Patent US1464122A successfully refreshed from Google Patents.
Patent US4964719A successfully refreshed from Google Patents.
US4964719A
Expired / Lapsed
US
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Control method of brightness of screen used for projection display and control apparatus of the same
Assignee: Hitachi Ltd
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Filing: 1989-08-10
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Granted: 1990-10-23
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Expires: 2009-08-10
Abstract
Abstract Brightness of a screen is detected on the basis of a luminous flux projected from a light source to the screen. This detection signal is fed back and a set value of brightness of the screen is compared with the detection signal. The magnitude of input power to the light source is controlled so that the comparison value becomes zero.
Inventors
- 👤 Makoto Tachikawa
- 👤 Osamu Suzuki
- 👤 Tadahiko Hashimoto
- 👤 Kuniyuki Igari
- 👤 Ichirou Katsuyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:07
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3141; H04N9/315; H04N9/3155; G; G09; G09G; G09G3/00; G09G3/001; G09G3/002; H04N5/00; H04N5/74
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
A control method of brightness of a screen used for a projection display, comprising setting in advance a relation between the magnitude of an input power to be supplied to a light source, its supply time and brightness of said light source to a relation such that brightness becomes substantially constant; measuring actually the supply time of the input power to said light source; and controlling the magnitude of the input power on the basis of a relation which is set in advance by said setting so that brightness becomes substantially constant.
Claim 2
Dependent Claim
92 words
A control method of brightness of a screen used for a projection display, comprising setting in advance a relation between the magnitude of an input power to be supplied to a light source, its supply time and brightness of said light source to a relation such that brightness becomes substantially constant; measuring actually the supply time of the input power to said light source; and controlling the magnitude of the input power on the basis of a relation which is set in advance by said setting so that brightness becomes substantially constant.
Claim 3
Dependent Claim
136 words
A brightness control apparatus of a screen used for a projection display, comprising: a light source; a screen on which a luminous flux emitted from said light source is modulated and displayed as an image; time measurement means for actually measuring the supply time of input power to said light source; and input power control means to which the relation between the magnitude of the input power to be supplied to said light source, its supply time and brightness of said light source is set in advance in such a manner that said brightness becomes substantially constant, which receives a signal from said time measurement means and which controls the magnitude of said input power on the basis of said relation which is set in advance so that brightness of said light source becomes substantially constant.
Claim 4
Dependent Claim
136 words
A brightness control apparatus of a screen used for a projection display, comprising: a light source; a screen on which a luminous flux emitted from said light source is modulated and displayed as an image; time measurement means for actually measuring the supply time of input power to said light source; and input power control means to which the relation between the magnitude of the input power to be supplied to said light source, its supply time and brightness of said light source is set in advance in such a manner that said brightness becomes substantially constant, which receives a signal from said time measurement means and which controls the magnitude of said input power on the basis of said relation which is set in advance so that brightness of said light source becomes substantially constant.
Claim 5
Dependent Claim
36 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said input power control means includes further means for changing and regulating an input current to said light source.
Claim 6
Dependent Claim
62 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said input power control means includes change-over switches for connecting individually the input side of said light source to a plurality of terminals having mutually different application voltages and a switch for switching said change-over switches on receiving the signal from said time measurement means.
Claim 7
Dependent Claim
91 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said input power control means includes a function generator which is connected to said time measurement means and to which an inverse function of the correlation between the supply time of the input power to said light source and brightness of said light source is set, and a multiplier for regulating the magnitude of the input power on receiving the signal from said function generator, disposed between said light source and its power source.
Claim 8
Dependent Claim
80 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said input power control means includes a function generator which is connected to said time measurement means and to which an inverse function of a correlation between the supply time of the input power to said light source and brightness of said light source is set, and an amplifier which receives a signal from said function generator and regulates a power source voltage.
Claim 9
Dependent Claim
34 words
A brightness control apparatus of a screen used for a projection display according to claim 4, wherein said time measurement means detects a voltage applied to said light source and measures its supply time.
Claim 10
Dependent Claim
34 words
A brightness control apparatus of a screen used for a projection display according to claim 5, wherein said time measurement means detects a voltage applied to said light source and measures its supply time.
Claim 11
Dependent Claim
34 words
A brightness control apparatus of a screen used for a projection display according to claim 6, wherein said time measurement means detects a voltage applied to said light source and measures its supply time.
Claim 12
Dependent Claim
33 words
A brightness control apparatus of a screen used for a projection display according to claim 4, wherein said time measurement means measures an A.C. input to a D.C. amplifier for said light source.
Claim 13
Dependent Claim
33 words
A brightness control apparatus of a screen used for a projection display according to claim 5, wherein said time measurement means measures an A.C. input to a D.C. amplifier for said light source.
Claim 14
Dependent Claim
33 words
A brightness control apparatus of a screen used for a projection display according to claim 6, wherein said time measurement means measures an A.C. input to a D.C. amplifier for said light source.
Claim 15
Dependent Claim
49 words
A brightness control apparatus of a screen used for a projection display according to claim 2, which further includes an alarm which operates after the passage of a predetermined time from the arrival of the magnitude of the input power to said light source at a set maximum value.
Claim 16
Dependent Claim
29 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said brightness detection means comprises a brightness detector or an illumination detector.
Claim 17
Dependent Claim
37 words
A brightness control apparatus of a screen used for a projection display according to claim 2, wherein said light source comprises either one of a Xe lamp, an Ar lamp, a mercury lamp or a halogen lamp.
Claim 18
Dependent Claim
53 words
A brightness control apparatus for a screen used for a projection display according to claim 2, which further includes means for comparing a magnitude of an input power regulated by said input power control means with the actual input power supplied to said light source and regulating the magnitude of the input power.
Claim 19
Dependent Claim
142 words
A brightness control apparatus of a screen used for a projection display, comprising: a light source; a screen on which a luminous flux emitted from said light source is modulated and displayed as an image; brightness detection means for detecting brightness of said screen; and input power control means to which the actually measured value detected by said brightness detection means is fed back, which compares the actually measured value with a set value of brightness of said screen set in advance and which controls the magnitude of the input power to be supplied to said light source in such a direction that the difference between them becomes zero, which further includes an alarm which operates after the passage of a predetermined time from the arrival of the magnitude of the input power to said light source at a set maximum value.
Claim 20
Dependent Claim
142 words
A brightness control apparatus of a screen used for a projection display, comprising: a light source; a screen on which a luminous flux emitted from said light source is modulated and displayed as an image; brightness detection means for detecting brightness of said screen; and input power control means to which the actually measured value detected by said brightness detection means is fed back, which compares the actually measured value with a set value of brightness of said screen set in advance and which controls the magnitude of the input power to be supplied to said light source in such a direction that the difference between them becomes zero, which further includes an alarm which operates after the passage of a predetermined time from the arrival of the magnitude of the input power to said light source at a set maximum value.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-10-22 | 1994-04-23 | 1994-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-22 | 1998-04-23 | 1998-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-22 | 2002-04-23 | 2002-10-23 | $7700.00 | Window Closed / Lapsed |