Browse Prior Art Database

Scanning Optical Reader for Merchandise and Credit Identification

IP.com Disclosure Number: IPCOM000078818D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 54K

Publishing Venue

IBM

Related People

Heidrich, PF: AUTHOR [+3]

Abstract

This description relates to an optical scanner device which is shown in side view in Fig. 1 and top view in Fig. 2.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

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Scanning Optical Reader for Merchandise and Credit Identification

This description relates to an optical scanner device which is shown in side view in Fig. 1 and top view in Fig. 2.

The device consists of two glass plates 10 and 12 the inner surfaces of which are coated with transparent electrodes 14 and 16. In between, the two plates are sandwiched with a liquid crystal 18. The two plates are not placed parallel, one plate being oblique to the other so as to form an angle tan/-1/ (D/L).

When the voltage V is applied by generator 20 between the two electrodes, the electric field intensity has different values across the plates: the intensity varies from stronger to weaker, gradually as the separation (d) between the two plates increases.

The electric field at distance x, Where the separation is d is approximately:

(Image Omitted)

If this value of electric field intensity is equal to the threshold electric field at which the liquid crystal changes its state from transparent to light scattering state, then the portion of the device, from x=o to x is opaque and the portion from x=x to L is transparent.

Now, if the applied voltage V is a sawtooth wave, as shown in Fig. 1, such that
V(t) = V(max) over T t. then the electric field intensity at position x and time t will be:

(Image Omitted)

Let e(x,t) equal the threshold electric field intensity E(th) then x over t = Nu = V(max) L over TD (x over t). Consequently, as the sawtooth wave is swept from t=o to T, the opaque portion will increase and the transparent portion will decrease from x=o to x=L, at velocity Nu.

In another embodiment, two such devices are arranged in cascade as shown in Fig. 3. Sawtooth-wave generator 22 generates a sawtooth-wave form such that the voltage increases from 0 to V(max) as time increases from 0 to T, then the top unit of the device shown in Fig. 3 works as previously described, namely the opaque portion enlarges and the boundary sweeps from...