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US 6,719,427 B2Granted
Display device, projection display apparatus, driving device for light modulator, and method for driving light modulator
AssigneeCanon Kabushiki Kaisha
InventorsYukihiko Sakashita, Akihiko Ouchi
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Abstract
A display device includes a light modulator used as an image forming unit and a projection optical system for projecting and displaying an image. In the display device, gradation is represented by varying the ON-time in the temporal axis during one frame period of the light modulator. The ON-time is used by at least three light components.
Claims7
A projection display apparatus comprising:
- a light modulator used as image forming means;
- and
- a projection optical system for projecting and displaying an image,
- wherein gradation is represented by varying ON-time in the temporal axis during one frame period of said light modulator, and
- the ON-time is used by at least three light components,
- wherein said three light components comprises
- a first light component to make the light reflect or transmit maximally,
- a second light component to make the light reflect or transmit minimally, and
- a third light component to make the light reflect or transmit intermediately, and wherein
- said light modulator is a reflective device including a micromirror, and said gradation is performed by controlling said micromirror to at least three reflection angles including a first reflection angle in which the amount of light reflection to the projection optical system is the maximum;
- a second reflection angle in which the amount of light reflection to the projection optical system is the minimum;
- and a third reflection angle between the first reflection angle and the second reflection angle in which the amount is between the amount for the first reflection angle and the amount for the second reflection angle.
9 more elements
A method for driving a light modulator, comprising the steps of:
- dividing one frame period of the light modulator into subframe periods which have different periods corresponding to each bit;
- performing gradation display by at least ternary digits in the light modulator during the minimum subframe period;
- performing binary gradation display during subframe periods other than the minimum subframe period;
- performing a first driving state for displaying white, a second driving state for displaying black, and a third driving state for gradation display between the white display and the black display, and
- setting the amount of light reflection in the third driving state to be small by a predetermined proportion to the amount of light reflection in the first driving state, wherein
- the third driving state is performed during the minimum subframe period so that the ternary digits can be performed, and
- the first and second states are performed during subframe periods other than the minimum subframe period.
4 more elements
A method for driving a light modulator, comprising the steps of:
- performing a first driving state for displaying white, a second driving state for displaying black, and a third driving state for gradation display between the white display and the black display;
- setting the amount of light reflection in the third driving state to be small by a predetermined proportion to the amount of light reflection in the first driving state,
- dividing one frame period of the light modulator into subframe periods which have different periods corresponding to each bit;
- allotting any one of the first driving state and the third driving state to each of the subframe periods;
- defining a time slot corresponding to the minimum subframe period as a unit time slot;
- and
- reducing the predetermined proportion the number of time slots in the subframe periods to which the first driving state is allotted, so as to reduce the total number of time slots in the one frame period,
- thereby making a unit time slot period, which is the one frame period divided by the reduced total number of time slots, longer than a unit time slot period, which is the one frame period divided by the unreduced total number of time slots.
5 more elements
Dependencies are inferred from the claim text.