Devices for use in neural processing

• US 5,553,197 A
• Filed: 02/18/1994
• Issued: 09/03/1996
• Est. Priority Date: 06/21/1991
• Status: Expired due to Fees

• Current Assignee: Kings College London (University of London)
• Original Assignee: Kings College London (University of London), University College London (University of London)
• Inventors: Taylor, John G., Clarkson, Trevor G.
• Primary Examiner(s): Davis, George B.
• Application Number:
  US08/167,884
• Time in Patent Office: 928 Days
• Field of Search: 395/27, 395/22
• US Class Current: 706/41
• CPC Class Codes: G06N 3/047 Probabilistic or stochastic networks
• CPC Class Codes: G06N 3/049 Temporal neural networks, e.g. delay elements, oscillating neurons or pulsed inputs
• CPC Class Codes: G06N 3/063 using electronic means

Abstract

A device for use in neural processing comprises a plurality of probabilistic RAMs (pRAMs). The output of the pRAMs are connected in common to means for accumulating their output signals and for decaying the result of the accumulation. A thresholding circuit receives the decayed result at its input and produces an output signal when the decayed result exceeds a predetermined level.

Claims

1. A neural device which comprises a plurality of neural elements each of which has a memory having a plurality of storage locations at each of which locations a number representing a probability is stored, means for addressing the storage locations, and means for causing to appear at an output of the neural element, when the storage locations are addressed, an element output signal, the probability of the element output signal having a given one of first and second values being determined by the number stored at the addressed location, the neural elements having their outputs connected in common to means for accumulating the element output signals thereof and for decaying the result of the accumulation;

and thresholding means for receiving at its input the decayed result and generating an output signal at its output when the said decayed result exceeds a predetermined level.

2. A device according to claim 1, wherein the means for decaying comprises a voltage decay circuit.

3. A device according to claim 1, wherein the output of each of the neural elements is connected to the means for decaying via a resistor.

4. A device according to claim 3, wherein the resistor connected to each neural element is variable.

5. A device according to claim 1, wherein the addressing means of at least some of the neural elements comprises a plurality of address lines.

6. A device according to claim 1, comprising means for inhibiting a device output signal during a refractory period following a previous device output signal.

7. A device according to claim 6, wherein the inhibiting means comprises a shift register, each device output signal passing to the device output via the shift register.

8. A device according to claim 7, wherein the shift register has an effective length and is provided with a mask bit input for varying the effective length of the shift register.

9. A device according to claim 6, wherein the inhibiting means comprises a clock pulse generator for generating clock pulses and a counter for counting the clock pulses, the counter serving to inhibit the device output signal for a period determined by that required to count a predetermined number of the clock pulses.

10. A device according to claim 1, wherein the thresholding means generates an output pulse whenever the said decayed result goes from a value less than the predetermined level to a value more than the predetermined level.