Automatic contrast control
阅读：441发布：2023-11-07
专利汇可以提供Automatic contrast control专利检索，专利查询，专利分析的服务。并且An automatic contrast control circuit for a color television receiver for stabilizing contrast level when switching between channels having different modulation levels or types of scene being televised. The control circuitry contemplates the provision of an added signal input to the automatic gain control (AGC) system of the receiver nominally providing an output control voltage responsive to the level of received carrier strength to selectively control the amplification levels of certain of the receiver''s initial amplifier stages. The automatic contrast control circuitry includes a storage device for developing an additional control potential at the cathode of the AGC amplifier and a voltage-dependent, variable impedance device, such as a transistor, connected in parallel with the storage device and coupled to a source of signals in the luminance channel of the receiver. Signals representative of the level of contrast variations in the luminance information are thereby applied to the input of the transistor so as to selectively control the conduction thereof and, in turn, the charge level maintained by the associated storage device.，下面是Automatic contrast control专利的具体信息内容。
1. In a television receiver including signal amplifiers and a video processing channel developing composite video signals having a first sync and blanking interval indicative of carrier strength level and clamped at a fixed reference potential and a second image interval being representative of luminance information, automatic contrast control circuitry, including in combination: gain control means including an amplifier device having an output and at least two input control electrodes, said output being coupled to selected ones of said signal amplifiers; means coupled to said gain control means for the selective gating on thereof during which an output control voltage is developed at said output and applied to said signal amplifiers; first circuit means coupled between the video processing channel and one of said gain control amplifier input electrodes for developing a first input signal responsive to amplitude excursions in the carrier strength level during the first interval of said signal source; and second circuit means coupled between the video processing channel and the other of said gain control amplifier input control electrodes for developing a second input signal responsive to the level of amplitude excursions in the luminance information during the second image interval of the composite video signals, said first and second input signals determining said output control voltage representative of both carrier strength and level of luminance information to selectively control the amplification of said selected signal amplifiers in response thereto.
2. Automatic contrast control circuitry in accordance with claim 1 wherein said second circuit means includes a storage device and fixed impedance means connected in parallel between said other amplifier input control electrode and a reference point, and means for charging said storage device to a predetermined level of substantially unidirectional potential at said one input control electrode, said second circuit means further including a voltage-dependent variable impedance means coupled between the video processing channel and said one input control electrode to provide a variable impedance path in parallel with said fixed impedance means, the instantaneous value of which in combination with said fixed impedance means determining the discharge rate of said storage device and in turn the level of said unidirectional potential.
3. Automatic contrast control circuitry in accordance with claim 1 wherein said gain control means is of the gated type and said amplifier device is a dual-section electron discharge device having pairs of separate anodes and suppressor electrodes, and common cathode, and control and screen electrodes, said gain control amplifier having one of said anodes coupled to said selected signal amplifiers, with the suppressor electrode associated with said one anode forming one of said amplifier input control electrodes and said common cathode forming the other of said amplifier input control electrodes.
4. Automatic contrast control circuitry in accordance with claim 2 wherein said voltage-dependent variable impedance means comprises a transistor having a base electrode coupled to the video processing channel, a collector electrode coupled to said one input control electrode and an emitter electrode coupled to said reference point through a limiting resistance.
5. Automatic contrast control circuitry in accordance with claim 2 wherein said storage device is a capacitor and wherein the means for the charging thereof includes the conduction of current through a portion of said gain control amplifier during a predetermined time interval of the composite video signal.
6. Automatic contrast control circuitry in accordance with claim 2 wherein said storage device and fixed impedance means are of selected values to form a substantially long RC time constant.
7. Automatic contrast control circuitry in accordance with claim 2 wherein said second circuit means further includes diode clamping means coupled between said one input control electrode of said gain control amplifier and a reference potential, and poled to conduct upon said storage device reaching a predetermined level of discharge so as to prevent overloading of said gain control amplifier device.
8. In a television receiver including signal amplifiers and a video processing channel developing composite video signals having a first sync and blanking interval clamped at a fixed reference potential and a second image interval representative of luminance information, automatic contrast control circuitry including in combination: gain control means including an amplifier device having at least one input and at least one output coupled to selected ones of said signal amplifiers; voltage supply means coupled to said gain control means for applying operating potential thereto; means including a storage device and fixed impedance means connected in parallel between said input and a reference point and further including means for charging said storage device to a predetermined level of substantially unidirectional potential at said input; and circuit means including a voltage-dependent variable impedance means coupled between the video processing channel and said input for providing a variable impedance path in parallel with said fixed impedance means, the instantaneous value of which in combination with said fixed impedance means determines the discharge rate of said storage device and in turn the level of said unidirectional potential in response to the level of amplitude excursions in luminance information during the second image interval of the composite video signals, said gain control amplifier deriving an output control voltage in response to said applied input signals to selectively control the amplification of said selected signal amplifiers.
| 标题 | 发布/更新时间 | 阅读量 |
|---|---|---|
| 可变波长光源和包括可变波长光源的装置 | 2020-05-08 | 92 |
| 在通信装置的接收链中使用的系统和方法 | 2020-05-11 | 464 |
| 无线通信系统及用于其中的回声消除的方法、装置和介质 | 2020-05-08 | 721 |
| 一种E波段带有矢量调制器的多通道接收机 | 2020-05-11 | 606 |
| 混合键合的图像传感器的电路和读取方法 | 2020-05-11 | 387 |
| 电阻电路和可变增益放大电路 | 2020-05-08 | 838 |
| 成像设备、成像系统和可移动体 | 2020-05-11 | 347 |
| 射频信号放大装置和射频前端模组 | 2020-05-08 | 97 |
| 增益调节模块、控制方法及植入式神经刺激系统 | 2020-05-11 | 734 |
| 一种可变增益放大器和生物信号处理芯片 | 2020-05-08 | 753 |
高效检索全球专利专利汇是专利免费检索,专利查询,专利分析-国家发明专利查询检索分析平台，是提供专利分析，专利查询，专利检索等数据服务功能的知识产权数据服务商。
我们的产品包含105个国家的1.26亿组数据，免费查、免费专利分析。
分析报告
专利汇分析报告产品可以对行业情报数据进行梳理分析，涉及维度包括行业专利基本状况分析、地域分析、技术分析、发明人分析、申请人分析、专利权人分析、失效分析、核心专利分析、法律分析、研发重点分析、企业专利处境分析、技术处境分析、专利寿命分析、企业定位分析、引证分析等超过60个分析角度，系统通过AI智能系统对图表进行解读，只需1分钟，一键生成行业专利分析报告。
QQ群二维码
意见反馈
意见反馈