Non-linear digital emphasis circuit

Patent 4668988 Issued on May 26, 1987. Estimated Expiration Date:

October 25, 2004. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Video recorder having means for maintaining constant the amplitude of the frequency-modulated signal
Patent #: 4193084
Issued on: 03/11/1980
Inventor: Yamagiwa , et al.

Non-linear emphasis circuit
Patent #: 4451746
Issued on: 05/29/1984
Inventor: Hirose , et al.

Video signal processing device including emphasis and/or de-emphasis circuit Patent #: 4570193
Issued on: 02/11/1986
Inventor: Yamashita

Inventors

Assignee

Sony Corporation

Application

No. 06/665417 filed on 10/25/1984

US Classes:

348/625, Transition or edge sharpeners333/14, AMPLITUDE COMPRESSION AND EXPANSION SYSTEMS (I.E., COMPANDERS)348/613, Complementary system (e.g., preemphasis - deemphasis)386/9, Signal amplitude level control708/270Function generation

Examiners

Primary: Britton, Howard W.
Assistant: Peng, John K.

International Classes

H04N 9/793 (20060101)
H04N 9/86 (20060101)
H04N 9/79 (20060101)
H04N 5/14 (20060101)
H04N 5/923 (20060101)

Abstract

A non-linear digital emphasis circuit for non-linearly emphasizing a high frequency component of an input digital video signal in accordance with an amplitude of the digital video signal. This emphasis circuit comprises: a digital filter for emphasizing the high frequency component of the digital video signal; and a memory in which a data conversion table to non-linearly compress the amplitude of the digital video signal is written and to which the digital video signal is supplied as an address input. The respective polarities of the address input of the memory and of the readout output therefrom are inverted by a polarity inverter in accordance with the polarity of the digital video signal. With this emphasis circuit, an error of the frequency characteristic and time and temperature changes thereof are not caused and no adjustment of the characteristic is needed. Also, this circuit can be formed as an integrated circuit by utilizing only digital circuits.