JPH0484191A - Back projection type display device - Google Patents

Abstract

PURPOSE:To provide the back projection type display device provided with a digitizer function which can make position assignment by providing a controller which regards IR light, when detected by an IR sensor, as the presence of the input of the instruction to the prescribed point of a transmission type screen to which the present IR rays are projected by an IR projecting means. CONSTITUTION:The IR light past a liquid crystal device 8 to be scanned is reflected by the front end of a light pen 12 and is detected by the IR sensor 13, by which the light is converted to an electric signal. This signal is outputted to a CPU 15. In which position on the screen 11 the position of the previous IR reflected light corresponds is judged in the CPU 15 from the output signal of an LC driving circuit 21 and this position is stored in a memory 16. The information stored in the memory 16 is transmitted via the CPU 15 to a character and graphic signal generator 17, by which the information is converted to video signal data and the video data drawn by a light pen 12 is superposed on the video projected on the screen 11. The position assignment is executed in this way regardless of the outside shape and the size of the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear projection type display device, and more particularly to a rear projection type display device having a digitizer function for designating a specific position of a display.

[Conventional technology]

Conventional devices with a digitizer function that can specify a specific position on the display include those that have multiple LEDs and optical sensors placed around the display so that they face each other, and the position is confirmed by light detection by the optical sensor. be. There are also those that use ultrasonic waves as a detection source. In this device, an ultrasonic source is used as the pencil head, and the position of the pencil head is confirmed from the output intensity of a plurality of ultrasonic detectors placed at the corners of the display. This detection using ultrasonic waves is used for relatively small displays because the attenuation of ultrasonic waves is large.

(8 Problems to be Solved by the Invention) The functions of the conventional digitizer described above are as follows:
In both cases, detection mechanisms (LEDs, optical sensors, ultrasonic detectors, etc.) are disposed around the display, so they have the following problems.

■When the size of the display changes, the layout of the detection mechanism needs to be changed each time.

■If the display surface is curved, it may be necessary to install the detection mechanism by protruding it.

■In order to improve the accuracy of position specification, it is necessary to arrange detection mechanisms at a high density.

In addition to the above-mentioned problems, devices using ultrasonic waves have a problem in that they cannot be used for large-screen displays such as projection devices because the amount of attenuation of ultrasonic vibrations is large.

The present invention has been made in view of the problems existing in the prior art as described above, and is a rear projection type device equipped with a digitizer function that allows position specification regardless of external shape and screen size. The purpose is to realize a display device.

[Means to solve the problem]

A rear projection display device of the present invention is a rear projection display device including a transmission screen and a projection optical system that projects image light onto the rear surface of the transmission screen. An infrared light projection means for sequentially scanning and projecting in horizontal and vertical directions, an infrared sensor for detecting infrared light, and a projection optical system for projecting the image light are provided behind the transmission screen. A signal indicating the irradiation status of the infrared light projection means and the detection status of infrared light of the infrared sensor are respectively inputted, and when the infrared light is detected by the infrared sensor, the current The apparatus includes a control device that assumes that an instruction has been input to a predetermined location on the transmission screen onto which infrared rays are projected.

In this case, each of the projection optical system and the infrared light projection means is provided with a transmission type liquid crystal device whose transmitted light becomes image light and infrared light, and each illumination light illuminates each of these transmission type liquid crystal devices. may be visible light and infrared light that are separated by light generated by one light source being incident on a cold mirror, or image light and infrared light after passing through each transmission type liquid crystal device. Each of these may be incident on a dichroic mirror, combined, and projected onto a transmission screen via the same projection lens.

[Effect]

The infrared light that is scanned by the infrared light projection means and projected onto the transmissive screen is transmitted to the rear surface of the transmissive screen by pressing an infrared light reflecting member or the like against the front surface (viewer side) of the transmissive screen. It can be reflected towards. The reflected infrared light is detected by an infrared sensor, and it is detected that an instruction has been input at a predetermined location on the transmission screen to which the infrared light reflecting member -E is pressed.

Since both the above-mentioned infrared light detection means and infrared sensor are provided on the back of the transmissive screen, it is possible to specify the position of a predetermined point on the transmissive screen regardless of the external shape or size of the rear projection display device. .

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a light source for projection, which includes visible light and infrared light. 2 is a parabolic mirror for reflection, 3 is a cold mirror that reflects visible light and transmits infrared light, 4 and 5 are total reflection mirrors, 6 is a filter that adjusts the intensity of infrared light, and 7 is a projection mirror. 8 is a liquid crystal device for position detection that projects infrared light, 9 is a dichroic mirror that transmits visible light and reflects infrared light, 10 is a projection lens, 11 is a transmissive screen, 12 13 is an infrared sensor with a visible light removal filter attached to the tip of the optical sensor; 14 is an infrared sensor with an infrared reflective member attached to the tip;
1 is a head amplifier that receives an output signal from the infrared sensor 13 and amplifies it; 15 is a CPU that calculates the position of the light ben 12; and 16 is a light ben 12 that has been calculated by the CPU 15.
17 is a character/graphic signal generator that generates and outputs character and graphic signals from the position information; 18 is connected to an external video input terminal 22 into which a video signal from the outside is input; , a video synthesis device that combines the video signal and the position information of the light ben 12; 19 and 21 are LC drive circuits for modulating and scanning the liquid crystal devices 7 and 8; 20 is a LC drive circuit that synchronizes with external video input signals and This is a clock generation circuit that generates timing clock pulses when the device 7.8 and the CPU 15 operate.

As shown in FIG. 1, the cold mirror 3 and the total reflection mirror 5 are arranged in order on the optical path of the illumination light generated by the light source 1 so as to reflect the illumination light upward in the drawing. The dichroic mirror 9 is arranged so as to reflect each reflected light from the cold mirror 3 and the total reflection mirror 5 in the right direction in the drawing. The filter 6 is provided between the cold mirror 3 and the total reflection mirror 5, and the liquid crystal device 7 is provided between the total reflection mirror 4 and the dichroic mirror 9.
is set between. Further, the liquid crystal device 8 is provided between the total reflection mirror 5 and the dichroic mirror 9.

In this embodiment, the direct light emitted from the light source 1 and the light reflected by the parabolic mirror 2 are combined and the cold mirror 3
incident on . Of these, visible light is reflected by the cold mirror 3 and then reflected again by the total reflection mirror 4,
After passing through the liquid crystal device 7 modulated by the video signal output by the LC drive circuit 19, the dichroic mirror 9
, and is magnified by the projection lens 10 and displayed on the screen 1.
1 and forms an image. On the other hand, the infrared light emitted from the light source 1 and separated by the cold mirror 3 passes through the cold mirror 3, is attenuated into appropriate infrared light by the infrared attenuation filter 6, and is reflected by the total reflection mirror 5. After passing through a liquid crystal device 8 for infrared light modulation, which is subsequently subjected to sequential scanning modulation, it is reflected by a dichroic mirror 9, magnified by a projection lens 10 in the same way as the visible light described above, and projected onto a screen 1.
1 and forms an image.

As described above, in this embodiment, a projection optical system is configured by the light source 1, the cold mirror 3, the total reflection mirror 4, the liquid crystal device 7, and the dichroic mirror 9.
, a cold mirror 3, a filter 6, a total reflection mirror 5, a liquid crystal device 8, and a tichroic mirror 9 constitute an infrared light projection means.

Since the screen 11 is of a transmission type, the image formed on the screen 11 can be observed from the right side of FIG. 1, and the scanned infrared light is reflected at the tip of the light ben 12. Then, the reflected infrared light is detected by the infrared sensor 13.

FIG. 2(a) to FIG. 2(C) are diagrams for explaining a method of driving the liquid crystal device 8 for position detection in this embodiment.

FIG. 2(a) is a diagram showing the configuration of the liquid crystal device 8. As shown in FIG.

The liquid crystal device 8 has column electrodes Y, Y2.

..., a horizontal scanning section 8 that controls the voltage applied to Yn
1, and a vertical scanning section 82 that controls the voltage applied to the row electrodes X+,
A signal for modulating and scanning the liquid crystal device 8 outputted by the drive circuit 21 is sent to the liquid crystal device 8 and the CPU 15 as shown in FIG. 1, and in the liquid crystal device 8 as shown in FIG. is input to each of the horizontal scanning section 81 and the vertical scanning section 82. Depending on the content of this input signal, the horizontal scanning section 81 and the vertical scanning section 82
Column electrode Y as shown in Figure (b) and Figure 2 (C), respectively.
1 to Yn 1 A signal for driving the row electrodes x1 to xn is generated. Column electrodes 71 to 719 and row electrodes x1 to xn are driven by these signals to modulate and scan liquid crystal device 8. Therefore, on the screen 11,
As shown in FIG. 3, address-coded infrared light is sequentially projected.

Next, designation of a predetermined location on the screen 11 in this embodiment will be explained with reference to FIG. 1 again. The infrared light passing through the liquid crystal device 8 scanned as described above is reflected at the tip of the light ben 12, detected by the infrared sensor 13, and converted into an electrical signal. After this, the head amplifier 14 amplifies the signal to an appropriate signal level and sends it to the CPU 15.
is output to. The CPU 15 determines whether the position of the infrared reflection signal corresponds to the position on the screen 11 based on the output signal of the LC drive circuit 21, and stores this position in the memory 16.
to be memorized. In this way, information corresponding to the movement of the light ben 12 is stored in the memory 16. The information stored in the memory 16 is sent to the character/graphic signal generator 17 via the CPU 15 and converted into video signal data. This video signal data is combined with an external video signal input to an external video input terminal 22 in a video synthesis device 18, and then output to an LC drive circuit 19 that drives a liquid crystal device 7 for projection. As a result, the image data drawn by the light ben 12 is superimposed on the image projected on the screen 11. In this case, by displaying a specific area with characters, etc., and pressing down on that area with the light ben 12 (reflecting the infrared light of that area), functions such as erasing, rewriting, enlarging, and reducing the characters can be performed. It is possible to provide a so-called window function by programming.

FIG. 4 is a diagram showing the main part configuration of a second embodiment of the present invention.

This embodiment differs from the first embodiment shown in FIG. 1 only in the optical system. For this reason, only the optical system portion is shown in FIG. 4, and the same parts as in FIG. 1 are given the same numbers and their explanations are omitted.

This embodiment is intended to improve the utilization efficiency of the light source 1, and illuminates the liquid crystal device 7 by aligning the polarization components of the illumination light generated by the light source 1 to those that are effective as illumination light. In order to realize this, in the optical system of this embodiment, a polarization converter 41 is installed between the light source 1 and the cold mirror 3.
is provided, and a polarizing beam splitter 42 is used instead of the dichroic mirror 9.

The polarization converter 41 converts the incident undefined polarized light into linearly polarized light having a P (or S) polarization component. The polarizing beam splitter 42 transmits the P-polarized light component and reflects the S-polarized light component, and the surface facing away from the liquid crystal device 8 (the surface located above in FIG. 4) absorbs light. An absorbent layer 43 is provided.

The undefined polarized light emitted from the light source 1 is converted into P-polarized light by the polarization converter 41 and then enters the cold mirror 3 . The visible light component reflected by the cold mirror 3 is further reflected by the total reflection mirror 4 and illuminates a transmissive liquid crystal device 7 for brightness modulation. Depending on the modulation content of the liquid crystal 7, the transmitted light becomes a composite light of a P-polarized light component and an S-polarized light component, and enters the polarizing beam splitter 42. The S-polarized component of this modulated light is reflected by the polarization beam splitter 42 and absorbed by the light absorption layer 43. On the other hand, the P-polarized light component passes through the polarizing beam splitter 42 and is enlarged and projected onto the screen 11 by the projection lens 10. On the other hand, the P-polarized infrared light that exits the polarization converter 41 is sent to the cold mirror 3.
After passing through the filter 6, the light is adjusted to an appropriate level of infrared light.
The light is reflected by the total reflection mirror 5 and illuminates the liquid crystal device 8 for scanning infrared light. The liquid crystal technology 8 changes the phase of the incident light to λ
/2, and the emitted light becomes S-polarized light, enters the polarizing beam splitter 42, and is reflected in the direction of the screen 11.

As described above, in this embodiment, by aligning the illumination light of each liquid crystal device 7.8 to either P-polarized light or S-polarized light, which is effective as illumination light, the following effects are produced.

■The utilization efficiency of the light source is improved (approximately twice as much), making it possible to realize high-brightness projection display devices.

(2) Since the illumination light is linearly polarized light, there is no need for the polarizing plate that was conventionally provided on the incident side of the liquid crystal device to make the illumination light only have a linearly polarized component. This simplifies the structure of the liquid crystal device and facilitates its manufacture. Furthermore, since the heat generated in the conventional polarizing plate is eliminated, the margin against temperature rise of the liquid crystal device is greatly increased (about 6 times).

In each of the embodiments described below, in order to simplify the optical system, each illumination light that passed through each liquid crystal device 7 and 8 was explained as being combined by the dichroic mirror 9 or the polarizing beam splitter 42, but this In the invention, since the image light is not used for position detection, it is not necessarily necessary to combine these, and the configuration of the image optical system (for example, a liquid crystal type with other configurations or a CRT for projection) is not necessary. An optical system for position detection may be provided in parallel with an optical system for imaging, and each illumination light obtained by each optical system may be combined on the screen.

Further, the driving frequency of the liquid crystal device 8 for position detection does not need to be synchronized with the driving frequency of the liquid crystal device 7 for projection, and can be set according to the response speed of the liquid crystal device 8 and the usage status of the light ben 12. The degree of freedom is also high.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

In the device according to claim 1, since the infrared light projection means and the infrared sensor for detecting the specified position are provided on the back side of the transmission screen, the infrared light projection means and the infrared sensor for detecting the specified position are provided on the back side of the transmission screen, so that the infrared light projection means and the infrared sensor for detecting the designated position are provided on the back side of the transmission screen. In the device according to claim 2, there is an effect that the position can be specified immediately.
Since the image light and the infrared light are each generated by the same light source, in addition to the above effects, the optical system can be made more compact.

In the third aspect of the present invention, since the image light and the infrared light are combined and projected through the same projection lens, the optical system can be made more compact.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention, and FIGS. 2(a) to 2(C) each explain a method of driving a liquid crystal device 8 in the first embodiment. FIG. 2(a) is a diagram showing the configuration of the liquid crystal display 8, and FIG. 2(b) and FIG. 2(c) are respectively diagrams showing the configuration of the horizontal scanning section 8I in FIG. FIG.
A diagram showing a state in which infrared light is projected onto the screen 110 in the figure, and FIG. 4 is a diagram showing the main part configuration of a second embodiment of the present invention. 1... Light source, 2... Parabolic mirror, 3...
Cold mirror, 4.5... Total reflection mirror 601. Filter, 7.8...Liquid crystal device, 8,...
・Horizontal scanning section, 8□... Vertical scanning section, 9... Dichroic mirror 10... Projection lens, 11... Screen, 1
2... Light Ben, 13... Infrared sensor, 1
4... Head amplifier, 15... CPU, 16...
Memory, 17... Character/graphic signal generation device, 18... Image synthesis device, 19.21-... LC drive circuit, 20... Clock generation circuit, 41... Polarization converter, 42... - Polarizing beam splitter, 43... light absorption layer.

Claims (1)

[Claims] 1. A rear projection display device comprising a transmissive screen and a projection optical system that projects image light onto the rear surface of the transmissive screen, comprising: horizontally and horizontally projecting infrared light onto the transmissive screen; An infrared light projection means for sequentially scanning and projecting in a vertical direction, and an infrared sensor for detecting infrared light are provided behind the transmission screen together with a projection optical system for projecting the image light. Then, signals indicating the irradiation status of the infrared light projection means and the detection status of infrared light of the infrared sensor are respectively input, and when the infrared light is detected by the infrared sensor, the current infrared light is displayed by the infrared projection means. 1. A rear projection type display device comprising: a control device that assumes that an instruction has been input to a predetermined location of the transmissive screen on which the image is projected. 2. In the rear projection type display device according to claim 1, each of the projection optical system and the infrared light projection means is provided with a transmission type liquid crystal device whose transmitted light is image light and infrared light, and each of these A rear projection type display device in which each illumination light that illuminates a transmissive liquid crystal device is visible light and infrared light that are generated by one light source and are separated by being incident on a cold mirror. 3. In the rear projection display device according to claim 2, each of the image light and the infrared light after passing through each transmission type liquid crystal device is incident on a dichroic mirror and combined, and is then combined through the same projection lens. A rear projection display device that projects onto a transmissive screen.