Computer graphics processing and selective visual display system – Display driving control circuitry – Light detection means
Reexamination Certificate
1998-09-16
2001-04-10
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Display driving control circuitry
Light detection means
C345S205000, C345S206000, C359S630000, C359S631000
Reexamination Certificate
active
06215481
ABSTRACT:
This application is based on applications Nos. H9-253169 and H10-013700 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display apparatus for providing pictures by scanning light emitted from a light source.
2. Description of the Prior Art
As displays, flat-panel picture display apparatuses such as liquid crystal displays and CRT displays are generally known. As a display apparatus capable of inexpensively providing high-definition pictures, a scanning picture display apparatus has been disclosed.
The scanning picture display apparatus is designed to display pictures to the viewer's eye by scanning light emitted from a light source. For example, Japanese Laid-open Patent Applications Nos. H4-100088 and H7-135623 disclose picture display apparatuses of this type. These apparatuses provide two-dimensional pictures by scanning in the horizontal and vertical directions light emitted from a point light source.
In order for a scanning picture display apparatus to provide stable pictures, it is a condition to perform stable light scanning. Vibration of a mirror is typically used as light scanning means. These apparatuses include means for controlling the amplitude and the speed of the vibration mirror so that stable light scanning is performed. In the conventional apparatuses, means for detecting the movement of the vibration mirror is provided and based on the result of the detection, the controlling means controls the vibration mirror.
FIG. 1
schematically shows the structure of an example of a scanning mirror having the detecting means. Reference numeral
32
represents the scanning mirror and reference numerals
31
and
33
represent the detecting means. Of these detecting means, the detecting means
31
is a light intercepting plate and the detecting means
33
is a photointerruptor. The scanning mirror
32
is held by a mirror holder
34
and vibrates by being driven by driving portion
35
. The light intercepting plate
31
operates in conjunction with the vibration of the scanning mirror
32
.
By the light intercepting plate
31
moving, a space
33
a
serving as the optical path of photoelectrons of the photointerruptor
33
is intercepted or not intercepted. Therefore, by detecting the voltage, the movement of the light intercepting plate
31
is determined, so that the movement of the scanning mirror
32
is detected. Based on the result of the detection, the controlling means controls driving portion
35
for driving the scanning mirror
32
.
In the scanning picture display apparatus, since pictures are provided to the viewer's eye by scanning light from a point light source, light having a higher intensity than the light provided by a flat-panel picture display apparatus is required to provide sufficiently bright pictures. However, when high-intensity light is emitted from a point light source, if scanning is stopped because of a failure in scanning means, high-intensity light will concentrate on one point on the viewer's eye, which can cause troubles to the viewer's eye. Therefore, in the conventional apparatus, it is impossible to emit light having sufficiently high intensity for making the provided pictures sufficiently bright for the viewer.
In order to detect the movement of the vibration mirror, the detecting means is provided on the vibration mirror. In this arrangement, the detecting means can impair the vibration of the mirror. In order to provide high-definition scanning pictures, it is necessary for the vibration frequency of the mirror to be high. However, the weight of the detecting means provided on the mirror limits the frequency.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a display apparatus for displaying stable high-definition pictures that are safe for the eye.
To achieve the above-mentioned object, a display apparatus of the present invention comprises: scanning means for scanning light emitted from a light source; detecting means for detecting whether scanning by the scanning means is normal or abnormal; and light intercepting means for intercepting light when the detecting means detects that the scanning is abnormal.
According to this structure, the light intercepting means intercepts the light when the scanning means malfunctions or breaks. As a result, it never occurs that light is continuously supplied onto one point on the viewer's eye.
Moreover, a display apparatus of the present invention comprises: a light source for emitting light modulated based on a video signal; scanning means for scanning the emitted light; light intercepting means for intercepting the emitted light; detecting means for detecting whether scanning by the scanning means is normal or abnormal; and controlling means for stopping light emission from the light source when the detecting means detects that the scanning is abnormal.
REFERENCES:
patent: 5115228 (1992-05-01), Harris et al.
patent: 5418546 (1995-05-01), Nakagakiuchi et al.
patent: 5467104 (1995-11-01), Furness, III et al.
patent: 5592189 (1997-01-01), Kuzunuki et al.
patent: 5596339 (1997-01-01), Furness, III et al.
patent: 5671076 (1997-09-01), Matsubara et al.
patent: 5712649 (1998-01-01), Tosaki
patent: 5742264 (1998-04-01), Inagaki et al.
patent: 5880888 (1999-03-01), Schoenmakers et al.
patent: H4-100088 (1992-04-01), None
patent: H7-135623 (1995-05-01), None
Ishibashi Kenji
Nagata Hideki
Tanijiri Yasushi
Burns Doane , Swecker, Mathis LLP
Hjerpe Richard
Minolta Co. , Ltd.
Nguyen Kimnhung
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