Patent Grant
7176890
1. Field of the Invention
The present invention relates to a projection-type display device, and, in particular, to a projection-type display device having a novel feature of improving a system of combining an image projected and an image drawn thereon by a user.
2. Description of the Related Art
Conventionally, generally, a projection-type display device is applied to a projector, a media board with a display device, a personal computer, etc., is used as a monitor for two or more persons in a meeting, a lecture, etc., or is used as a monitor, such as in a personal computer used individually.
Such a projection-type display device is demanded to have a feature such that letters/characters, and/or pictures may be drawn on a display device in a superimposing manner together with an image projected there, and, also, the thus-drawn letters/characters and/or pictures can be obtained as electronic data.
For this purpose, an art is proposed in which a position of a nib contacted on a display screen is detected, and is traced. However, in order to detect the position at which the nib contacts, it is necessary to provide a special pen with the nib. Furthermore, in order to add/erase a letter/character/picture, it is needed to appropriately change a screen operation mode. Thus, the whole system becomes expensive and operation becomes complex.
Further, another art is disclosed by Japanese laid-open patent application No. 3-43726 in which an image drawn by a nib or the like on a display screen is scanned by a line-type photo-sensor, and, the thus-detected image is printed out. However, as the line-type photo-sensor should have a size corresponding to the size of the screen, the scanner should be larger in the case the size of the screen is larger. In such a case, as the scanner mechanically scans the screen, a mechanism of moving the scanner also may be large-sized. Thus, the whole system may become bulky. Also, as the screen is scanned by the scanner mechanically, a considerable time is required to read the whole image present on the screen.
According to a media board disclosed in Japanese laid-open patent application No. 6-347898, while an image printed on a transparent sheet is displayed on a screen, it is possible to draw/write letters/characters/pictures thereon. Further, as a scanner scans the thus-drawn image, the scanned image can be easily printed out, as a hard copy. However, in this art, as the scanner mechanically scans the image present on the screen, the problems same as in the above-mentioned art may occur, i.e., the whole system may become bulky.
According to a so-called optical blackboard disclosed by Japanese laid-open patent application No. 8-160539, as a user points on a screen by a special pen, an image is projected thereon according to a locus along which the user has moved the pen on the screen through a function of a photo-sensing technology or a pressure-sensing technology. In this art, as an image is displayed on the screen as a result of the user moving the special pen on the screen and then the movement being detected by the system, the relatively complex system is needed merely for drawing an image on the screen by the user, in comparison to a case where a user draws an image directly on a screen with ink or the like by using a common ink-used pen as in a common whiteboard.
According to a media board disclosed by Japanese laid-open patent application No. 10-297166, an image drawn on a screen is read electronically, the read image data is combined with another image being projected on the screen. However, no specific configuration of how to read a drawn image is disclosed in the publication.
The present invention is directed to the above-mentioned problems, and, an object of the present invention is to provide a projection-type display device in which, as a writing surface on which a user draws/writes an image is made approximately coincident with an image projection surface, operativity is improved, the whole system is simplified, and, also, the cost needed can be effectively reduced.
Further, according to the present invention, a software program for controlling the above-mentioned projection-type display device from an external personal computer etc., is provided. Thereby, it is possible to provide the projection-type display device less costly.
According to the present invention, a projection surface is provided on which a predetermined projection image is displayed through projection; a writing surface is provided on which an image can be drawn directly in a superimposing manner with the projection image displayed on the projection surface; and a photography part is provided for photographing the image drawn on the writing surface by means of an image-pickup part comprising two-dimensionally-disposed pixels.
Thereby, as a user can draw any image such as letters/characters/pictures on the writing surface in a manner same as in a case of a common whiteboard or blackboard, and, thus, a user-friendly system can be provided. Further, as it is possible to draw an image on the writing surface superimposing manner with the projection image displayed on the projection surface, the drawn image and projection image are combined properly on the sight of the user. Accordingly, a high-operative system can be provided.
Further, as the drawn image is photographed through an image-pickup part having two-dimensionally disposed pixels (such as a so-called digital still camera), it is easy to read the drawn image rapidly, and, also, it is not necessary to prepare a large-sized configuration to read even a large-sized image drawn on a screen. Accordingly, the whole system can be effectively miniaturized, and, thus, it becomes less costly.
Other objects and further features of the present invention will become more apparent from the following detailed description when read in conjunction with the following accompanying drawings:
Preferred embodiments of the present invention will now be described. However, respective components, specific types thereof, combinations, shapes, relative spatial arrangements, and so forth thereof which will be described are merely examples, and the present invention is not limited thereto. Further, for the same components, the same reference numerals will be given throughout the respective embodiments.
In this projection-type display device, a user can write, by using a pen 2 for writing, letters/characters, images, etc. on a writing field 1. As for the pen 2 for writing, a generally sold marker used for writing onto a whiteboard, such as a common pen employing alcoholic ink, may be used. Further, the writing field (sheet) 1 is made of material such that an image projected on a transparent screen 6 (see
The projection-type display device is enclosed by a housing 3 such that, as shown in
The projector 4 projects an image onto the transparent screen 6 through a reflective mirror 5. The transparent screen 6 is provided inside with respect to the writing field 1. In this configuration, since the field 1 is transparent, the user can view the projected image through the writing field 1 from the outside.
Further, an image written/drawn onto the writing field 1 by the user can also be viewed from the inside of this projection-type display device through the transparent writing field 1 and the transparent screen 6. Therefore, the CCD camera 7 provided inside of the display device can take a picture of the image written/drawn on the writing field 1. In the first embodiment, the CCD camera 7 takes a picture of an image written on the writing field 1 also through the reflective mirror 5.
Furthermore, by a processing control part 8 (see
In addition, the projector 4, reflective mirror 5, and transparent screen 6 mainly act as a projection part, while the CCD camera 7, writing field 1 and reflective mirror 5 mainly act as a photography part. Further, the switches 11 mainly act as a mode selection part.
According to a basic feature of the projection-type display device described above, this display device is superior in terms of user interface. With the same feeling as in a common blackboard or whiteboard, the user can draw letters/characters, line drawings, etc. onto the writing field 1. Further, the user can change photography (picture taking) processing modes, described later, easily.
Further, according to the first embodiment, preferably, an image projected onto the transparent screen 6 and an image taken in from the writing field 1 can be used independently. For this purpose, preferably, the projection-type display device is configured such that the image projected and the image taken in are taken independently. Furthermore, preferably, the surface on which an image is projected (transparent screen 6) and a surface on which an image is drawn (writing field 1) are made approximately coincident. Thereby, a taken-in drawn image can be easily superimposed on a projected image through the sight of the user. Thereby, the projection-type display device excellent in operativity and functionality can be provided.
With reference to
In
Further, the processing control part 8 produces an image (combined image) in combination of an image displayed onto the projector 4 and an image (user-drawn image) drawn by the user and taken in by the CCD camera 7. Furthermore, the processing control part 8 also controls processing of storing the user-drawn image and the above-mentioned combined image in the storage part 10, and processing of outputting them to the outside through the input-and-output part 9.
The input-and-output part 9 performs processing of inputting, into the internal processing control part 8 and into the internal projector 4, image signals outputted from an external personal computer etc., and processing of outputting the user-drawn image and combined image output from the processing control part 8 to the outside. In addition, this input-and-output part 9 includes I/O interfaces, such as a USB (Universal Serial Bus) interface, an IEEE1394 interface, and a SCSI (Small Computer System Interface), and/or includes an interface with a video card in an external apparatus, such as a PC.
The switches 11 are used for controlling ON/OFF of the projector 4, input of user's instructions for taking a picture of user-drawn image by the CCD camera 7, and selection between two types of photography processing modes.
These two types of photography processing modes will now be described. The first photography processing mode is a mode of operation for extracting and acquiring only the above-mentioned user-drawn image, and a second photography processing mode is a mode of operation for acquiring the above-mentioned combined image in which the user-drawn image and projection image are combined. These two photography processing modes are executed as a result of the processing control part 8 reading a predetermined software program from the storage part 10, as shown in
As shown in
With reference to
Furthermore, the processing control part 8 causes the image extraction part 82 to extract a user-drawn image I4 from the reversal image I2. This extraction is achieved as a result of the reversal image I2 having a reference image I3 previously taken at a state in which nothing is drawn in the writing field 1 and then reversed between right and left thereof subtracted therefrom. Thereby, any images, other than the user-drawn image currently drawn by user, such as cracks or the like of the transparent screen 6, are removed. Then, the user-drawn image I4 is stored by the storage part 10, for example, or is output to the external apparatus through the input-and-output part 9.
Similarly operation in the second photography processing mode will now be described with reference to
As for the user-drawn image I4 and the projection image I5, correspondence therebetween is made by the processing control part 8. That is, the projection image projected when the user-drawn image is taken by the CCD camera 7 in response to the operation made onto the switches 11 is made to have a correspondence to this user-drawn image. For this purpose, the processing control part 8 stores the projection image I5 together with the user-drawn image I4 in a manner of making correspondence therebetween into the storage part 10. Thereby, it is possible to take these images together easily in future. Further, the combined image I6 is stored by the storage part 10, for example, or is output to the external apparatus through the input-and-output part 9.
Further, since the projector 4 and CCD camera 7 use the approximately same surface (the writing field 1 and transparent screen 6), as shown in
However, in the example shown in
Further, in case where the projector 4 is disposed on the center axis 60 of the writing field 1 as shown in
Furthermore, in the embodiment, projection of an image by the projector 4 may be interrupted when the user-drawn image is picked up by the CCD camera 7. Thereby, it can be prevented that the projection image becomes obstructive to the photography of the user-drawn image, and, thereby, the user-drawn image cannot be extracted properly. Further, in addition to this, the photographed image which also contains the projection image may be acquired by the CCD camera 7, and, then, the projection image may be subtracted from the photographed image (reversal image).
The storage part 10 mainly includes a recording part, and the input-and-output part 9 mainly includes an input part and an output part. The image projected by the projector 4 and the image photographed by the CCD camera 7 may be appropriately processed by an external personal computer, or the like. For this purpose, the storage part 10 which once stores the image and the input-and-output part 9 which transmits the data to the external personal computer are needed.
Further, the image projected by the projector 4 may be of image data processed by the external apparatus, or the photographed projection image itself. Therefore, the input-and-output part 9 is also needed. Thereby, a selected image can be recorded in the above-mentioned storage part 10 or it can be transmitted to the external apparatus through the above-mentioned input-and-output part 9, and, thus, it becomes easier to perform image data processing by using the external processing apparatus.
Operation of the processing control part 8 in the first embodiment will now be described with reference to
Then, the processing control part 8 produces the user-drawn image I4 or combined image I6 according to the process shown in
Thereby, the projection-type display device can easily acquire information input through handwriting/drawing by the user as image information.
In the above-described first embodiment, processing such as control of the projector 4, CCD camera 7, switches 11, reversal of a photographed image obtained by the CCD camera 7, image extraction, image combining, etc. is performed by the processing control part 8 provided inside of the projection-type display device. According to a second embodiment of the present invention, as will now be described, this processing is performed by an external apparatus, such as a personal computer, instead.
According to the second embodiment, as shown in
Thus, according to the second embodiment, the configuration of the projection-type display device is simplified, and, also, a predetermined software provides various control processing needed. Thereby, the projection-type display device can be provided at low cost.
Since the other configurations and operations are the same as those of the first embodiment, duplicated description is omitted.
According to the second embodiment, the function of the processing control part 8 in the first embodiment is achieved directly by the CPU (central processing unit) included in the personal computer 108.
A projection-type display device in a third embodiment of the present invention will now be described.
According to the above-mentioned first embodiment, when the light source in the projector 4 is turned off in order to prevent floodlighting of the projector 4 from being applied in photographing a user-drawn image formed on the writing field 1 by the CCD camera 7, a considerable time is taken for again starting up the floodlighting for image projection by the projector 4, and, also, the life of the power supply thereof may be shortened through repetitive turning on/off thereof. In order to avoid such a situation, as shown in
In the configuration of the third embodiment, the light-blocking plate 21 is removed and thus, the transparent screen 6 can have an image projected thereunto from the projector 4 at a time of image projection, as shown in
As described above, the first or second photography processing mode is the mode in which an image which a user draws onto the writing field 1 is photographed by the CCD camera 7. However, if a projection image formed by the projector 4 is present on the transparent screen 6, the user-drawn image formed on the writing field 1 may not be photographed clearly. This is because a halogen lamp is generally used as the light source of the projector 4, and, thus, it may be difficult to clearly photograph the user-drawn image superimposed on the projection image in terms of brightness and luminous energy.
Then, it is desirable at a time of the first or second photography processing mode to prevent the image from being projected by the projector 4. Since the light beam emitted by the projector 4 is thus blocked by the light-blocking plate 21 at a time of the first or second photography mode according to the third embodiment, the user-drawn image on the writing field 1 can be photographed independently and clearly.
Operation of the processing control part 8 according to the third embodiment will now be described with reference to
Then, the processing control part 8 produces the user-drawn image or combined image according to processing shown in
Then, after acquiring the photographed image in the step S204, the processing control part 8 drives the stepper motor 22 so that the light-blocking plate 21 may be removed and allows the projection image to be displayed on the transparent screen 6 (in a step S206).
Thus, according to the third embodiment, since the photographed image can be obtained in a condition in which the light beam from the projector 4 is prevented from reaching the transparent screen 6 without turning off of the light source of the projector 4, the life of the projector 4 can be prevented from being superfluously shortened.
Since the other configurations and operations are the same as those of the first embodiment, duplicated description is omitted.
The above-mentioned third embodiment may also be configured by utilizing a personal computer or the like together with software programs as the above-mentioned first embodiment is modified into the second embodiment, as in a fourth embodiment of the present invention.
A fifth embodiment of the present invention will now be described.
When photographing an image present on the writing field 1 by the CCD camera 7, the resolution poses a problem. In order to increase the resolution in photography by the CCD camera 7, according to the fifth embodiment, pixel shifting function is applied. Thereby, the writing field 1 is photographed twice, and, at this time, the CCD 31 shown in
In the example shown in
The thus-obtained two pixel-shifted photographed images are input into the processing control part 8, and are combined together. Specifically, the combined image is obtained as a result of the pixels on the two images are arranged alternately one by one. According to the fifth embodiment, it is possible to effectively improve the resolution of the photographed image without increasing the pixels of the CCD 31 itself.
However, the number of pixels by which the shift is made and the direction of the shift are not limited. For example, the writing field 1 may be divided into division areas, and, each division area is photographed by the CCD camera. 7 by shifting the photography area of the camera 7 as mentioned above. Further, a user may select whether or not such shift function is applied, through the switches 11.
Generally many electric charge accumulation type CCD elements are used in the CCD camera 7. Many pixels are regularly arranged by unit area, and the CCD element accumulates the electric charge according to luminous energy irradiated there, and carries out photoelectric transform. Therefore, when it shifts by 1 pixel, a photograph is taken and the image data is combined afterwards when photographing a fixed area twice, it is possible to obtain a photograph same as that obtained by the double recording density. According to the fifth embodiment, for this reason, the resolution of the photographed image is improved twice. Further, by employing the piezoelectric device called a piezoelectric vibrator, it is possible to shift the CCD precisely by one pixel as the piezoelectric device has a mono-crystal formation and vibrates at a peculiar pitch as well-known.
Operation of the processing control part 8 according to the fifth embodiment will now be described with reference to
Then, the processing control part 8 moves the CCD 31 through the piezoelectric device drive circuit 33 by 1 pixel by means of the piezoelectric device 32 (in a step S305), and then controls the CCD camera 7 to take a photograph similarly (in a step S306), and acquires the thus-photographed image (in a step S307). Then, when the two photographed images shifted by 1 pixel are thus acquired, the processing control part 8 returns the CCD 31 to the original position by returning the piezoelectric device 32 to the original state through the piezoelectric device drive circuit 33 (in a step S308).
Then, the processing control part 8 combines the thus-obtained two photographed images (in a step S309). Then, the processing control part 8 produces the user-drawn image or combined image according to processing shown in
Then, after acquiring the photographed image in the step S307, the processing control part 8 drives the stepper motor 22 so that the light-blocking plate 21 may be removed (in a step S311).
In addition, the user-drawn image or the combined image generated by this is stored as mentioned above in the storage part 10, or is output to the external apparatus from the input-and-output part 9.
Accordingly, it is possible to obtain high-resolution image without increasing the physical number of pixels on the CCD 31. Since the other configurations and operations are the same as those according to the third embodiment, duplicated description is omitted.
The above-mentioned fifth embodiment may also be configured by utilizing a personal computer or the like together with software programs as the above-mentioned first embodiment is modified into the second embodiment, as in a sixth embodiment of the present invention.
A seventh embodiment of the present invention will now be described.
Generally, the resolution of an image is determined by a mutual relationship between the photography area and number of pixels of a CCD camera used. That is, when photographing a same area, resolution becomes higher as the area photographed is smaller. According to the seventh embodiment, since the above-mentioned writing field 1 is divided into the four areas, and the respective areas are photographed simultaneously by the four CCD cameras, the resolution of an image taken by each CCD camera can be made higher accordingly.
Further, according to the seventh embodiment, whether or not such a dividing photography manner is applied may be preferably determined by a user according to an intention of the user and/or an image formed on the writing field 1. Thereby, when the user-drawn image is a relatively simple one, and, or when the user does not wish such a dividing photography operation for some reasons, the dividing photography manner may not be applied, and a normal photography such that merely the full area or a predetermined area of the writing field 1 is photographed by the single CCD camera 7 is applied.
Furthermore, more preferably in terms of functions, the number of divisions in a case of the dividing photography may be determined by a user. Instructions as to whether or not the dividing photography mode is selected, and the number of division therein may be input through the switches 11. According to the seventh embodiment, operativity and functionality are improved.
Operation of the processing control part 8 according to the seventh embodiment will now be described with reference to
When instructions for the dividing photography have not been input in the step S403 (No in the step S403), the processing control part 8 sends instructions to the CCD camera of the CCD cameras 7A through 7D which can photograph the entire area of the writing field 1 (for example, a configuration is made such that the CCD camera 7A can do so) (in a step S404), and acquires the photographed image therethrough (in a step S405).
On the other hand, when instructions for the dividing photography have been input in the step S403 (Yes in the step S403), the processing control part 8 sends instructions to CCD cameras (any ones of those 7A through 7D) corresponding to the number of photography area divisions, specific photography areas, and so forth according to the instructions (Step S406), and acquires all the photographed images thus taken (in a step S407).
Further, the processing control part 8 combines these photographed images acquired according to a predetermined arrangement of the photography areas on the CCD cameras 7, and thus produces one combined photographed image (in a step S408).
Then, the processing control part 8 produces the user-drawn image or combined image according to processing shown in
Then, after acquiring the photographed image in the step S405 or S407, the processing control part 8 drives the stepper motor 22 so that the light-blocking plate 21 may be removed (in a step S410).
In addition, the user-drawn image or the combined image generated is stored as mentioned above in the storage part 10, or is output to the external apparatus from the input-and-output part 9.
Thereby, all or a part of the user-drawn image is acquirable in the resolution suitable for the demand of the user. Since the other configurations and operations are the same as those of the third embodiment, duplicated description is omitted.
The above-mentioned seventh embodiment may also be configured by utilizing a personal computer or the like together with software programs as the above-mentioned first embodiment is modified into the second embodiment. However, in this case, the CCD driver 1081 in the personal computer 108 is configured such that the driving control of the plurality of CCD cameras (7A through 7D) can be carried out thereby.
An eighth embodiment of the present invention will now be described.
In the eighth embodiment, a photography part 51 having pan/tilt functions performs photography on the writing field 1.
A user may give instructions to the projection-type display device to indicate a desired part of the writing field 1 by operating the photography part 51 using some of the switches 11. At this time, the projector 4 displays a currently set photography area of the CCD camera 7 on the transparent screen 6, as shown in
Based on user' instructions from the switches 11, the processing control part 8 performs control of the photography part 51. Further, in case high resolution photography is performed, the shaking mechanism 52 may be used. Namely, the writing field 1 is divided and photographed by a part-by-part manner, the thus-obtained partial photographed images are combined/collected/joined so that a high-resolution photography image is obtained. This dividing photography is achieved by appropriately controlling the optical axis of the CCD camera 7 through the above-mentioned tilt and pan functions of the shaking mechanism 52. The user can select either the dividing photography mode or the normal mode in which a photography image is obtained through a single photography operation without dividing the writing field 1, by using the switches 11. Further, the user may also select the number of divisions of the writing field 1 in the case of dividing photography mode, also through the switches 11.
The dividing photography is achieved by using the plurality of CCD cameras 7A through 7D according to the above-mentioned seventh embodiment, which needs costs for the number of CCD cameras. In contrast thereto, according to the eighth embodiment, only the single CCD camera 7 does the same through changing the optical axis thereof appropriately, which thus needs less costs. Thus, according to the eighth embodiment, the projection-type display device excellent in operativity and functionality can be provided at low costs.
Furthermore, this projection-type display device in the eighth embodiment is configured such that a storage area in the storage part 10 may be determined according to the angle of the CCD camera 7 in connection with the operation of the shaking mechanism 52.
Further, since the other configurations and operations are the same as those of the seventh embodiment, duplicated description is omitted.
A ninth embodiment of the present invention will now be described.
Thereby, since the writing field 1 is illuminated from the side opposite to the projector 4, the efficiency of lighting is improved, and a photographed image becomes brighter. However, if the light from the lighting 54 is irradiated directly to the user, the user's visibility may be degraded accordingly. Then, in this embodiment, a lampshade 55 is provided such that the light from the lighting 54 may be prevented from directly irradiating the user. The other configurations and operations of the ninth embodiment are the same as those of the first embodiment, and duplicated description is omitted.
A tenth embodiment of the present invention will now be described.
Therefore, it is necessary to locate the lighting 54 out of the path of the light beam 41 from the projector 4 toward the transparent screen 6. Thus, since the lighting 55 illuminating the writing field 1 from the side of the projector 4 is located out of the path of the light beam 41 from the projector 4 according to the present embodiment, it does not have a bad influence on the projection image from the projector 4, and, also, the entire display device can be made smaller.
However, if the light from the lighting 54 irradiated directly the CCD camera 7, a photographed image taken by the CCD camera 7 would fade white. Then, according to the tenth embodiment, a lampshade 55 is provided in such a manner that the light from the lighting 54 may not directly irradiate the CCD camera 7.
The other configurations and operations of the tenth embodiment are same as those of the first embodiment, the duplicated description is omitted.
An eleventh embodiment of the present invention will now be described.
The writing field 1 should be illuminated brightly as much as possible, and also, the illumination should be made uniformly. Therefore, according to the eleventh embodiment, the lightings 56 and 57 are provided in symmetrical positions with respect to an axis 58 corresponding to the optical axis of the projector 4, thereby the homogeneity in brightness on the writing field 1 being improved effectively.
Thus, according to the eleventh embodiment, since on the side of the projector 4, the lightings 56 and 57 are provided for illuminating the writing field 1 approximately symmetrically with respect to the axis 58 corresponding to the optical axis of the projector 4, it does not have a bad influence on a projection image from the projector 4, brightness thereon becomes uniform, and the unevenness on the image is eliminated.
However, if the light from the lightings 56 and 57 irradiated directly the CCD camera 7, a photographed image taken by the CCD camera 7 would fade white accordingly. Then, according to the-eleventh embodiment, lampshades 55 are provided such that the light from the lightings 56 and 57 may not directly irradiate the CCD camera 7.
The other configurations and operations are same as those of the first embodiment, and duplicated description is omitted.
A twelfth embodiment of the present invention will now be described.
When using the projection-type display device as a simple display device, the dispersion sheet 23 may be removed to a position such that it may not be obstructive by a winding mechanism. That is, the dispersion sheet 23 can be removed/inserted through pulling members 25 and a winding roller 24, as shown in the figure. It is noted that, in this embodiment, a configuration is made such that the writing field 1 and transparent screen 6 are pressed onto one another forcibly. Therefore, while being pressed by both of the writing field 1 and transparent screen 6, the dispersion sheet 23 is pulled out/inserted in by the pulling members 25/winding roller 24. Thereby, the dispersion sheet 23 is prevented from twisting or bending between the writing field 1 and transparent screen 6, but can be maintained in a plane state.
According to the twelfth embodiment, the opaque white dispersion sheet 23 is provided on the rear side of the writing field 1 with respect to the user. Thus, the writing field 1 can also be used as a whiteboard satisfactorily, and thus, a usage scope of the projection-type display device can be effectively widened.
Since the other configurations and operations of the twelfth embodiment are the same as those of the first embodiment, duplicated description is omitted.
A thirteenth embodiment of the present invention will now be described.
Further, the dispersion sheet 23 (transparent area 62 is included therein) has top and bottom portions thereof wound by the rolling rollers 24, respectively, and can be moved arbitrarily through a winding crank handle 61 connected with the lower winding roller 24, as shown in the figures. That is, the winding crank handle 61 provided outside of the display device is connected with a rotation shaft of the lower winding roller 24, as in the above-mentioned twelfth embodiment. Furthermore, the upper and lower rolling rollers 24 are connected by a timing belt together such that these rollers rotate in synchronization with one another in the same direction. Thereby, the dispersion sheet 23 is rolled without right-and-left unbalance, and it becomes possible to move the transparent area 62 up and down arbitrarily. In addition, the above-mentioned transparent area 62 is thus movable upward or downward so that this area 62 may not overlap the writing field 1 at all, as shown in
According to the thirteenth embodiment, the opaque white dispersion sheet 23 can be inserted on the rear surface of the writing field 1 with respect to the position of the user as mentioned above, and thus, this display device can be satisfactorily used as a whiteboard and thus, the usage scope of the projection-type display device can be effectively widened.
Since the other configurations and operations are the same as those of the first embodiment, duplicated description is omitted.
A fourteenth embodiment of the present invention will now be described. According to any of the above-mentioned embodiments, in case the writing field 1 does not have a sufficiently structural strength such as to maintain the plane state during a drawing/writing operation performed by a user thereon with the pen 2 as shown in
However, it is also possible that, as shown in
Since the other configurations and operations are the same as those of the first embodiment, duplicated description is omitted.
Further, the present invention is not limited to the above-described embodiments, and variations and modifications may be made without departing from the scope of the present invention.
The present application is based on Japanese priority applications. Nos. 2001-059321 and 2001-255119, filed on Mar. 2, 2001 and Aug. 24, 2001, respectively, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001-059321 | Mar 2001 | JP | national |
| 2001-255119 | Aug 2001 | JP | national |
| 2002-050541 | Feb 2002 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20020130979 A1 | Sep 2002 | US |
