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INTRODUCTION. Numeric as well as alphanumeric displays are popularly used in several places such as business machines, hand-held instruments,.
Beg & Ahmed: Two Simple Bar Matrix Display Formats for Alphanumeric English Characters

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TWO SIMPLE BAR MATRIX DISPLAY FORMATS FOR ALPHANUMERIC ENGLISH CHARACTERS M. Salim Beg Dept. Electronic & Elect Engg. University of Technology Loughborough, Leics., LE1 1 3TU U.K.

Wasim Ahmed Dept. of Electronic Engg. Aligarh Muslim University Aligarh 202002 India.

ABSTRACT

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In this paper two novel and very simple bar matrix layouts having 9 segments (plus a dot) and 10 segments (PIUS 2 dots) respectively for displaying English alphanumeric characters are proposed. The proposed displays involve simpler interfacing circuits and consume lesser power compared to the 14segment (having 14 segments plus 2 dots) and 16-segment (having 16 segments plus 2 dots) displays being presently used.

Over the past few years, the need for alphanumeric displays has grown very rapidly because of the development of new systems using microprocessors. 7-segment displays are generally used for numeric characters only because they are not able to display all the alphanumeric characters. For alphanumeric characters, 14segment and 16-segment bar matrix display formats are used. Alphanumeric display systems using these 14-segment and 16segment bar matrices are commercially manufactured and are available in the market [1,2].

INTRODUCTION Numeric as well as alphanumeric displays are popularly used in several places such as business machines, hand-held instruments, automotive instrument panels, computer terminals and general purpose display boards. Dot matrix displays (e.g. 5x7 matrix involving 35 elements) and bar matrix displays (e.g. 7-segment, 14-segment and 16-segment) are commonly used. Although dot matrix approach can generate characters of better shape, bar matrix approach is more often preferred in instrumentation and many other application because of it's simplicity and smaller power

Contributed Paper Manuscript received April 11, 1988.

In this paper two novel bar matrix formats containing 9 segments and 10 segments each are presented which are much simpler than the ones commercially available these days. Since the proposed formats contain smaller number of segments, they will involve simpler electronics and will consume less power as compared to 14- and 16-segment displays. PROPOSED LAYOUTS The proposed bar matrix layouts along with their element identifications are shown in

0098 3063/88/0200 0357$01 .OO @ 1988 IEEE

IEEE Transactions on Consumer Electronics, Vol. 34, No. 2, MAY 1988

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Figs. l(a) and l(b) The first one has 9 segments and a dot (giving a total of 10 elements) while the second one has 10 segments and 2 dots (giving a total of 12 elements). The layouts are specially designed so that with selective unblanking of various elements all the numeric and alphanumeric English characters as well as special symbols can be displayed. Both the layouts can display the complete set of 64 characters which can be addressed by 6 bit ASCII code input (just like the commonly used 14-segment and 16segment displays). The resultant displays for the various characters and special symbols along with their codes for the two layouts are shown in Figs. 2(a) and 2(b) respectively. The proposed display schemes offer a great potential in digital display and instrumentation applications where cost and complexity is more important than the beauty of the characters. IMPLEMENTATION OF THE DISPLAY SYSTEM The proposed layouts can be implemented in the form of display modules using LEDs or LCDs which could easily be manufactured. 6 bit ASCII code input is given to the character address decoder which has 64 word lines at it's output (corresponding to the total number of 64 characters to be displayed). The outputs of the character address decoder go to a ROM code converter of appropriate dimensions. A ROM code converter of 640 bits (64 x 10) capacity will be required for the layout of Fig. l(a) having 10 elements ( 9 segments and a dot). On the other hand ROM code converter of 768 bits ( 6 4 x 12) capacity will be required for the layout of

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Fig.1 Proposed character layouts with element identification (a) 9-segment (plus 1 dot) (b) 10-segment (plus 2 dots) Fig. l(b) having 12 elements (10 segments and 2 dots). 10 and 12 bit PROMS are available and they can be programed for the element unblanking according to the ASCII code set given in Fig. 2. Detailed circuits for interfacing purposes are discussed in references [1,3] and need not be given here. It may be noted here that the proposed character layouts are also suitable for CRT displays because they require very simple X- and Y-deflection waveforms. Fig. 3 shows the X- and Ydeflection waveforms which have been designed for the first layout shown in Fig. l(a). The parallel output of the ROM code converter (of dimensions as discussed before) is given to a parallel-to-serial converter the output of which is applied to the grid control amplifier of the CRT. A clock and timing control unit synchronizes the grid control signal with the X- and Ydeflection waveforms which are to be vertically shifted for column and row shifting as discussed in detail in reference [4].

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Beg & Ahmed: Two Simple Bar Matrix Display Formats for Alphanumeric English Characters

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Resultant alphanumeric characters and symbols and their corresponding ASCII codes. For the character format of Fig. 1 (a). For the character format of Fig. 1 (b).

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CONCLUSION Two new bar matrix formats using 10 elements and 12 elements respectively have been presented. Using lesser number of elements as compared to the display formats already in use, the proposed schemes involve simpler electronics and consume less power. Thus they are suitable for several instrumentation applications, and can display the complete set of 64 characters. The proposed layouts are simple enough to be easily incorporated for CRT displays also.

IEEE Transactions on Consumer Electronics, Vol. 34, No. 2, MAY 1988

M. Salim Beg got his B.Sc. Engg. in 1982 and M.E. in 1984. From 1984 to 1987 he was a lecturer at the of Department Electrical Engg. A.M.U., Aligarh. He is presently a Commonwealth Scholar of research at the Dept. of Electronic & Electrical Engg., University of Technology, Loughborough, U.K. His areas of academic interest are Digital Electronics, Digital Communication and Satellite Communication.

REFERENCES l.'Optoelectronics Designer's Catalogue', Hewlett Packard, 1983. 2. S. Sherr, 'Video and Digital Electronic Displays : A User's Guide' , John Wiley and Sons, New York, 1982.

3. B.S.

Sonde, 'Transducers and Display Systems', Tata McGraw Hill, New Delhi, 1981. 4. M. Salim Beg 61 Wasim Ahmed, 'A New Bar Matrix Alphanumeric CRT Display for Arabic', IEEE Trans. Consumer Electronics, Vol.CE-33, Nov. 1987, pp. 594-598.

Wasim Ahmed was born in Azamgarh (India). He took his B.Sc. Engg: , M.Sc. Engg. and Ph.D. in Electrical Engineering from AMU, Aligarh in 1971, 1974 and 1977 respectively. He is presently Reader at the Dept. of Electronic Engineering, AMU, Aligarh. His teaching and research interest are in area of Electronics, Instrumentation and Communication Engineering in which he has published widely. He has also worked in the University of Sulaimaniyah, Iraq (1978-79) and at Al-Fatah University, Tripoli, Libya (1979-81)

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