| 摘要 |
<p>763,104. Photo-electric record sensing. INTERNATIONAL BUSINESS MACHINES CORPORATION. March 31, 1954 [April 1, 1953; April 24, 1953], No. 9424/54. Class 40 (3). In photo-electric apparatus for scanning characters on a record the character or character carrier is of the colour of maximum or minimum responsiveness of the cell or vice versa. In the embodiment of the invention shown in Fig. 2 the photo-electric detector F is of cadmium sulphide and may have an amplifier associated with it. Cadmium sulphide is highly sensitive to green light and the record K is green light of a wavelength of 5200Š. The characters on the card are of black ink although they may be red. A green filter is provided in front of the light source for filtering out blue and red. The Specification mentions the use of a zinc sulphide cell with light of 4360Š. In a modification (Fig. 3, not shown), green light is transmitted through apertures in a card to a green-sensitive photo-cell, the card being particularly greenabsorbing. Red light may be directed through to a lead sulphide cell. In the arrangement shown in Fig. 4 use is made of the fact that red light acts to repress the effect of green light. In this case red light 8 is diffusely reflected from the record card 1 and received on the cadmium sulphide photo-cell 7. When an aperture is aligned with a hole in a diaphragm 2 however green light 5 impinges on the photo-cell while the red light passes right through and is unreflected. This is said to improve the contrast of the photo-cell outputs.</p> |
