초록 ▼

An automatic gain control (AGC) system controls a receiver having multiple amplifier stages with near constant compression. The AGC system controls gain, and thus compression, of each stage employing information generated by the other stages to generate feedback signals at a system level. A central

An automatic gain control (AGC) system controls a receiver having multiple amplifier stages with near constant compression. The AGC system controls gain, and thus compression, of each stage employing information generated by the other stages to generate feedback signals at a system level. A central controller uses threshold detection to monitor signal power at each stage of the receiver signal path as well as overall signal gain. Based on these various signal power measurements, the central controller adjusts signal gain of the input to one or more stages, while maintaining overall signal gain for a constant output signal level. The AGC function may be implemented by switching the gain of each stage's variable amplifier in discrete steps in discrete steps, with the step size being coarser for stages closer to the input signal than those closer to the final output baseband signal. Monitoring power of the signal at these points as the signal passes through the series chain of components may also allow for resolution of the desired signal from unwanted interferer signals coincident with the desired signal. Resolution of the desired signal at each stage may further allow for refinement of the gain settings within the receiver. System level feedback may enhance stability and provides the following flexibilities. First, attenuation of the signal as it passes through, for example, the RF/IF receiver is done in discrete steps. Second, the circuit may be relatively easy to implement in integrated circuit (IC) technology. Third, the present invention allows for constant compression, in turn allowing processing of relatively high-level, input signals.

대표청구항 ▼

An automatic gain control (AGC) system controls a receiver having multiple amplifier stages with near constant compression. The AGC system controls gain, and thus compression, of each stage employing information generated by the other stages to generate feedback signals at a system level. A central

An automatic gain control (AGC) system controls a receiver having multiple amplifier stages with near constant compression. The AGC system controls gain, and thus compression, of each stage employing information generated by the other stages to generate feedback signals at a system level. A central controller uses threshold detection to monitor signal power at each stage of the receiver signal path as well as overall signal gain. Based on these various signal power measurements, the central controller adjusts signal gain of the input to one or more stages, while maintaining overall signal gain for a constant output signal level. The AGC function may be implemented by switching the gain of each stage's variable amplifier in discrete steps in discrete steps, with the step size being coarser for stages closer to the input signal than those closer to the final output baseband signal. Monitoring power of the signal at these points as the signal passes through the series chain of components may also allow for resolution of the desired signal from unwanted interferer signals coincident with the desired signal. Resolution of the desired signal at each stage may further allow for refinement of the gain settings within the receiver. System level feedback may enhance stability and provides the following flexibilities. First, attenuation of the signal as it passes through, for example, the RF/IF receiver is done in discrete steps. Second, the circuit may be relatively easy to implement in integrated circuit (IC) technology. Third, the present invention allows for constant compression, in turn allowing processing of relatively high-level, input signals. to each other, as seen at a position where said image carrier and said charging member contact each other. 4. An apparatus as claimed in claim 3, wherein said magnetic particles for charging each have a conductive surface layer. 5. An apparatus as claimed in claim 4, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 6. An apparatus as claimed in claim 3, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 7. An apparatus as claimed in claim 2, wherein said magnetic particles for charging each have a conductive surface layer. 8. An apparatus as claimed in claim 7, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 9. An apparatus as claimed in claim 2, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 10. An apparatus as claimed in claim 1, wherein said magnetic particles for charging each have a conductive surface layer. 11. An apparatus as claimed in claim 10, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 12. An apparatus as claimed in claim 1, wherein the developing unit bifunctions as a cleaning unit for collecting the toner left on said image carrier after a transfer of said toner image from said image carrier to a recording medium. 13. An image forming apparatus comprising: image carrier means for carrying an image and comprising a conductive support, at least a photoconductive layer formed on said conductive support, and a surface protection layer formed on said photoconductive layer and including a charge injection layer; charging means for charging said image carrier means in contact with said surface protection layer when applied with a voltage; and developing means for developing a latent image formed on said image carrier means with toner to thereby produce a corresponding toner image, wherein said surface protection layer has a diamond-like carbon structure or an amorphous structure containing hydrogen, wherein said developing means develops the latent image with a magnet brush formed by magnetic particles for development, wherein said charging means comprises magnetic particles for charging having a mean particle size smaller than a mean particle size of said magnetic particles for development, wherein said surface protection layer has a volume resistance of 109Ω·cm to 1012Ω·cm and a Knoop hardness of 400 kg/mm2or greater, and wherein a light transmission of the surface protective layer is 50% or more of a wavelength of light used for exposing the image carrier means. 14. An apparatus as claimed in claim 13, wherein said image carrier means and said charging means contact each other, and each moves at a particular linear velocity. 15. An apparatus as claimed in claim 14, wherein said image carrier means and said charging means move in opposite directions to each other, as seen at a position where said image carrier means and said charging means contact each other. 16. An apparatus as claimed in claim 15, wherein said magnetic particles for charging each have a conductive surface layer. 17. An apparatus as claimed in claim 16, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium. 18. An apparatus as clai med in claim 15, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium. 19. An apparatus as claimed in claim 14, wherein said magnetic particles for charging each have a conductive surface layer. 20. An apparatus as claimed in claim 19, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium. 21. An apparatus as claimed in claim 14, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium. 22. An apparatus as claimed in claim 13, wherein said magnetic particles for charging each have a conductive surface layer. 23. An apparatus as claimed in claim 22, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium. 24. An apparatus as claimed in claim 13, wherein said developing means bifunctions as cleaning means for collecting the toner left on said image carrier means after a transfer of said toner image from said image carrier means to a recording medium.