Speccy #07 31 декабря 1996

Железо

Iron - Improvised scanner: the principle of work.

    SCANNING DEVICE


 Continued. Beginning in the sixth
magazine.

 (C) NV Velichutin



    PRINCIPLE OF THE SCANNER.

 The work is based on the scanner
transfer of information into a computer
coordinates read by the point product pictures, as well as the 
lighting conditions of a given point. Level light is 
transmitted as quantum value. In this

design scanner used
four gradations of light:


      - Light background

      - A light gray background

      - A dark gray background

      - A dark background.

 The basis of the scanner is
drum which is fixed
sheet with the image. Scanning
optical head is moved
over a sheet of original from the rail with a screw. 
Synchronous rotation of the drum and the screw by a motor and a 
system shkivov.Vraschenie passed with a rubber

Pasika.
T on the shaft of the drum set
gear, which is a
engagement with another gear, with
fewer teeth. On
driven gear mounted drive
with two rows of holes. Ratio and the number of
holes on the disc is chosen so that when you turn
drum at 360 degrees it
circumference divided by the number of
equal to 320 for the top row of holes and 256 for the bottom 
row. 

 On opposite sides in strobodiska
Each row of holes are two of the photodiode and the source
light. When turning the electrical circuit formed
rectangular pulses (sync). Sync comes with each set of holes.
Sync with the incoming
top row (their number is
640 for one rotation drum)
designed for IBM compatible computers, but with lower
number (512 per revolution drum) are designed for computers 
such as ZX-SPECTUM and PROFI. 

 Sync pulses are received in
Computer ZX-SPECTRUM and PROFI
Kempston joystick port
And the IBM printer port. By
Total received sync program established
a computer with sufficient
accuracy of the coordinates of the read points. To determine 
the beginning of the report of pulses There is a hole in gear

lamp and a photodiode. When you receive
sync with the optical head reads data
light level terms and then determine the coordinates of the
point in the screen buffer in the corresponding memory cell is 
reset or set a bit. Moving relative to the drum

a helical line optical
head reads the whole picture
original. Reading the images produced by the motion
head to the left and right
right to left. When you install
image on the drum must
to the top of the picture was located in the direction of the 
optical head.


 Of course, the mechanical design of the scanner, you can change
it depends on the specific capabilities of those who took up 
the manufacture of such devices.  Motor for the scanner must

be reversible, the speed should not exceed 120 rpm.
 If the engine is placed on
one shaft with strobodiskom, then
for gear ratio 1:8
engine speed should be
within 960 min.

(Continued in the next issue

            magazine)

             *