Patent GB-856960-A (GB)
Title: Data storage units and logical circuit devices employing a combination of such units
IPC: G11C19/30
Filed: 1959-04-07
Abstract: 856,960. Circuits employing bi-stable dielectric elements. NATIONAL CASH REGISTER CO. April 7, 1959 [April 16, 1958], No. 11687/59. Class 40 (9). [Also in Groups XIX and XL (b)] A data storage unit comprises a pair of serially connected ferroelectric elements connected in series with an electro-luminescent device, switching means for applying potentials to said elements to polarize both elements in either the same or opposite directions, a source of read-out voltage in series with the elements and the electro - luminescent device to cause the emission of radiant energy from the latter only when the elements are polarized in the same direction, and at least one photo-sensitive element optically coupled to the electro-luminescent device and responsive to such energy to change from one state to another. Basic storage unit, Fig. 1. Connection to a potential source 33 saturates ferro-electric elements 20, 21 in opposite directions, whereas connection to a potential source 34 saturates them in the same direction. In the first case when an alternating potential 26 is connected for read-out purposes, the associated electroluminescent device 28 remains inert, whereas in the latter case the device 28 is activated and illuminates a photo-cell 42 to produce an output across terminals 43, 44. Fig. 4 shows a shift register comprising a number of such units. Each of the stages OS-9S has a unit A for storage and read-out, while the stages OS-8S also have a unit B for transfer. Initially all the units are in the oppositely saturated state, i.e. they register O. If now the photo-cell 74 of unit A of stage OS is illuminated unit A is switched to store 1. The next shift pulse on common lead 55 excites electro-luminescent element 65 of this unit which therefore illumines photo-cell 74 of the related transfer unit B which therefore switches to 1 condition. The next shift pulse applied to common lead 56 switches on the A unit of the next stage 1S. At the same time electroluminescent element 76, which is optically coupled to photo-cells 72 of all the A units, operates to restore the A unit of the first stage to 0 condition. As shift takes place from an A unit to a B unit the preceding B unit is similarly restored by electro-luminescent element 75. An output may be taken from stage 9S. Inputs and outputs may be in series or parallel form. Fig. 6 shows a ring counter generally similar to Fig. 4. The last stage 9C has both A and B units. An external control means 89 causes the production of the square waves which are counted. Transfer to a higher denomination may be effected by optical means. Fig. 7 shows a shift register which can operate in forward or reverse. Each stage OSR-8SB has two storage units C, D while the last stage has a C unit only. In series with the ferro-electric elements 126, 127 of each unit are two branches, each comprising a photocell such as 128 in series with an electroluminescent element such as 130. The electroluminescent elements 130, 131 are optically coupled to the photo-cell 140 of the preceding and succeeding units, respectively, whereby dependent on the position of coupled switches 152, 153 shift takes place in a backward or forward sense, respectively.