GB2222524A

GB2222524A - Flicker-fusion apparatus

Info

Publication number: GB2222524A
Application number: GB8821277A
Authority: GB
Inventors: Kasuo Saito; Kinnosuke Jimbo
Original assignee: JIMBO ENGINEERING CORP
Current assignee: JIMBO ENGINEERING CORP
Priority date: 1988-09-12
Filing date: 1988-09-12
Publication date: 1990-03-14
Also published as: GB8821277D0; DE3831947A1

Description

2222524 FLICKER-FUSION APPARATUS This Invention relates to flicker-fusion

alertness testing apparatus.

Flicker-fusion alertness testing apparatus generally comprises a luminous indicator driven by a variable-frequency oscillator which As manually adjustable by the person whose alertness is being tested, The subject being tested observes the luminous indicator as he or she turns the frequency control knob from the upper limit of the range of the flicker frequency downwardly until the light, which appears continuous at the upper end of the range, begins to flicker as far as the testee is concerned, The frequency at which the flickering of the luminous element can first be discovered indicates the level of alertness of the testee. Such equipment can be used In detecting fatigue in factory workers, inebriation in car drivers and anoxia in h1gh-altitude pilots, among other uses. A search of the records of the United States Patent andTrademark office revealed the following patents which are related to, but do not anticipate the present invention:

U.S. Patent No. 2,495,708 (Draeger, et al) U.S. Patent No. 2,675,512 (Krasno) U.S. Patent No. 3,761,921 (Adler, et al) U.S. Patent No. 4,324,460 (Daley).

A common characteristic of all of the apparatus disclosed In the prior art is that the testee turns a frequency-varying knob, as a result of which the rate of change of frequency is not constant and the critical frequency at which he can first discern flicker is not determined accurately. Also, such prior art devices are bulky and not easily applicable to field use,

Therefore, it is an object of the present invention to overcome the general disadvantages of prior art devices, as set forth hereinbefore.

It is a further object of the present invention to provide a flickerfusion alertness meter which accurately determines the critical flickerfusion frequency.

It is a still further object of the present Invention to provide a flicker-fusion fatigue meter which is lightweight, portable and accurate.

By automatically reducing the flicker frequency by a fixed decrement at fixed time intervals with the testee being required to only push a button once to start the :a test and once more to stop it when he first detect& flicker, and automatically indicating the frequency at each step, the accuracy of detection of the critical flicker frequency, and, consequently, the accuracy of the analysis of the condition of the testee, can be greatly enhanced.

The present Invention can beet be understood by referring to the description which following taken in conjunction with the drawings herein, In which:

Fig. 1 is a front-elevational view of the flickerfusion testing apparatus according to the present invention; Fig. 2 is a side-elevational view of the apparatus of Fig. 1; and, Fig. 3 is an electrical block diagram of the flickerfusion apparatus of Fig. 1.

In Figs. 1 and 2, flicker-tusion testing apparatus or meter-8 includes case 30 having two halves 30a and 30b. Case 30, with its clam-shell halves 30a and 30b, encloses 41 the electronics and the power supply associated-with the flicker-fusion apparatus of this invention. Half 30a of case 30 carries In its outer surface luminous element 10, which may be an LED 10. That Is what the testee observes. There Is also provided In case half 30a a frequency indicator 12, which indicates the frequency of operation of the apparatus at any in6tant during Its use, start-stop button 13, which is utilized by the testee to start the test and to end it when he is able to discern the flicker, and meter or apparatus on-off switch 14. The size of the apparatus or meter 8 is kept sufficiently small so that the apparatus can be carried in the pocket of a coat. The meter is operated off of a small number of AA primary cells which are carried within case 30 making the meter operable at points removed from external power sources, Thus the meter of Figs, 1 and 2 may be taken to any point in a production line without the inconvenience of finding a source of mains power for operation of the device.

In Fig. 3, operating power for the integrated circuits utilized in meter 8 is provided from battery 17 thru on-off switch 14, With switch 14 closed, push-button switch 13 in control module 16 puts a momentary ground on the clock input terminal of an MC14013 microchip configured as a bistab2e flip-flop and causes that flipflop to change states. This is the latch circuit 18 in 4 Fig. 3. The MC14013 microchip is a standard chip available from Motorola and the details of such a latch circuit are well known to those skilled in the art and need not be discussed here. When the Q terminal of.the Integrated circuit type MC24013 is "high" that "high" appears on bus 32 providing a start signal to pre-setting matrix 19 which "zeroes" counter 20. That "high" also appears on bus 34 putting a "high" signal on pin 5 of NAND gate 23 which is of the integrated circuit type 4011 available from Motorola. Timing-standard oscillator 22 generates two signals one at 10,24 Hz, which is applied to pin 6 of NAND gate 23, and another signal at 1024 Hz which is applied to phase-locked loop 24, With pin 5 of NAND gate 23 "high" and a 10.24 Hz signal from timing- standard oscillator 22 applied to pin 6 of NAND gate 23, the 10.24 Hz signal passes thru NAND gate 23, appearing at the output pin 4, thereof, and consequently being provided to counter 20.

Counter 20 comprises three IC's of the type MC14510 each of which represents a decade In the desired output count. The integrated circuits In counter 20 are presettable up-down counters and pre-setting matrix 19 Is merely the necessary wire Interconnections to pre-Set the maximum count of counter 20 at 500 Hz, for example. The binary signals from counter 20 are provided thru multi- 9 conductor bus 34 to indicator driving circuit 21 which may be a three- decade indicator-driving circult comprising three integrated circuit type MC14511 chips driving three 7-segment indicators for three decades of displayed counting information. The 7-segment indicators may be of the type GL-8N03D. Thus indicator 12 and indicating means 11 are controlled by counter 20 and produce a three-digit output Indication e.g. 49.9 Ez, which corresponds to the bAt rate or frequency of pulses applied to IED 10.

The output bits from counter 20, in addition to being provided to indicator driving circuit 21 by way of bus 34 are provided to divider circuit 25 through bus 36. Those output bits begin at the rate of 500 Hz and are reduced In rate 1 V2 every.09766 seconds. For ease of comprehension it may considered that the output count from counter 20 Is reduced by 1 Hz every 1/10 second. This Is a result of Interaction between the 10.24 Hz signal provided by standard occillator 22, through NAND GATE 2.1, anti the counting circuits of counter 20. Divider circuit 25 includes a TC40102 integrated circuit which is available from Texas Instrument Co. or an RCA CD4012B. This Is an 8stage pre-settable, synchronous BCD Down Counter. Bus 36 also feeds the output signal from counter 20 Into an MC14510 down counter which is coupled at its clock output terminal to the clock Input terminal of the TC40102 t 1 in divider 25. Divider circuit 25 also receives an Input signal from the voltage-controlled oscillator in phaselocked loop 24. That oscillator initially Is functioning at 512 KHz at the same time as the output signal from counter 20 is at 500 Hz. The Input signal at terminal 36 of divider circuit 25 is divided by the signal arriving at divider circuit 25 from counter 20. Thus, initially, the 512 KHz signal entering divider circuit at terminal 38 results in a signal at 1024 Hz at output terminal 40 of divider circuit 25. That output signal at 1024 Hz from divider circuit 25 is provided to input terminal 42 of phase-locked loop 24. Simultaneously, there Is provided to input terminal 44 of phase-looked loop 24 by way of bus 46 a reference signal at 1024 Hz. This signal is used In conventional fashion within phase-locked loop 24 to control the phase of the 1024 Hz signal derived from divider circuit 25 and, since that signal from divider circuit 25 Is Initially generated by the voltage-controlled oscillator within phase-locked loop 24, the phase of oscillation of that oscillator Is controlled to assure stability of the signal ultimately applied to LED 10.

When the output from counter 20 is caused by the input 10.24 Hz signal to move from an output bit rate of 500 Hz to the next downward step of 499 Hz the voltage control oscillator in phase-locked loop 24 is stepped down In its operating frequency from 612 KHz to 510.976 KHz. Divider circuit 25 divides that signal by 499 Hz to again produce an output signal at terminal 40 of divider circuit 25 at the rate of 1024 Hz so that the phase locking ability of phase-locked loop 24 continues since the comparison continues between two signals at 1024 Hz. This procedure continues with the counter 20 putting out every approximately 1/10 second a signal at a rate reduced by 1 Hz from the previous signal. This procedure continues until the person being tested pushes push-button switch 13 Indicating that he can now distinguish individual light Impulses from TiED 10. At that time NAND gate 23 is disabled and outputs a zero signal as a result of which counter 20 no longer continues its downward counting. Indicator 12 then Indicates, to 1/10 Hz the flicker- frequency at which fusion disappears in the eye of the testee.

Meanwhile the stabilized output signal from the oscillator in phaselocked loop 24 Is applied to divider cArcult 26 which dAvides by the factor 10240 and outputs a signal to LED driver 27 for ultimate application to LED 10. Simple calculations will show that as the output signal from the voltagecontrolled oscillator in phase locked loop 24 proceeds from 512 KHz downwardly in steps, by reason of the division In divider circuit 26 the signal 1? applied to LED 10 will change from 50 Hz to 49.9 Hz and downwardly, 0.1 Hz at a time. Thus, in one second, the flashing rate of LED 10 will be reduced by I Hz.

The purpose of using the high-frequency signal, namely one at 512 KHz and dividing it by the large factor 10240 is to achieve a high degree of accuracy in the readout on indicator 12. Thus, the condition of the person being tested can be determined more accurately. The phase-locked loop circuit described herein assures that the fusion-frequency is accurately determined and is reproducible.

While reference has been made to specific 1xitegrated circuit types, equivalent types from other manufacturers may be utilized. The individual circuit such as the counters and dividers can be found in most Instruction manuals on Integrated circuits. Thus the detailed description of the interconnection of the circuits is not required. Further, while operation of the claimed apparatus has been fully described in terms of the frequency of flicker being reduced from, for example, 50 Hz to a frequency at which fusion of the light Impulses ceases and individual flashes are detected by the testae, it should be understood that the equipment may be operated in the opposite mode, that is, the frequency may be increased from one at which the testee can detect the

R individual impulses of light until those Individual imPulses fuse, at which time the test Is completed.

-1

Claims

CLAIMS.

1. FlIcker-fusion apparatus, Including: a luminous element to be viewed by the person whose condition As being tested; variable-frequency driving means coupled to said luminous element for causing the flickering of such element; control means coupled to said variable-frequency driving means for automatically and periodically changing the frequency of operation thereof in discrete, predetermined steps in a predetermined direction; display means coupled to said variable frequency driving means for displaying, at any Instant, the frequency of flicker of said luminous element; means coupled to said variable-frequency driving means and Including a push-button mechanically operable by the person being tested selectively to produce "on" and "ofC conditions in said "on"-"off" means; said "on"-"off" means, when switched to the "off" condition being effective to suspend the automatic changing of the 14 frequency of operation of said vzkriable- frequency driving means without extinguishing the last frequency Indicated on said Indicator; and, means for providing operating power for said flicker-fusion apparatus.

2. Apparatus according to Claim 1 in which said variable-frequency driving means includes a down-counter.

3. Apparatus according to Claim 1 in which said luminous element is an LED.

4. Apparatus according to Claim 1 In which said variable-frequency driving means includes a phase-locked loop.

5. Apparatus according to Clalm 1 In.which said varlable-frequency driving means includes a standard.oscillator.

6. Apparatus according to Claim 6 In which said standard-timing oscillator provides two output signals, one at 10.24 Hz and the other at 1024 HZ.

14L 1 1

7. Apparatus according to Claim 1 in which sald "on"-"off" means Includes a latch cIrcult.

8. Apparatus according to Claim 1 In which said "on"-"off" ineans includes a momentarycontact push-button and a latch circuit coupled to and controlled by said momentary-contact pushbutton.

9. Apparatus according to Claim I In which said control means changes the frequency of operation of said variable-frequency driving means by one Herz each one-tenth of a second until stopped by operation of said "on'.'"off" means.

10. Apparatus according to Claim 1 In which the upper frequency of operatAon of said variablefrequency driving means As 500 NZ.

11. Apparatus according to Claim 1 in which said control means reduces the frequency of operation of said variable-frequency driving means by one-Herz per one-tenth of a second and the Initial frequency of operation is 500 Hz.

11 - fi-

12. Apparatus according to Cl-aim 1 which includes, in addition, a frequency divider circuit ween said vari able---fre que ncy driving means coupled bet L and said luminous element..

13. Fusion-flicker apparatus substantially as hereinbefore described with reference to the accompanying drawings.

z Published 1990 atThe Patent OMCS. State House. 86. ? t High Holbium. L4ndon WC1R 4TP Further copies maybe obwnedfmm The Patent Omce. S3ass Branch. St Mary Cray. Orpuieton. K:n,. MR5 3RD. PrInted by MuMplex techniques Itd. St Mary Cray. Menu Con. 1.87