Method 2 - 'Light-Pipe' Display Modules. Each digit consists of a stack of clear, flat plastic sheets each with one digit 0 to 9 inscribed. When a sheet is illuminated at its end by a small filament lamp the light from the lamp is piped along the sheet and is scattered by the engraved number which then can be seen quite brightly.
The 'light-pipe' display modules of a Canon Canola S , from about Different numbers being displayed by the 'light-pipe' display modules of a Canon Canola S. The photographs below are of a similar, though larger, 'light-pipe' display module to those in the Canon Canola S , which are of a more compact design but work in an identical way.
Removing the cover reveals the stack of plastic light-pipe sheets, one for each number 0 to 9 in this module. Decimal points sheets could also be fitted. Each sheet carries its number marked out in an array of conical pits in its surface.
When a light is shone into the edge of the short side of a sheet the light is piped round the corner, as with fibre optics, and illuminates the pits and so the number is seen. The bottom of the module can be removed to allow replacement of the tiny filament lamps. There is one lamp to illuminate each 'light-pipe' sheet.
This arrangement allows the numbers to be stacked closely together while being illuminated by the relatively bulky filament lamps. These 'light-pipe' numerical display modules only require the low voltage drive of the filament lamps. But the lamps have the disadvantages of high power consumption though not much of a problem in an AC-powered calculator , short operating life, and a slow response.
They were only used in a handful of AC powered desk calculators in the late s early s. First-generation VFD - A separate tube for each digit. In June the journal 'Electronics' reported that Japanese calculator manufacturers were battling the high royalties that Burroughs Corporation was asking when they produced copies of its Nixie tubes [1]. The early VFD tubes used in Sharp calculators produce very stylised digits as shown below:.
These tubes employ 8-segment digits rather than the now more familiar 7-segment digits. Here the number ' Note that the calculator electronics do not implement leading-zero suppression and so the half-height zero is used to make the display more readable. The "0", for example, has only half the height of other digits.
That way, the string of "0's" before the first significant number in the display is no longer a nuisance and there's no need to blank them out. Vacuum Fluorescent displays VFDs can be considered to be flattened cathode ray tubes. At the front of the VFD there are one or two fine wires stretching the height of the tube which form the cathode.
The cathodes are heated just to the point where they emit electrons but do not glow. The digit is formed of conductive segments which act as anodes, and each anode is coated with fluorescent material.
Applying a suitable voltage between the cathode wires and the appropriate anode segments causes electrons emitted by the cathode wires to be attracted at high speed to those anode segments. Since the segments have a fluorescent coating those which attract and are struck by the electrons glow brightly. The colour of the glow is typically green or blue, though modern displays for Hi-Fi systems produce other colours such as white, red, yellow.
Between the anode and cathode is an open grid. Applying a negative voltage to the grid switches the digit off completely. Typically, each digit is made of seven anodes arranged in the typical 7-segment pattern so that all numbers 0 to 9 can be generated.
However, some early VFD displays have 8-segment digits as below , with an extra mini-segment to give a better looking '4', which better resembles that digit in the then competing 'Nixie'-type tubes.
First-generation VFD tubes were soon produced with less stylised digits, as shown above. Note that each of the tubes here has a digit made of 8 fluorescent anodes arranged in the standard 7-segments and an extra short segment so that "4"s look better, together with a decimal point. A display using first-generation VFD tubes with 8-segment digits, as seen by the mini-segment on the right of the '4'. Though this extra segment might be present in the tubes of a calculator it was often left unused, which has little effect on the readability of the '4' and simplifies the electronics.
The Royal IC desktop calculator is unusual since it has first-generation tubes with segment digits. The Royal IC calculator display in use. Note that it still makes use of the half-height '0'. Second-generation VFD - All digits in a single tube. In the first-generation VFD each digit of the display required a separate display tube—these were used in both AC and battery powered models, with the latter often using small and narrow tubes.
The next development, the second-generation, was to reduce costs and overall size of the display by squeezing all the digits into one long horizontal tube. These tubes were widely used in early hand-held calculators. A second-generation VFD with all the digits in a single round tube. This display has 7-segment digits. Another second-generation VFD with all the digits in a single round tube. This display has 8-segment digits with the extra mini-digit for the enhanced '4', though this was not always used.
Learn more. Asked 4 years, 7 months ago. Active 4 years, 7 months ago. Viewed 1k times. Wiz Wiz 11 3 3 bronze badges. Add a comment. Active Oldest Votes. Chris Stratton Chris Stratton It is probably connected at each end via a "zebra-strip" aka "Elastomeric connector" If you want to try applying voltages to the LCD use a fine point probe to touch the connection points on it. Also, DC voltages are inappropriate. Could be just fold and compress too.
Sign up or log in Sign up using Google. Dual Calculation. Assistant Display Function. Currency Conversion Calculations. Related Links. News The intensity of the beam is modulated thus causing the screen phosphors to glow with different intensities or to even not glow at all.
The desired images to be displayed are actually retraced between 30 to 70 times each second. This keeps the images continually refreshed in the glowing screen phosphors without a flicker being perceivable to the eye. The electron beam is generated from a filament and electrically charged cathode in the back neck of the CRT. The electron beam is first passed through a control grid.
The control grid modulates the intensity of the electron beam. The higher the intensity the brighter the phosphor dot it strikes will glow.
Next the beam passes through an accelerating electrode, this will speed up the electron beam. Then the beam passes through a focusing anode. This will focus or tighten the stream of electrons. All of these elements comprise the electron gun structure housed in the neck of the CRT.
The structure on the neck of the CRT is the yoke. The yoke contains four electromagnets placed around the neck of the CRT in 90 degree increments. By varying the voltage of these four electromagnets, the electron beam can be deflected or bent to reach any location on the phosphor coated screen.
A final stage of acceleration is achieved with the high voltage anode. The familiar suction cup wire that attaches to the side of the CRT is connected to this anode. This anode is often a metalized surface on the inside of the picture tube. Many thousands of volts are applied to the anode to pull the electrons towards the phosphor coated screen. Phosphors can be formulated to emit many colors though white and green are the most popular for monochrome screens.
Additional circuitry in the calculator can create numbers, letters, and other symbols by using the control grid to turn the electron beam on and off, while simultaneously using the electromagnets to deflect the beam to the desired locations on the screen. In a Nixie Tube display each numeral is a complete, lighted cathode in the shape of the numeral. The cathodes are stacked so that different numerals appear at different depths, unlike a planar display in which all numerals are on the same plane relative to the viewer.
The anode is a transparent metal mesh wrapped around the front of the display. The tube is filled with the inert gas neon with a small amount of mercury. When an electric potential of to volts DC is applied between the anode and any cathode, the gas near the cathode breaks down and glows.
0コメント