Browse Prior Art Database

High Resolution Character Centering

IP.com Disclosure Number: IPCOM000076570D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 83K

Publishing Venue

IBM

Related People

Buettner, JA: AUTHOR [+3]

Abstract

Character centering circuitry determines the relative position of characters within the raster and passes signals to beam control for raster position correction, and to the central processing unit for character registration correction.

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High Resolution Character Centering

Character centering circuitry determines the relative position of characters within the raster and passes signals to beam control for raster position correction, and to the central processing unit for character registration correction.

Characters on document 11, Fig. 1, are raster scanned by the beam from cathode-ray tube 10 which is focused by lens 13. The light reflected from document 11 is collected by photomultiplier tube 12 and the raw video signal is passed to video quantizing circuits 15. Timing circuitry 20 provides signals for circuitry 15 and for entering the quantized video bits into shift register 25. Character height profile circuit 30 of Fig. 1, includes character profile register 31, shown in Fig. 2. Register 31 is a 32-bit shift register and data is entered therein via AND circuit 32 and OR circuit 33. The inputs to AND circuit 32 are connected to positions 32 and 64 of register 25. Position 32 of shift register 31 is also connected as an input to OR circuit 33. The reset terminal of register 31 is connected to receive MCR from MCR and segmentation circuitry 45 of Fig. 1. Register 31 is shifted by signals from timing 20 and is of the type as shown in the IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 7, No. 7, December, 1964, page 600-601. MCR (minimum character requirement) is a video condition indicating that a predetermined minimum amount of black video data has been detected.

The character profile in register 31 is examined by character position correction count and control circuitry 50 of Fig. 1. This circuit includes AND circuits 51 and 52, Fig. 2, for setting and resetting latch 53, respectively. The output of latch 53 is a Black Bit Advance signal gated by AND circuit 54. This signal is applied to OR circuit 55 and functions to advance character position counter 65. Counter 65 determines the relative position of the character profile within the 32 bit high raster. Circuitry is provided for controlling counter 65, to cause it to count up one bit for each shift register bit time that a black bit is encountered until bit time 17 is reached. Counter 65 is then counted down one bit each time that a black bit is encountered from bit time 17 until bit time 33. When the value in counter 65 reaches zero as the counter is being counted down, sign trigger 67 which had previously been set positive is switched. The state of trigger 67, i.e., positive or negative, indicates if the character is high or low within the raster. The count remaining in counter 65 at the end of trace or raster time, is equal to the amount the character is above or below the ideal center. Counter 65 is operated every trace time for which MCR is up, but its value is stored in Buss In register 90, Fig. 1, only when a Segmentation or Character End signal is generated by circuit 45.

The Black Bit Advance signal applied to OR circuit 55 is passed to condition AND circuits 57 and 58. AND circuit 57 places counter 65 in a c...