JPH0442830Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an overhead projector (hereinafter also referred to as OHP) that projects the display contents of a transmissive liquid crystal display element (hereinafter referred to as liquid crystal element). .

(Prior Art) Conventionally, as shown in FIG. 2, the applicant proposed an OHP 3 that drives a dot matrix type panel-shaped liquid crystal element 2 based on an image signal from a personal computer (hereinafter also referred to as a personal computer) 1. (Patent Application No. 114498, 1982).

(Problems to be Solved by the Invention) The conventional OHP3 can not only be used in the general usage of displaying the content displayed on the original sheet on a screen (not shown), but also in the computer 1.
can be displayed on the screen via the liquid crystal element 2, but it has not been possible to read the contents of the document sheet.

In view of the above-mentioned conventional problems, the present invention aims to provide an OHP that can also read the contents of a document sheet using a liquid crystal element.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention drives a dot matrix panel-shaped transmissive liquid crystal display element based on an image signal from an image information source such as a personal computer, and In an overhead projector that projects image information using It is characterized by being provided with a light receiving element that detects the brightness of light projected onto the original sheet located on the upper surface or lower surface of the liquid crystal display element, and a reading section that reads the display content of the original sheet based on the detection signal of the light receiving element. shall be.

(Function) According to the present invention, the control means causes the liquid crystal element to
Light is controlled to pass pixel by pixel, whereby the light receiving element detects the brightness of the original sheet corresponding to the passing pixel, and the reading section reads this based on the detection signal. Therefore, when all pixels of the liquid crystal display are operated as described above, the entire display content of the document sheet is read.

(Embodiment) FIGS. 1, 3 to 7 show an embodiment of the present invention, and the same components as those of the conventional example are denoted by the same reference numerals. That is, 2 is a liquid crystal element, 3 is
It is an OHP. The OHP 3 includes a box-shaped OHP main body 30 with a pair of inverted trapezoidal sides, an L-shaped arm 31 rotatably attached to the upper side of the OHP main body 30, and an L-shaped arm 31 at the tip of the arm 31. It consists of a head 32 that is detachably attached to the OHP.
A light source 33 and a reflecting plate 34 that reflects the light from the light source 33 upward are provided in the main body 30, and the light is reflected upward.
Stage 35 made of glass plate of OHP main body 30
The light is projected onto the liquid crystal element 2 placed on the stage 35. In addition, the head 3
2 has a pair of triangular side surfaces, the bottom surface and one side surface in the width direction are open, and a mirror 36 housed in the head 32 allows the light from the light source 33 to enter from the bottom opening, and further opens the side surface. The light is projected onto a screen 37 through the opening.

FIG. 4 shows another example of the head 32, in which a lens 32a that focuses the light projected above the OHP main body 30 and a photodiode 32b that receives the focused light are provided in the head 32'. , the brightness of the light is converted into an electrical signal. Incidentally, a recess 38 into which the head 32 fits is provided in the upper part of the front side of the OHP main body 3.

FIG. 5 shows a drive control circuit for the liquid crystal element 2, in which 20 is an interface circuit for a communication line (hereinafter referred to as an interface circuit) connected to the personal computer 1 that transmits image signals, and 21 is a control circuit. , reads a character signal from the character generator 22 based on the image signal of the interface circuit 20, stores the character signal etc. in the storage device 23, and furthermore, reads the character signal etc. from the storage device 23 into the drive circuit 24. It is now output to . Further, the control circuit 21 drives and controls the light to pass through each pixel 2a of the liquid crystal element 2 at a predetermined time interval via the drive circuit 24,
The photodiode 32b is synchronized with the control signal.
The detection signal of is stored in the storage device 23, the brightness of the original sheet 40 corresponding to each pixel 2a is read into the storage device 23, and the image information read into the storage device 23 is read. is sent to the computer 1, and the computer 1's CRT
It is now possible to display it at

According to this embodiment, when the original sheet 40 is placed on the stage 35 of the OHP main body 30, the contents of the original sheet 40 are displayed on the screen 37 in the same way as a general OHP 3.

Further, when the liquid crystal element 2 is placed on the stage 35, the image information of the personal computer 1 is transferred to the interface circuit 20, the control circuit 21, the character generator 22, the storage device 23, and the drive circuit 24. The image is displayed on the liquid crystal element 2 via the screen 37, and further displayed on the screen 37.

Further, a head 32' having the photodiode 32b is attached to the tip of the arm 31, and the liquid crystal element 2 is placed on the stage 35.
When each of the original sheets 40 is placed on the liquid crystal element 2, the control circuit 21 causes the pixels 2a (8×12) of the liquid crystal element 2 to be illuminated one by one from the light source 33 at a predetermined time. light passes through. Therefore, as shown in FIG. 6, since the document sheet 40 corresponding to the pixel 2a' is transparent when passing through the pixel 2a', the photodiode 32b detects that the brightness is strong; Further, when the light passes through the pixel 2a'', the original sheet 40 corresponding to the pixel 2a'' is opaque, so the photodiode 32b detects that the brightness is weak. By performing this operation for all pixels 2a of the liquid crystal element 2, the character "A" shown in FIG. 6 is detected, and the information "A" is stored in the storage device 23.

Furthermore, as shown in FIG. 7, one side in the width direction of the OHP main body 30 is brought into contact with, for example, a floor surface 50, and the arm 31 is rotated to bring the head 32 into contact with the floor surface 50. When the screen 37 is not used, the liquid crystal element 2
The image information of the personal computer 1 is displayed, and the contents of the image can be visually recognized.

(Effects of the invention) As explained above, the invention drives a dot matrix panel-shaped transmissive liquid crystal display element based on an image signal from an image information source such as a personal computer, and displays image information using a light source. In an overhead projector for projecting, a control means for driving the transmissive liquid crystal display element to pass light pixel by pixel after a predetermined period of time; A light-receiving element that detects the brightness of light projected onto the original sheet located on the bottom surface and a reading section that reads the displayed content of the original sheet based on the detection signal of the light-receiving element are provided, so that image information of the personal computer, etc. Of course, it is possible to display the
It has the advantage that the contents of the original sheet can be read using the transmissive liquid crystal display element.

[Brief explanation of the drawing]

1, 3 to 7 show an embodiment of the present invention. FIG. 1 is a perspective view of an overhead projector, and FIG. 2 is a conventional overhead projector connected to a personal computer. 3 is an explanatory diagram showing the structure of the overhead projector, FIG. 4 is an explanatory diagram showing the structure of the head portion, and FIG. 5 is a block diagram showing drive control of the transmissive liquid crystal display element. , FIG. 6 is an explanatory diagram showing the state of light passing through a predetermined pixel, and FIG. 7 is a side view showing the state when image contents are directly displayed on the overhead projector main body. In the figure, 1... image information source (computer), 2...
Transmissive liquid crystal display element (liquid crystal element), 2a... pixel,
3... Overhead projector (OHP), 2
1...Control circuit, 23...Storage device, 32b...
Light receiving element (photodiode), 40... Original sheet.

Claims (1)

[Scope of utility model registration request] In an overhead projector that drives a dot matrix type panel-shaped transmissive liquid crystal display element based on an image signal from an image information source such as a personal computer and projects image information using a light source, the transmissive liquid crystal display element control means for driving the light to pass through each pixel at a predetermined time interval, and detecting the brightness of the light projected onto the transmissive liquid crystal display element and the original sheet located on the upper surface or the lower surface of the transmissive liquid crystal display element. What is claimed is: 1. An overhead projector comprising: a light-receiving element; and a reading section that reads display contents of the document sheet based on a detection signal from the light-receiving element.