2–10

SCD5580/5581/5582/5583/5584

Socket manufacturers are Aries Electronics, Inc., French-

town, NJ; Garry Manufacturing, New Brunswick, NJ; Robin-

son-Nugent, New Albany, IN; and Samtec Electronic

Hardward, New Albany, IN.

For further information refer to Appnote 22 in the current Sie-

mens Optoelectronic Data Book.

Optical Considerations

The 0.145" high character of the SCD558X gives readability

up to eight feet. Proper filter selection enhances readability

over this distance.

Using filters emphasizes the contrast ratio between a lit LED

and the character background. This will increase the dis-

crimination of different characters. The only limitation is cost.

Take into consideration the ambient lighting environment for

the best cost/benefit ratio for filters.

Incandescent (with almost no green) or fluorescent (with

almost no red) lights do not have the flat spectral response of

sunlight. Plastic band-pass filters are an inexpensive and

effective way to strengthen contrast ratios. The SCD5580/2

are red/high efficiency red displays and should be matched

with long wavelength pass filter in the 570 nm to 590 nm

range. The SCD5583/4 should be matched with a yellow-

green band-pass filter that peaks at 565 nm. For displays of

multiple colors, neutral density grey filters offer the best com-

promise.

Additional contrast enhancement is gained by shading the

displays. Plastic band-pass filters with built-in louvers offer

the next step up in contrast improvement. Plastic filters can

be improved further with anti-reflective coatings to reduce

glare. The trade-off is fuzzy characters. Mounting the filters

close to the display reduces this effect. Take care not to

overheat the plastic filter by allowing for proper air flow.

Optimal filter enhancements are gained by using circular

polarized, anti-reflective, band-pass filters. The circular polar-

izing further enhances contrast by reducing the light that

travels through the filter and reflects back off the display to

less than 1%.

Several filter manufacturers supply quality filter materials.

Some of them are: Panelgraphic Corporation, W. Caldwell,

NJ; SGL Homalite, Wilmington, DE; 3M Company, Visual

Products Division, St. Paul, MN; Polaroid Corporation, Polar-

izer Division, Cambridge, MA; Marks Polarized Corporation,

Deer Park, NY, Hoya Optics, Inc., Fremont, CA.

One last note on mounting filters: recessing displays and

bezel assemblies is an inexpensive way to provide a shading

effect in overhead lighting situations. Several Bezel manufac-

turers are: R.M.F. Products, Batavia, IL; Nobex Components,

Griffith Plastic Corp., Burlingame, CA; Photo Chemical Prod-

ucts of California, Santa Monica, CA; I.E.E.–Atlas, Van Nuys,

CA.

Microprocessor Interface

The microprocessor interface is through the serial port, SPI

port or one out of eight data bits on the eight bit parallel port

and also control lines SDCLK and LOAD.

Power Up Sequence

Upon power up display will come on at random. Thus the dis-

play should be reset at power-up. The reset will set the

Address Register to Digit 0, User RAM is set to 0 (display

blank) the Control Word is set to 0 (100% brightness with

Lamp Test off) and the internal counters are reset.

Figure 12. SCD Interface to Siemens/Intel 8031 Microprocessor (using serial port in mode 0)

U1

8031

9 RST

18

19

XTAL2

XTAL1

40

RXD

TXD

10

11

28

27

23

20 19 16

15 28

27

23

2019 16

15

1 2

1 2

6

9

6

9

13 14

13 14

DATA

DATA

SCD

SCD

SLAVE

MASTER

LOAD

LOAD

SD

CLK

SD

CLK

22

µF

TAN

.01

µF

P3.7 17

P3.3 13

P3.4 14

+