GB2226679A

GB2226679A - Display apparatus

Info

Publication number: GB2226679A
Application number: GB8828957A
Authority: GB
Inventors: William H K Chu
Original assignee: Limax Electronics Co Ltd
Current assignee: Limax Electronics Co Ltd
Priority date: 1988-12-12
Filing date: 1988-12-12
Publication date: 1990-07-04
Also published as: GB8828957D0

Abstract

In an optical projection apparatus, an inverted form of an image on a display screen 12 e.g. an LCD, of an image generating unit is displayed at a projection surface 22 of a transparent body secured in an accommodating portion on top of the screen by light LiL2 entering the body and being reflected by the screen 12 and a reflection surface 21 which is oblique to both the screen and the projection surface 22. The transparent body may be made of glass or acrylate and secured to image generating unit by glue or a tongue and groove arrangement. The apparatus may be a timer. In addition to the image on the screen, a pattern or advertisement on an ornamental surface 23 may also be seen from surface 22. <IMAGE>

Description

OPTICAL PROJECTION APPARATUS This invention relates to an optical projection apparatus which projects an inverted form of an image from a first plane onto a second plane which is oblique to the first plane.

For marketing purposes, conventional timers are usually designed as a multifunctional and attractive unit. For example, some of them have a liquid crystal display and an alarm function. Because the design of conventional liquid crystal displays per se is monotonous, it is desirable that a novel function is associated with a liquid crystal display.

It is therefore the main object of this invention to provide a novel timer with a transparent body onto whic the time designating numerals can be projected from a liquid crystal display by means of the refraction and reflection of light.

According to this invention, an optical projection apparatus includes an image generating unit and a transparent body made of a light-permeable material. The image generating unit includes an accommodating means dispcsed at the upper surface thereof, and a display screen disposed at the lower end of the accommodating means so that an image is generated on the display screen. The transparent body is secured within the accommodating means of the image generating device in a manner such that the bottom surface of the transparent body engages with the display screen.To project an inverted form of the image onto the transparent body by the refraction and reflection of light, the transparent body has a projection surface oblique to the display screen, and a reflection surface which is oblique to the projection surface at a predetermined angle and oblique to the display screen at another angle so that light can in turn pass through the transparent body, the display screen, and both the reflection surface of the transparent body and the projection surface of the transparent body. The accommodating means may be either a socket or a dovetail groove. In the case that the accommodating means is a dovetail groove, the transparent body includes a dovetail tongue provided at the bottom end thereof.

Other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of an optical projection apparatus according to this invention; Fig. 2 is an exploded view showing the optical projection apparatus of this invention; Fig. 3 is a sectional side view showing the optical projection apparatus of this invention; Fig. 4 is a schematic view illustrating how two beams of light travel in the optical projection apparatus according to this invention; Fig. 5 is a perspective view showing the timer body of the optical projection apparatus in accordance with this invention; and Fig. 6 is an exploded view of another optical projection apparatus according to this invention.

Referring to Fig. 1, a novel timer or optical projection apparatus of this invention includes a timer body or image generating unit 10 and a transparent body 20 fixed on the timer body 10. As shown in Fig. 2, the timer body 10 has a socket 11 in which the the lower end of the transparent body 20 is fixed. A liquid crystal display screen 12 is installed on the timer body 10 and serves as the bottom wall of the socket 11.

The lower end of the transparent body 20 may be adhered to the display screen 12 by a glue. In this embodiment, the transparent body is made of a glass which can be permeated by light.

Referring to Fig. 3, a first printed circuit board 13 is disposed below the display screen 12. A lamp 14 is positioned adjacent to the lower end of the transparent body 20 for purpose of enabling use of this invention in a dark or badly lit room. A second printed circuit board 15 is adjacent to the lamp 14 so as to connect electrical cords, (not shown), to the first printed circuit board 13. Two batteries 50 are received within a chamber 16 which is formed in the timer body 10. As shown in Fig. 4, inverted numerals and a colon are displayed on the display screen 12 so as to designate time in a known manner. Because the timer body 10 does not form part of this invention, the detailed description thereof is omitted.

Referring to Fig. 5, the transparent body 20 has a reflection surface 21, a projection surface 22 oblique to the reflection surface 21, and an ornametal surface 23 parallel to the projection surface 22. As illustrated, to beams L1, L2 of light enter the transparent body 20 through the projection surface 22.

When the beams L1, L2 respectively reach the points 121, 122 on the display screen 12, they reflect and refract to the reflection surface 21 along the paths 91, 92 which are parallel to the projection surface 22.

The critical angle of the glass is about 41.8 degrees.

When the incident angle 8 of light in the glass is greater than 41.8 degrees, the total reflection of light takes place. Because the beams L1, L2 are incident on the reflection surface 21 at an angle 6 of more than 41.8 degrees with respect to the normals indicated on the reflection suface 21 by parellel dotted lines, said beams respectively reflect to the projection surface 22 along two parallel paths. As a result, an inverted form of the inverted numerals and colon which are displayed on the display screen 12 is projected onto the projection surface 22 of the transparent body 20.

Optionally, a pattern or advertisement can be indicated on the ornamental surface 23 of the transparent body 20. In this manner, in addition to the numerals and colon displayed on the upper portion of the projection surface 22, the pattern or advertisement can also be seen from the projection surface 22.

Alternatively, the transparent body 20 may be made of acrylate.

Referring to Fig. 6, a transparent body 20 is fixed on the timer body 10 by a dovetail tongue and groove engagement in accordance with another embodiment of this invention. In this embodiment, the timer body 10 has a dovetail groove 11', while the transparent bod 20 includes a dovetail tongue 21'.

Claims

CLAIMS:

1. An optical projection apparatus comprising: an image generating unit including an accommodating means disposed at an upper surface thereof, and a display screen disposed at a lower end of said accommodating means so that an image is generated on said display screen; and a transparent body, made of a light-permeable material, secured within said accommodating means of said image generating device in a manner such that a bottom surface of said transparent body engages with said display screen, having a projection surface which is oblique to said display screen, and a reflection surface both oblique to said projection surface at a predetermined angle and oblique to said display screen at another angle so that light can in turn pass through said transparent body, said display screen, and both said reflection surface of said transparent body and said projection surface of said transparent body, whereby, ' an inverted form of said image can be displayed on said projection surface by means of refraction and reflection of light.

2. An optical projection apparatus as claimed in Claim 1, wherein said transparent body is made of a glass.

3. An optical projection apparatus as claimed in Claim 1, wherein said transparent body is made of acrylate.

4. An optical projection apparatus as claimed in Claim 1; wherein said accommodating means is a socket.

5. An optical projection apparatus as claimed in Claim 4, wherein said image generating unit includes a glue for attaching said transparent body thereto.

6. An optical projection apparatus as claimed in Claim 1, wherein said accommodating means is a dovetail groove, and wherein said transparent body includes a dovetail tongue engaged with said dovetail groove.

7. An optical projection apparatus substantially as described hereinbefore with reference to the accompanying drawings.