Shading distortion correction circuit for facsimile equipment

Abstract

Abstract PURPOSE: To give correction to the distortion caused by the filter when the analog signal showing the shading is reloaded, by memorizing and holding concurrently the frequency corresponding to the fixed level of the period immediately before the shading properties period along with its frequency change. CONSTITUTION: The sequential reading is given to the manuscript based on clock signal ϕ 2 supplied via AND gates 22 and 23 through free-running scanning element 21 for reading of the manuscript. The signals read out are applied to amplifier 25 possessing the blind sector to set up the DC component of output V 3 . Then output V 3 is applied to voltage control oscillator 26 to draw out signal F produced by converting the voltage change of signal V 3 into the frequency change. This signal F containing the shading properties is stored in shift register 29 and then read out by the clock of gate 22 to be led out to LPF31 via monostable multivibrator 30. The output of LPF31 is applied to differential amplifier 35 which supplies the picture signals corresponding to each line of element 21 via switching element 32 drawing out the signal corresponding to the shading period. Thus the shading can be corrected. COPYRIGHT: (C)1980,JPO&Japio

Inventors

• 👤 Mitsugi Ikeda
• 👤 Koji Ueda
• 👤 Hideji Yanase

Bibliographic Details