galaxi digicolor 26 chassis ittsel
A multiple automatic brightness control system for a television receiver includes a first automatic brightness limiter (ABL) circuit that responds solely to relatively long-duration changes in brightness-producing current and a second ABL circuit that reacts to shorter-duration changes in brightness-producing current. Both ABL circuits have threshold levels below which they do not respond to changes in brightness-producing current. However, the threshold level of the second ABL circuit is higher than that of the first, allowing the second ABL circuit to respond more quickly but only to higher amplitude changes in brightness-producing current. The first ABL circuit is connected to the brightness current circuit to respond when the brightness current exceeds a first threshold level, generating a first control signal to limit the brightness current to this threshold. This first ABL circuit includes a first time constant circuit through which the control signal is applied to the brightness control means. The second ABL circuit is linked to the brightness current circuit to respond only when the brightness current exceeds a second threshold level, which is higher than the first threshold. It produces a second control signal to limit the brightness current to this second threshold. The second ABL circuit features a second time constant circuit with a lower time constant value than the first, allowing it to respond to control signal frequencies that are higher than the maximum frequency of the first control signal. The brightness current circuit contains a voltage divider connected to the brightness current source, with the first ABL circuit connected to one point on the divider and the second ABL circuit connected to another point, which is more positive relative to the first. Additionally, the system includes a transistor with its emitter connected to a point in the brightness current circuit, its base connected to a reference voltage source, and its collector connected to a brightness-controlling terminal. The invention also features a luminance circuit connected to the brightness-controlling terminal. The automatic brightness control circuit of the television receiver comprises a high voltage circuit that applies high voltage to the anode of the cathode ray tube, causing brightness current to flow between the anode and cathode electrodes.
The automatic brightness control system is designed to enhance the viewing experience by dynamically adjusting the brightness of the television display based on the ambient light conditions and the content being displayed. The first ABL circuit, which is sensitive to longer-duration brightness changes, ensures that gradual shifts in lighting do not cause abrupt changes in brightness, thereby preventing viewer discomfort. This circuit employs a time constant that effectively filters out rapid fluctuations, allowing for a smoother visual transition.
On the other hand, the second ABL circuit is engineered to respond to more immediate changes in brightness, specifically those that exceed a higher threshold. This rapid response capability is crucial for scenarios where quick adjustments are necessary, such as during scene transitions in films or sudden changes in lighting conditions. The design ensures that while the first ABL circuit manages slow changes, the second ABL circuit can react promptly to significant increases in brightness, thereby maintaining optimal visibility without overwhelming the viewer.
The use of a voltage divider in the brightness current circuit is instrumental in providing distinct reference points for each ABL circuit. This arrangement allows for precise control over the threshold levels, ensuring that the first ABL circuit can operate effectively at lower brightness levels while the second ABL circuit remains active for more intense brightness scenarios. The incorporation of transistors in the design enables efficient control of the brightness signal, facilitating the rapid switching required for the second ABL circuit to function effectively.
Overall, the automatic brightness control system represents a sophisticated approach to managing display brightness in television receivers, combining multiple circuits to achieve a balance between responsiveness and stability, ultimately enhancing the viewer's experience.A multiple automatic brightness control for a television receiver including a first automatic brightness limiter (ABL) circuit responsive only to relatively long duration changes in brightness-producing current and a second ABL circuit responsive to brightness-producing current changes of shorter duration than the first ABL circuit. Both ABL circu its have threshold levels below which they are not responsive to brightness-producing current changes, but the threshold level of the second ABL circuit is higher than that of the first so that, while the second ABL circuit responds more quickly than the first, it does so only for higher amplitude changes in the brightness-producing current. C. a first automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current in excess of a first threshold brightness current level for producing a first control signal to limit said brightness current to said first threshold level, said first automatic brightness limiter circuit comprising a first time constant circuit through which said first control signal is applied to said brightness control means; D.
a second automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current only in excess of a second threshold brightness current level higher than said first threshold level for producing a second control signal to limit said brightness current to said second threshold level, said second automatic brightness limiter circuit comprising a second time constant circuit having a lower time constant value than said first time constant circuit and through which said second control signal is applied to said brightness control means such that said brightness control means is responsive to second control signal frequencies higher than the maximum frequency of said first control signal; and in which said brightness current circuit includes: b. a voltage divider connected to said source of brightness current, said first automatic brightness limiter circuit being connected to a first connection point on said divider and said second automatic brightness limiter circuit being connected to a second connection point on said divider, said second point being positive relative to said first point.
B. a first automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current in excess of a first threshold brightness current level and to limit said brightness current to said first threshold level, said first automatic brightness limiter circuit comprising a first time constant circuit to limit the maximum frequency to which said first automatic brightness limiter circuit can respond to a first value; and C. a second automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current only in excess of a second threshold brightness current level higher than said first threshold level to limit said brightness current to said second threshold level, said second automatic brightness limiter circuit comprising a second time constant circuit having a lower time constant value than said first time constant circuit to be responsive to frequencies higher than said maximum frequency of said first time constant circuit, and further comprising a transistor having an emitter connected to a connection point in said brightness current circuit, a base connected to a source of reference voltage, and a collector connected to a brightness-controlling terminal.
3. The invention as defined in claim 2 comprising, in addition, a luminance circuit comprising said brightness-controlling terminal. 4. An automatic brightness control circuit of a television receiver comprising: C. a high voltage circuit for applying a high voltage to the anode of said cathode ray tube to cause brightness current to flow between said anode and cathode electrodes;
🔗 External reference
The automatic brightness control system is designed to enhance the viewing experience by dynamically adjusting the brightness of the television display based on the ambient light conditions and the content being displayed. The first ABL circuit, which is sensitive to longer-duration brightness changes, ensures that gradual shifts in lighting do not cause abrupt changes in brightness, thereby preventing viewer discomfort. This circuit employs a time constant that effectively filters out rapid fluctuations, allowing for a smoother visual transition.
On the other hand, the second ABL circuit is engineered to respond to more immediate changes in brightness, specifically those that exceed a higher threshold. This rapid response capability is crucial for scenarios where quick adjustments are necessary, such as during scene transitions in films or sudden changes in lighting conditions. The design ensures that while the first ABL circuit manages slow changes, the second ABL circuit can react promptly to significant increases in brightness, thereby maintaining optimal visibility without overwhelming the viewer.
The use of a voltage divider in the brightness current circuit is instrumental in providing distinct reference points for each ABL circuit. This arrangement allows for precise control over the threshold levels, ensuring that the first ABL circuit can operate effectively at lower brightness levels while the second ABL circuit remains active for more intense brightness scenarios. The incorporation of transistors in the design enables efficient control of the brightness signal, facilitating the rapid switching required for the second ABL circuit to function effectively.
Overall, the automatic brightness control system represents a sophisticated approach to managing display brightness in television receivers, combining multiple circuits to achieve a balance between responsiveness and stability, ultimately enhancing the viewer's experience.A multiple automatic brightness control for a television receiver including a first automatic brightness limiter (ABL) circuit responsive only to relatively long duration changes in brightness-producing current and a second ABL circuit responsive to brightness-producing current changes of shorter duration than the first ABL circuit. Both ABL circu its have threshold levels below which they are not responsive to brightness-producing current changes, but the threshold level of the second ABL circuit is higher than that of the first so that, while the second ABL circuit responds more quickly than the first, it does so only for higher amplitude changes in the brightness-producing current. C. a first automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current in excess of a first threshold brightness current level for producing a first control signal to limit said brightness current to said first threshold level, said first automatic brightness limiter circuit comprising a first time constant circuit through which said first control signal is applied to said brightness control means; D.
a second automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current only in excess of a second threshold brightness current level higher than said first threshold level for producing a second control signal to limit said brightness current to said second threshold level, said second automatic brightness limiter circuit comprising a second time constant circuit having a lower time constant value than said first time constant circuit and through which said second control signal is applied to said brightness control means such that said brightness control means is responsive to second control signal frequencies higher than the maximum frequency of said first control signal; and in which said brightness current circuit includes: b. a voltage divider connected to said source of brightness current, said first automatic brightness limiter circuit being connected to a first connection point on said divider and said second automatic brightness limiter circuit being connected to a second connection point on said divider, said second point being positive relative to said first point.
B. a first automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current in excess of a first threshold brightness current level and to limit said brightness current to said first threshold level, said first automatic brightness limiter circuit comprising a first time constant circuit to limit the maximum frequency to which said first automatic brightness limiter circuit can respond to a first value; and C. a second automatic brightness limiter circuit coupled to said brightness current circuit to respond to brightness current only in excess of a second threshold brightness current level higher than said first threshold level to limit said brightness current to said second threshold level, said second automatic brightness limiter circuit comprising a second time constant circuit having a lower time constant value than said first time constant circuit to be responsive to frequencies higher than said maximum frequency of said first time constant circuit, and further comprising a transistor having an emitter connected to a connection point in said brightness current circuit, a base connected to a source of reference voltage, and a collector connected to a brightness-controlling terminal.
3. The invention as defined in claim 2 comprising, in addition, a luminance circuit comprising said brightness-controlling terminal. 4. An automatic brightness control circuit of a television receiver comprising: C. a high voltage circuit for applying a high voltage to the anode of said cathode ray tube to cause brightness current to flow between said anode and cathode electrodes;
🔗 External reference
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