing the display area of the liquid crystal display element on the printed circuit board in white or a color similar to the emission color of the LED while disposing the display area on the printed circuit board. In addition, there is an effect that a backlight device with less luminance unevenness can be obtained by the indirect light of the LED.

According to a second aspect of the present invention, there is provided a backlight device for illuminating a liquid crystal display element from behind with an LED disposed on a printed circuit board, and the LED is disposed at an outer peripheral portion of a display area of the liquid crystal display element. In addition, by providing a raised reflector at the center in the display area of the liquid crystal display element of the printed circuit board, the indirect light of the LED is reflected toward the center of the liquid crystal display element, and the brightness unevenness is reduced. This has the function of obtaining a backlight device.

According to a third aspect of the present invention, there is provided, in particular, an LCD holder for forming a side wall of the LED and mounting and fixing the liquid crystal display element thereon, and the reflection plate is formed of a white or black molded integrally with the LCD holder. By having a color similar to the emission color of the LED, a backlight device having a simple configuration with a small number of parts and a small luminance unevenness can be obtained.

According to a fourth aspect of the present invention, in particular, the side wall near the LED is formed into a spherical shape so as to concentrate the light at the center of the display area, so that the indirect light of the LED is applied to the center of the liquid crystal display element on the wall surface. This has the effect of obtaining a backlight device with less luminance unevenness.

The invention described in claim 5 has an effect that a backlight device with less luminance unevenness can be obtained by making the surfaces of the side wall and the reflector near the LED mirror-finished.

According to a sixth aspect of the present invention, in particular,
By mixing a light diffusing agent into the lens, L
Since the light emitted from the ED is made uniform and is reflected on the wall surface or the reflection plate and hits the rear surface of the liquid crystal display element, it has an effect that a backlight device with less uneven brightness can be obtained.

According to a seventh aspect of the present invention, there is provided a liquid crystal display block having different high-voltage AC voltage systems, and the distance between the wiring patterns adjacent to the liquid crystal display block is adjusted so that the electric field strength becomes 100 V / mm or less. By wiring on the same base material and arranging a common liquid crystal inside the base material to form an integrated part, the number of parts is reduced and a wider and easier-to-view display unit is obtained.

[0026]

【Example】

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural view of a first embodiment of the present invention, which is a partial sectional view of a front view and a side view.

In FIG. 1, 1 is a printed circuit board, 2 is a liquid crystal display element, 3 is an LCD holder which supports the liquid crystal display element 2 and forms a frame so that the light of the LED backlight does not escape outside. 5 is a diffusion plate which is located on the back of the liquid crystal display element and diffuses light, 6 is a microcomputer for controlling these display circuits, 7 is a switch for operating the device, 8 Is a key top that transmits power from a finger to press switch 7, 9
Is a jumper wire, 10 is a resistor, and 11 is an IC. Further, the portion surrounded by the frame of the LCD holder and painted white on the printed circuit board is defined as 1 '.

FIG. 2 is a structural view of an embodiment according to claims 2 to 6 of the present invention, and is a partial sectional view of a front view and a side view similarly to FIG.

Reference numeral 12 denotes a reflector for uniformly irradiating the light of the LED 4 to the liquid crystal display element, and reference numeral 13 denotes a jumper connected to be integrally formed with the LCD holder 3, and the other components are the same as those in FIG.

FIG. 3 shows a display portion of the liquid crystal display element 2 according to the embodiment of the present invention. Reference numeral 2 denotes a fully lit state of one connected liquid crystal display element, which is used to operate three burners. It is divided into three parts by windows.

FIG. 4 is an enlarged cross-sectional view of the mounting portion of the LED 4 of FIG. 2 according to the embodiment of the present invention as viewed from the side, 2 is a liquid crystal display element, 3 is an LCD holder, and 4 is a side emission type LE.
D, 5 is a diffusion plate, 12 is a reflection plate, 14 is an LED element, 1
5 is a side wall formed as a part of the elliptical shape of the LCD holder 3, 16 is a diffusing agent mixed in the lens of the LED, and the light emitted from the LED element 14 is the side wall 15 as shown by the arrow.
This indicates that the light is reflected evenly on the center of the window due to the reflection on the reflection plate 12 or the reflection.

In the embodiment, the liquid crystal display element 2 is shown in FIG.
As shown in FIG. 3, it is divided into three blocks by a window, and in order to illuminate it with equal brightness, as shown in FIG. 1, 14 LEDs 4 are arranged in an outer peripheral portion which is not directly visible from the three windows. doing.

The liquid crystal display element 2 on the printed circuit board 1
Part 1 surrounded by the frame of LCD holder 3
Are painted in white, the light emitted from the LEDs is diffusely reflected on the surface of the printed circuit board 1 'and impinges on the diffusion plate 5, so that the entire surface of the liquid crystal display element 2 can be brightly illuminated. At this time, the entire inner wall of the LCD holder 3 is also painted white.

Since there is a space in the rear part of the liquid crystal display element 2 where components can be arranged, a surface-mounted microcomputer 6 is arranged on the back surface, and a jumper wire 9, a resistor 10, an IC 11 and the like are arranged on the front surface. Have been placed. At this time, the color of the IC mold disposed on the surface is desirably white.

Further, when the area of the liquid crystal display element 2 is large, the central portion of the window is far from the LED 4 as a light source, so that the window may be dark.

As an embodiment in the case where the area of the liquid crystal display element 2 is thus increased, as shown in FIG.
2 is arranged at the center of each of the three blocks.

In this manner, as shown in FIG. 3, light emitted from the side emission type LED 4 is
By collecting the light at the central portion of the window by reflecting the light on the side wall of the holder 3 and the reflecting plate 12, the central portion of the window can be brightened, and the diffuser plate 5 can be illuminated from behind so as to have substantially uniform brightness. it can.

Here, the reflection plate 12 is connected to the side wall of the LCD holder 3 by a jumper 13 and is formed of white plastic integrated with the LCD holder 3 and is constituted as a single component. Variations in the positional relationship can be reduced as compared with the case where the components are formed separately.

Further, the side wall 15 in FIG. 3 forms a spherical shape which is almost approximated to an elliptical shape in order to concentrate light from the LED 4 on a portion having a small brightness. It is located almost at the focal point.

The side wall 15 and the reflecting plate 12 having a spherical shape are mirror-finished to reflect the light of the light source to a target portion, and the wall of the flat portion of the inner surface of the LCD holder 3 and the portion of the jumpsuit 13 are formed. The mirror finish is used instead of mirror finish to diffusely reflect light. Also, LE
The diffusing agent 16 is put into the lens of D4 to make it light milky, and the light emitted from the LED element 14 is appropriately scattered. It will glow evenly.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a block diagram of a circuit according to a seventh embodiment of the present invention. In FIG. 5, 20 is 200V A
C power supply, 21 is an insulation transformer of the right burner control circuit, 2
2 is an insulation transformer of a left burner control circuit, 23 is a rectifier circuit of a right burner control circuit, 24 is a rectifier circuit of a left burner control circuit, 25 is a rectifier circuit of a right burner IH coil circuit, and 26 is a rectifier of a left burner IH coil circuit. Circuit, 27
Is a right burner IH coil, 28 is a left burner IH coil, 29 is a right burner control circuit, 30 is a left burner control circuit, 31 is a nichrome wire heater constituting a central burner, 32 is a relay for controlling the heater 31, and 2 is each A liquid crystal display element for displaying the operation state of the burner.
a is a portion for displaying the operation status of the left burner and the center burner in one liquid crystal display element, and 2b is a portion for displaying the operation status of the right burner.

In FIG. 5, a voltage of about 200 V is applied between the right burner circuit and the left burner circuit. Therefore, a voltage of about 200 V is applied between the left display portion 2a and the right display portion 2b of the liquid crystal display element 2. Voltage is applied. In order to form electrodes and wirings on one glass substrate and incorporate them as one liquid crystal display element, a sufficient insulation distance is required between the electrode group from the right burner control circuit and the electrode group from the left burner control circuit. The electric field strength between the adjacent wiring patterns is set to 100 V / mm so that the liquid crystal is not turned on due to the influence of the electric field due to the high voltage and the wiring in the liquid crystal display element 2 is kept at 3 mm or more. Set the insulation distance so that:

In this embodiment, since the applied voltage is 200 V, the wiring is performed while maintaining the insulation distance of 2 mm or more.

As described above, by integrating the liquid crystal display blocks of the left and right burner circuits into one liquid crystal display element, an integrated liquid crystal as shown in FIG. 2 is obtained. Is possible up to 2 mm in this embodiment.

The distance m between the windows of the display unit shown in FIG.
However, as compared with the case where an insulation distance of 1 mm is required between liquid crystal display elements and at least 5 mm is necessary, the width of the window can be increased because the width is small, and the entire display unit is limited. It is possible to make it much larger in the space.

[0048]

As described above, according to the first aspect of the present invention, the side emission type LEDs are arranged on the printed circuit board at the outer periphery of the display area of the liquid crystal display element, and the side faces of the LCD holder are arranged. And the rear part of the liquid crystal display element on the printed circuit board is composed of white or a color similar to the emission color of the LED, so that the indirect light reflected on each part is applied to the diffusion plate on the back surface of the liquid crystal display element, The effect of reducing the brightness unevenness of the backlight is obtained, and the LEDs are arranged at an appropriate distance, so that components such as a microcomputer can be arranged on the printed circuit board behind the liquid crystal display element, so that the area of the printed circuit board is The effect that it can be made small as is obtained.

According to the second aspect of the present invention, when the area of the liquid crystal display element increases, the central portion becomes darker than the peripheral portion. By providing a reflecting plate having a swelling, the indirect light of the LED is reflected toward the center of the liquid crystal display element, and the effect of eliminating dark portions and reducing luminance unevenness can be obtained.

According to the third aspect of the present invention, the reflection plate is made of plastic of white or a color similar to the color of the LED, which is integrally formed with the LCD holder for mounting and fixing the liquid crystal display element. By doing so, it is possible to obtain an advantageous effect that a backlight device with a small number of components and a simple configuration with less luminance unevenness and easy to see can be obtained.

According to the fourth aspect of the present invention, L
By forming the side wall in the vicinity of the ED into a spherical shape in order to concentrate the light on the central part of the display area, the radiated light of the LED is reflected on the wall surface toward the central part of the liquid crystal display element, and the liquid crystal display element is formed. Even if the area is large, it is possible to obtain an advantageous effect that a backlight device with less luminance unevenness and easy to see can be obtained.

According to the fifth aspect of the present invention, L
On the inner wall of the CD holder, the spherical side wall near the LED and the surface of the reflector with a bulge at the center are mirror-finished to concentrate the light emitted from the LED at the center. In a portion where there is no effect of concentrating light, an effect of further reducing luminance unevenness can be obtained by irregularly reflecting light.

According to the sixth aspect of the present invention, L
By mixing a light diffusing agent into the ED lens, LE
The light emitted from the D element is irregularly reflected by the diffusing agent, and the LED
Since the light emitted from the light source is made uniform and reflected on the wall surface or the reflection plate and hits the rear surface of the liquid crystal display element, an effect of obtaining a backlight device with less luminance unevenness and easy to see is obtained.

According to the seventh aspect of the present invention, in a circuit configuration having different AC power supply voltage systems, the liquid crystal display element is provided on one base material so that the insulation distance between the electrode and the wiring inside the liquid crystal is set to a certain value or more. By maintaining it as an integral part, it is possible to obtain a wider and easier-to-read display unit in a limited space, reduce the number of parts, simplify assembly, and reduce costs and improve reliability. Is also obtained.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is another structural view of the liquid crystal display device.

FIG. 3 is a diagram showing a display panel of the liquid crystal display device.

FIG. 4 is a sectional view of an essential part of the liquid crystal display device.

FIG. 5 is a circuit diagram of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 6 is a structural view of a conventional liquid crystal display device.

FIG. 7 is another structural view of the liquid crystal display device.

FIG. 8 is a circuit diagram of the same liquid crystal display device.

FIG. 9 is another structural view of the liquid crystal display device.

FIG. 10 is a diagram showing a display panel of the liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Liquid crystal display element 3 LCD holder 4 LED 5 Diffusing plate 12 Reflecting plate 15 Side wall 16 Diffusing agent

 ──────────────────────────────────────────────────の Continued on the front page (72) Yoshihiro Yamashita 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A backlight device for illuminating a liquid crystal display element from behind with an LED disposed on a printed circuit board, wherein the LED is disposed at an outer peripheral portion of a display area of the liquid crystal display element, and A liquid crystal display device in which the display region of the liquid crystal display element is white or a color similar to the emission color of the LED. 2. A backlight device for illuminating a liquid crystal display element from behind with an LED disposed on a printed circuit board, wherein the LED is disposed at an outer peripheral portion of a display area of the liquid crystal display element, and A liquid crystal display device comprising a centrally raised reflecting plate provided in a display area of the liquid crystal display element. 3. An LCD holder for forming a side wall of the LED and mounting and fixing a liquid crystal display element thereon, wherein the reflection plate is white or a color similar to the emission color of the LED integrally formed with the LCD holder. 3. The liquid crystal display device according to claim 2, wherein 4. The liquid crystal display device according to claim 1, wherein a side wall near the LED has a spherical shape so as to concentrate light at a central portion of the display area. 5. The liquid crystal display device according to claim 4, wherein the surfaces of the side wall and the reflector near the LED are mirror-finished. 6. The liquid crystal display device according to claim 1, wherein the LED has a lens in which a light diffusing agent is mixed. 7. A liquid crystal display block having different high-voltage AC voltage systems, wherein the liquid crystal display block is arranged on the same base material so that the distance between adjacent wiring patterns is 100 V / mm or less. A liquid crystal display device in which a common liquid crystal is disposed inside a base material to form an integral part.