Image display apparatus with backlit display and method of driving the same
AssigneeCanon Kabushiki Kaisha
InventorsHidetoshi Suzuki, Ichiro Nomura, Tetsuya Kaneko, Naoto Nakamura
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Abstract
An image display apparatus includes a panel type light source including a plurality of cold-cathode devices arranged two-dimensionally on a substrate and a phosphor member contained in a same vacuum container for emitting visible light upon irradiation of electron beams by the cold-cathode devices. In addition, a transmission type optical modulation panel using the panel type light source as a back light source.
Claims26
An image display apparatus, comprising:
- a light source including a vacuum container containing (i) a plurality of cold-cathode devices arranged two-dimensionally on a substrate, said cold-cathode devices emitting electron beams, and (ii) a phosphor member within said container, said cold-cathode devices irradiating said phosphor member with the emitted electron beams, and said phosphor member emitting visible light when irradiated by the emitted electron beams;
- a transmission type optical modulation panel comprising a light valve arranged outside of said container, said light valve being illuminated with and modulating the visible light emitted by said light source;
- and
- a plurality of variable voltage sources connected to said plurality of cold cathode devices, wherein
- said light source comprises red, green and blue phosphor members for color display and further comprising electric feeding means for operating said cold-cathode devices for irradiating said red, green and blue phosphor members with electron beams, and wherein
- said cold-cathode devices for irradiating said red phosphor members with electron beams, said cold-cathode devices for irradiating said green phosphor members with electron beams and said cold-cathode devices for irradiating said blue phosphor members with electron beams are connected to said respective variable voltage sources capable of changing the amplitude of the applying voltage and/or the time period of the applying voltage.
A method of driving an image display apparatus having a light source including a vacuum container containing (i) a plurality of cold-cathode devices arranged two-dimensionally on a substrate, the cold-cathode devices emitting electron beams, and (ii) a phosphor member within the container, the cold-cathode devices irradiating the phosphor member with the emitted electron beams, and the phosphor member emitting visible light when irradiated by the emitted electron beams and a transmission type of optical modulation panel comprising a light valve and arranged outside of the vacuum container, said method comprising the steps of:
- applying a voltage to the plurality of cold-cathode devices to force them to emit electron beams;
- irradiating the phosphor member with the electron beams emitted from the plurality of cold-cathode devices to cause the phosphor member to emit visible light;
- illuminating the transmission type optical modulation panel from behind with the visible light from the irradiated phosphor member;
- driving the transmission type optical modulation panel according to picture signals;
- and
- controlling the color balance of a display screen to a desired color tone by applying a color tone control signal to the light source and modifying the color tone of light emitted from the light source according to the control signal,
- wherein the step of modifying the color tone of light emitted from the light source further comprises the step of independently modifying the drive signal being applied to the cold-cathode devices for irradiating red phosphor members, the drive signal being applied to the cold-cathode devices for irradiating green phosphor members and the drive signal being applied to the cold-cathode devices for irradiating blue phosphor members according to the control signal,
- and wherein the step of modifying the drive signals being applied to the cold-cathode devices further comprises the step of changing the amplitude of the voltage being applied to the plurality of cold-cathode devices and/or the time period of applying the voltage according to the control signal.
A method of driving an image display apparatus having a light source including a vacuum container containing (i) a plurality of cold-cathode devices arranged two-dimensionally on a substrate, the cold-cathode devices emitting electron beams, and (ii) a phosphor member within the container, the cold-cathode devices irradiating the phosphor member with the emitted electron beams, and the phosphor member emitting visible light when irradiated by the emitted electron beams and a transmission type of optical modulation panel comprising a light valve and arranged outside of the vacuum container, said method comprising the steps of:
- applying a voltage to the plurality of cold-cathode devices to force them to emit electron beams;
- irradiating the phosphor member with electron beams emitted from the plurality of cold-cathode devices to cause the phosphor member to emit visible light;
- illuminating the transmission type optical modulation panel from behind with the visible light from the irradiated phosphor member;
- driving the transmission type optical modulation panel according to picture signals;
- and
- controlling the maximum brightness of a display screen to a desired level by applying a maximum brightness control signal to the light source and modifying the brightness of light emitted from the light source according to the control signal, wherein
- modifying the brightness of light emitted from the light source further comprises the step of changing the amplitude of the voltage being applied to the plurality of cold-cathode devices and/or the time period of applying the voltage according to the control signal.
A method of driving an image display apparatus having a light source including a vacuum container containing (i) a plurality of cold-cathode devices arranged two-dimensionally on a substrate, the cold-cathode devices emitting electron beams, and (ii) a phosphor member within the container, the cold-cathode devices irradiating the phosphor member with the emitted electron beams, and the phosphor member emitting visible light when irradiated by the emitted electron beams and a transmission type of optical modulation panel comprising a light valve and arranged outside of the vacuum container, said method comprising the steps of:
- applying a voltage to the plurality of cold-cathode devices to force them to emit electron beams;
- irradiating the phosphor member with electron beams emitted from the plurality of cold-cathode devices to cause the phosphor member to emit visible light;
- illuminating the transmission type optical modulation panel from behind with the visible light from the irradiated phosphor member;
- driving the transmission type optical modulation panel according to picture signals;
- and
- controlling the maximum brightness of a display screen to a desired level by applying a maximum brightness control signal to the light source and modifying the brightness of light emitted from the light source according to the control signal, wherein
- modifying the brightness of light emitted from the light source further comprises a step of changing the amplitude of the voltage being applied to the phosphor members.
Dependencies are inferred from the claim text.