JPH1124579A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To illuminate the display part of a liquid crystal display element with nearly uniform brightness by providing the liquid crystal display element, a straight tube-like light source provided on the rear side of the liquid crystal display element and a columnar optical member provided nearly in parallel with the straight tube-like light source between the liquid crystal display element and the straight tube-like light source. SOLUTION: The straight tube-like light source 8 is disposed on the rear side of the liquid crystal display element 4. A lens 11 which is the columnar optical member is disposed between the element 4 and the light source 8. Then, the lens 11 is disposed so as to make a center line B and the center line C of a cathode tube 8 nearly in parallel with each other. Also, an interval D between the cold cathode tube 8 and the lens 11, namely a distance between the center line B and the center line C corresponds to the focal distance of the lens 11. The diameter of the lens 11 corresponds to the length of the display part 7 in a longitudinal direction. By this constitution, a light beam emitted from the cold cathode tube 8 is changed into the light beam nearly in parallel with an optical axis by the lens 11, so that the display part 7 of the element 4 is illuminated with uniform brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device, and more particularly to a display device having a liquid crystal display element.

[0002]

2. Description of the Related Art Hitherto, various display devices using liquid crystal display elements have been proposed.
No. 0, JP-A-2-107123. As shown in FIG. 4, such a display device includes a light source 2 for illuminating the liquid crystal display element 1 from behind, so that the display section of the liquid crystal display element 1 can be viewed well even at night or the like. .

[0003]

However, the light source 2 of the above-described display device has a problem that the display portion of the liquid crystal display element 1 cannot be illuminated with uniform brightness. That is, light emitted from the light source 2 and transmitted through the central portion of the liquid crystal display element 1 reaches the observer 3, but light transmitted through peripheral portions of the liquid crystal display element 1 deviates from the optical axis A and reaches the observer 3. Therefore, the central portion of the display portion of the liquid crystal display element 1 is viewed bright, and the peripheral portions are viewed relatively dark.

In order to solve this problem, a plate-shaped optical member such as a Fresnel lens or a lenticular lens is provided so that light emitted from the light source 2 is refracted by the lens so as to be substantially parallel to the optical axis A. By doing so, it has been proposed to illuminate the display section of the liquid crystal display element 1 with substantially uniform brightness, for example, as disclosed in Japanese Utility Model Publication No. 6-24856. However, the Fresnel lens and the lenticular lens are expensive due to their complicated shapes, and there is a risk that the display device becomes expensive accordingly. The present invention
In view of the above problems, it is an object of the present invention to provide a display device capable of illuminating a display section of a liquid crystal display element with substantially uniform brightness.

[0005]

According to the present invention, there is provided a liquid crystal display device, a straight tube light source provided behind the liquid crystal display device, a liquid crystal display device and the straight tube light source. And a columnar optical member provided substantially in parallel with the straight tube light source.

Further, in the present invention, the optical member has a columnar shape.

Further, the present invention has a reflecting member for reflecting the light emitted from the straight tubular light source to the liquid crystal display element side.

Further, the present invention has a semi-transmissive member for reflecting light emitted from the straight tubular light source and transmitted through the liquid crystal display element.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A straight tubular light source 8 is disposed behind a liquid crystal display element 4. A columnar optical member 11 is provided between the liquid crystal display element 4 and the straight tubular light source 8. A reflecting member 12 for reflecting light emitted from the straight tubular light source 8 toward the liquid crystal display element 4 is provided. Further, a semi-transmissive member 14 for reflecting light emitted from the straight tubular light source 8 and transmitted through the liquid crystal display element 4 is provided.

[0010]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a first embodiment.

Reference numeral 4 denotes a liquid crystal display element. The liquid crystal display element 4 is a liquid crystal cell in which liquid crystal is sealed between a pair of transparent substrates 5 and film polarizers (not shown) are adhered to both front and rear surfaces of the liquid crystal cell. . The liquid crystal display element 4 is of a so-called dot matrix type, and has a display section 7 in which a number of segments 6 are arranged in a matrix. The liquid crystal display element 4 can display various characters, figures, and the like by setting each segment 6 in a transmissive state or a non-transmissive state. Reference numeral 8 denotes a cold cathode tube (straight tube light source). The cold cathode tube 8 is disposed behind the liquid crystal display element 4. The cold-cathode tube 8 has a straight tubular light emitting portion 9 and terminal portions 10 provided at both ends of the light emitting portion 9.

Reference numeral 11 denotes a lens (optical member). The lens 11 is made of a translucent material such as acrylic or glass. The lens 11 has a columnar shape and is disposed substantially parallel to the cold cathode tube 8. That is, the lens 11 has its center line B
And the center line C of the cold-cathode tube 8 are arranged substantially in parallel. The distance D between the cold-cathode tube 8 and the lens 11, that is, the distance between the center line B and the center line C corresponds to the focal length of the lens 11. The diameter of the lens 11 corresponds to the length of the display unit 7 in the vertical direction.

FIG. 2 is a diagram showing a second embodiment in which the present invention is applied to a head-up display. The same portions as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

A cold cathode tube 8 is provided behind the liquid crystal display device 4, and a lens is provided between the liquid crystal display device 4 and the cold cathode tube 8.
11 are arranged. Reference numeral 12 denotes a reflector (reflection member). The reflector 12 is disposed behind the cold cathode fluorescent lamp 8,
The light emitted from the cold cathode tube 8 is reflected to the liquid crystal display element 4 side. A mirror 13 reflects light transmitted through the liquid crystal display element 4 to a combiner described later. 14 is a combiner (semi-transmissive member), and this combiner 14 is a mirror 13
Is reflected to the observer 15 side. Observer
Reference numeral 15 allows the display unit 7 to be visually recognized by being superimposed on the scenery.

FIG. 3 is a diagram showing a third embodiment in which the present invention is applied to a head-up display. In addition, the first,
The same parts as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

A lens 16 and a lens 17 are provided between the liquid crystal display element 4 and the cold cathode tube 8. These lenses
16 and 17 have a semi-cylindrical shape such that the cylinder is divided into two by a plane passing through the center line. The lenses 16 and 17 have cylindrical surfaces 16a and 17a and planes 16b and 17b, respectively, and are disposed with the cylindrical surfaces 16a and 17a facing the liquid crystal display element 4. The reflector 12 is provided on the rear side of the cold cathode tube 8 and reflects light emitted from the cold cathode tube 8 to the liquid crystal display element 4 side. The combiner 14 reflects the light transmitted through the liquid crystal display element 4 to the viewer 15 side.

According to each embodiment described above, the cold cathode fluorescent lamp 8
Can be converted into light substantially parallel to the optical axis by the lenses 11, 16 and 17.
Can be illuminated with substantially uniform brightness. The lenses 11, 16, and 17 are less expensive than the Fresnel lens and the lenticular lens described in the conventional example, and there is no fear that the display device becomes expensive.

The lenses 16 and 17 may be semi-cylindrical as in the third embodiment, but are preferably cylindrical lenses 11 having a short focal length as in the first and second embodiments.
The distance D between the cold cathode tube 8 and the lens 11 can be reduced, and the size of the display device can be reduced. Although the straight tube light source of this embodiment is the cold cathode tube 8, it may be a hot cathode tube, for example.

[0019]

According to the present invention, there is provided a liquid crystal display device, a straight tube light source provided behind the liquid crystal display device, and a space between the liquid crystal display device and the straight tube light source substantially parallel to the straight tube light source. And a provided columnar optical member,
The liquid crystal display element can be illuminated with substantially uniform brightness.

Further, according to the present invention, the optical member has a cylindrical shape, so that the distance between the straight tubular light source and the optical member can be reduced, and the display device can be downsized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a side view showing a second embodiment of the present invention.

FIG. 3 is a side view showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 4 Liquid crystal display element 8 Cold cathode tube (straight tube light source) 11 Lens (optical member) 12 Reflector (reflective member) 14 Combiner (semi-transmissive member) 16 Lens (optical member) 17 Lens (optical member)

Claims (4)

[Claims] 1. A liquid crystal display device, a straight tubular light source provided behind the liquid crystal display device, and a columnar shape provided substantially parallel to the straight tubular light source between the liquid crystal display device and the straight tubular light source. And an optical member. 2. The display device according to claim 1, wherein the optical member has a columnar shape. 3. The display device according to claim 1, further comprising a reflection member configured to reflect light emitted from the straight tubular light source toward the liquid crystal display element. 4. The display device according to claim 1, further comprising a semi-transmissive member for reflecting light emitted from the straight tubular light source and transmitted through the liquid crystal display element. Display device.