US3808454A

US3808454A - Illuminator energizing device

Info

Publication number: US3808454A
Authority: US
Inventors: T Toda; Y Kuroda
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1971-11-13
Filing date: 1972-10-31
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30

Abstract

An illuminator energizing device, especially for use with a microfilm reader or the like, comprises input means, time limit means, switch means, pulse generating means and illuminator energizing control means. The time limit means is responsive to the signal from the input means. The switch means is responsive to the output signal from the time limit means and includes a first switching circuit assuming ON position when the output voltage of the time limit means exceeds a predetermined level and assuming OFF position when said output voltage is below the predetermined level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of the first switching circuit, respectively.

Description

United States Patent 11 1 Toda et al. Apr. 30, 1974 ILLUMINATOR ENERGIZING DEVICE 3,382,417 5/1968 Armstrong 307/293 x 1 3,666,988 5/1972 Bellis 315/362 [75] Invent: a fi gg 2? Yasu Kumda, 2,823,582 2/1958 Gray 353/27 awas 1, o apan [7 3] Assignee: Canon Kab Kaisha, y Primary Examiner-Robert K. Schaefer Japan Assistant Examiner-M. Ginsburg [22] Filed: Oct 31 1972 Attorney, Agent, or Firm-Flynn & Frishauf [21] Appl. No.: 302,429

[ ABSTRACT [30] Foreign Application p i it Data An illuminator energizing device, especially for use Nov 13 I971 Ja an 46406455 with a microfilm reader or the like, comprises input 1971 Japan 46408059 means, time limitmeans, switch means, pulse generatp ing means and illuminator energizing control means. [52] U 8 Cl 307/141 307/293 The time limit means is responsive to the signal from [51] 140" 7/00 the input means. The switch means is responsive to [58] Field 4 141 8 the output signal from the time limit means and in- "I" 1 cludes a first switching circuit assuming ON position 360 5 317/142 141 R when the output voltage of the time limit means exceeds a predetermined level and assuming OFF position when said output voltage is below the predetermined level, and a second switching circuit assuming [56] References Cited OFF and ON positions in response to the ON and OFF UNITED STATES PATENTS positions of the first switching circuit, respectively. 3,376,429 4/1968 Atkins et'al. 307/l4l 2,339,750 l/l944 Bartholyi 317/142 R 15 Claims, 8 Drawing Figures PRIOR ART Trl Pmamewaaom 3808.454

SHEET 2 UF 3 FIG. 4

UJT

FIG. 5

PATENIEUAPR so 1974 MSW |O I .1. I f ILLUMINATOR NERGIZING DEVICE BACKGROUND OF THE INVENTION l. Field of the'lnvention v This inventionrelates to an illuminator energizing device, and more particularly to an illuminator energizing device for efficiently energizing an illuminator employed in a microfilm reader or the like.

2. Description of the Prior Art I The illuminator energizing device heretofore used especially with a microfilm 'reader' or the like has been arranged as shown in FIG. 1 of the accompanying drawings, namely, such that closing of a power switch SW causes a lamp L to be turned on by a commercial frequency voltage AC. Therefore, the lamp L remains film in the machine may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device for enabling efficient use of an illuminant or light source.

It is another object of the present invention to provide a device which is sufiiciently responsive to various input means for facilitating the energization of an illuminator. i

It is still another object of the present invention to provide a device which enables elimination of any damage imparted to afilm or the like being illuminated.

According to an embodiment of the present invention, the device comprises input means, time limit means, switch means, pulse generating means and illuminator energizing control means. The time limit means is operable in response to the operation of the input means, and the switch means, responsive to the time limit means, includes a first switching circui assuming ON positionwhen the output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON-positions in response to the ON and OFF positions of the first switching circuit, respectively.

The pulse generating means is inoperativein the ON position of the second switching circuit but is switched on and off with the charging and discharging of a pulse.

generating capacitor in the'OFF position of the second switching circuit. The pulse generation renders conductive a gated switching element of the illuminator control means inserted in the lamp circuit to which is applied a commercial frequency voltage.

When a user begins to operate a reader orthe like, an operating signal is applied from the input means to the time limit means to operate the switch means in accordance with such signal. In response thereto, the pulse generating means generates a pulse-to effect the illuminator energization. Thereafter, upon completion of the operation, i.e., after a predetermined time set by the time limit circuit, the energizing signal is cut off.

The invention will become fully apparent from the following detailed description thereof taken in conjunction with the accompanying drawings, in which:

, tions'in case of application of DC input signals;

FIG. 4 is a circuit diagram showing the electrical connection employing input means and DC input signals according to another embodiment of the present invention; I i FIG. 5' is a perspective view of a microfilm reader 'with the device of the present invention mounted thereon; r I ,FIG. 6 is a transverse cross-sectional view of the input switch portion of the reader shown in FIG. 5;

FIG. 7 shows the electrical connection in an embodiment of the high impedanceamplifier circuit used as input means; and

FIG.,8 illustrates waveforms explaining the operations in case of application of AC input signals when the high impedance amplifier circuit is used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 2, there is shown an arrangement according to an embodiment of the present invention which comprises a'time constant circuit 2 including a transistor Tr] to which is applied a control signal as input voltage, a'first switching circuit 3 consisting of a transistor Tr2 turned on when the output voltage of the time constant circuit exceeds the Zener voltage V of a Zener diode ZD and turned off when the output voltage of the time constant circuit is below the Zener voltage V a second switching circuit 4 consisting of a transistor Tr3 turned off and on in response to the ON and OFF positions of the first switchingcircuit 3, and a'pulse generator circuit 5 consisting of a unijunction transistor UJT inoperable in the ON position of the second switching circuit 4' buttumed on and ofi in response to the charging and discharging of a pulse gencrating capacitor C2 during the OFF condition of the second switching circuit 4 to thereby close a Triac in a lamp circuit 6 to which is applied a commercial frequency voltage AC. T

In the above-described arrangement, a DC input voltage as shown in FIG. 3a is applied through a diode to the capacitor C1 "in the time constant circuit 2 to chargethe capacitor.

The charging voltage V of the capacitor C1 renders the transistor Trl conductive, and when its emitter I voltage or the output voltage V0 of the time constant in turn renders the transistor Tr3 in the second switching circuit 4 non-conductive. As a result, the capacitor C2 of the pulse generator circuit 5 is charged to render the transistor UJT conductive, whereafter the charge in the capacitor C2 is discharged through the. primarywinding of a pulse transformer T to thereby render the' transistor UJT non-conductive. In this way, the transistor UJT is turned on and off with the charging and discharging of the capacitor C2 to generate a pulse in the secondary winding of the pulse transformer T,'so that the Triac is closed to turn on the lamp L with a commercial frequency voltage AC. In'FIG. 3c, the period of time T is the duration of the DC input voltage, which of course is the period during which the lamp L is turned on.

When the user has completed his operation, i.e.,

when the period of time T has terminated, the DC input voltage is cutoff as indicated in FIG. 3a to cause the capacitor C1 to discharge through the base emitter of the transistor Trl until the output voltage V of the time constant circuit 2 is gradually reduced to a level below the Zener voltage V as shown in FIG. 3b, whereupon the transistor Tr2 is rendered nonconductive and thereby the transistor Tr3 is rendered conductive. As a result, the capacitor C2 is shortcircuited by the conduction of the transistor Tr3 and thus it is not charged, whereby the transistor UJT is maintained in its OFF condition. Thus, the secondary winding of the pulse transformer T generates no pulse, so the Triac is opened to turn off the lamp L.-The period of time T in FIG. 3c is the period from the opening of the normally open contact of microswitch to the turn-off of the lamp L. Once this period has passed, the transistor T r3 maintains its ON position to keepthe lamp L turned off unless the reader is operated to close the microswitch (not shown).

FIG. 4 shows another embodiment of the present invention which employs a' self-return switch as input means. In this embodiment, the microswitch Msw for I applying a DC voltage to the transistor Trl is provided,

as shown in FIG. 5, on the center portion of a carrier arm 8 which may be touched by the users hand during the operation of the reader 7. FIG. 6 shows a transverse cross-sectional view of the switch portion so provided. With this arrangement, operation of the reader 7 causes the-users hand to touch a microswitch plate 10 supported by the support arm 8, thus closing the normally open contact N of the microswitch Msw as shown in FIG. 3a to permit a'DC voltage to be supplied to the capacitor C1 in the time'constant circuit 2 to charge the capacitor. Also in FIG. 4, in the same manner as described previously, the charging voltage V of the capacitor C l renders the transistor Trl conductive,

- and when its emitter voltage or the output voltage V of the time constant circuit 2 exceeds the Zener voltage V of the Zener diode ZD as shown in FIG. 3b, the transistor Tr2 in the first switching circuit 3 is rendered conductive and this in turn renders the transistor Tr3 in the second switching circuit 4 non-conductive. As a result, the capacitor C2 of the pulse generator circuit 5 is charged to render the transistor UJT conductive, whereafter the charge in the capacitor C2 is discharged through the primary winding of the pulse transformer T to thereby render the transistor UJT non-conductive. In this way, the transistor UJT is turned on and ofi with the charging and discharging of the capacitor C2 to generate a pulse in the secondary winding of the pulse transformer T, so that the Triac is closed to turn on the lamp L with a commercial frequency voltage AC. In FIG. 30, the period of time T is the period during which the-normally open contact N of the microswitch Msw is closed, and this of course is the period during which the lamp L is turned on.

When the users hand is released from the microswitch plate 10 upon completion of the operation of the reader 7, the normally open contact N of the microswitch Msw is opened as shown in FIG. 3a, to cause the capacitor C1 to discharge through the base-emitter of the transistor Trl until the output voltage V of the time constant circuit 2 is gradually reduced to a level below the .Zener voltage V as shown in FIG. 3b, whereupon the I transistor Tr2 is rendered nonconductive and thereby the transistor Tr3 is rendered conductive. As a result, the capacitor C2 is shortcircuited bythe conduction of the transistor Tr3 and thus it is not charged, whereby the transistor UJT is maintained in its OFF condition. Thus, the secondary winding of the pulse transformer T generatesno pulse, so the Triac is opened to turn off the lamp L. The period of time T in FIG. 30 is the period from the opening of the normally open contact N of microswitch Msw to the tum-off of the lamp L. Once this period has passed, the transistor Tr3 maintains its ON position to keep the lamp L turned off unless the reader 7 is operated to close the microswitch Msw.

FIG. 7 shows a high impedance input circuit employed as a precircuit. The input terminal of this circuit is of high impendance and the input signal applied thereto may be an AC voltage induced in the human body. More specifically, the present embodiment utilizes as the input means the high impedance and high gain input circuit of FIG. 7, whose output is connected as an input to the circuit of FIG. 2. Thus, when the input terminal In is touched by the users hand, the commercial frequency voltage ac induced in the human body as shown in FIG. 8a is appliedto the input terminal In and then amplified by an amplifier circuit la, ,whereafter it is rectified by a diode D and applied to the capacitorCl in the time constant circuit 2.to charge the capacitor as explained in connection with FIG. 4.

. first switching circuit 3'is rendered conductive and this in turn renders the transistor Tr3 in the second switching circuit 4 non-conductive. As a result, the capacitor C2 of the pulse generator circuit 5 is charged to render the transistor UJT conductive, whereafter the charge in the capacitor C2 is discharged through the primary winding of the pulse transformer T to thereby render the transistor UJT nonconductive. In this way, the transistor UJT is turned on and off with the charging and discharging of the capacitor C2 to generate a pulse in the secondary winding of the pulse transformer T, so that the Triac is closed to turn on the lamp L with a commercial frequency voltage ac. In FIG. 80, the period of time T is the period during which the users hand is in contact with the input terminal In, and this period during which the lamp L is T generates no pulse, so the Triac is opened to turn ofithe lamp L. The period of time T in FIG. 8c is the period from the release of the users hand from the input terminal in to the turn ofi of the lamp L. Once this period has passed, the transistor Tr3 maintains its ON position to keep the lamp L turned off unless the input terminal in is touched by the users hand.

Where the lamp Llused in thedescribed embodiments is an incandescent lamp which presents a very low resistance value at room temperatures, a surge current absorbing resistor must be inserted in the lamp circuit 6 to protect the lamp against any surge current which may flow at the moment the Triac isclosed.

According to the present invention, as will be appreciated from the foregoing, the lamp is turned on only during the period in which the input signal is being ap-. plied, i.e., the period during which the reader is being operated, plus a predetermined time after the input signal has been cut off or after the operation of the reader has been completed. This is useful to remarkably increase the service life of the lamp and to prevent the film on the reader from being thermally damaged. Furthermore, as seen in' the described various embodiments, control may be accomplished by the use of various input signals and this is highly efiective especially in applications of the present invention.

We claim:

1. An illuminator energizing control device for film readers and the like, comprising:

input means for producing an electric operating signal;

time limit means responsive to the signal from said input means for defining a predetermined time duration;

switch means responsive to the output signal from said time limit means; and

control means responsive to the output signal from said switch means for energizing an illuminator, said control means comprising means for generating a sequence of pulses during said predetermined time duration andsemiconductor means responsive to said pulses for connecting said illuminator to a source of energizing current.

2. An illuminator energizing control device for film readers and the like, comprising:

input means for accepting or producing an electric operating signal;

switch means responsive to the output signal from said time limit means;

illuminator energizing control meansv including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current supply; and I a low vvoltage direct current supply for said input means, time limit means, switch means and control means. I

3. An illuminator energizing control device accord ing to claim 2, wherein said switch means comprises a first switching circuit assuming ON position when an output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of said first switching circuit, respectively.

4. An illuminator energizing control device according to claim 2, wherein said semiconductor means is a gated switchingelement inserted in an illuminator ene'rgizing circuit to which is applied a commercial frequency alternating voltage.

5. An illuminator energizing control device according to claim 3, wherein said means for generating a sequence of pulses includes a pulse generating capacitor which is inoperative in the ON position of said second switching circuit of said switch means but operative in the OFF position of said second switching circuit.

. 6. An illuminator energizing control device for film readers and the like, comprising:

input means having a self-return switch for producing an electric operating signal;

switch means responsive to the output signal from said time limit means;

illuminator energizing control means including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current pp y; d

a low voltage direct current supply for said input means, time limit means, switch means and control means.

7. An illuminator energizing control device according to claim 6, wherein said self-return switch is provided at a location where it may be touched by a hand during operation of a reader and is connected so as to charge a capacitor through a diode in said time limit means during a brief operation of said switch.

8. An illuminator energizing control device according to claim 6, wherein said switch means comprises a first switching circuit assuming ON position when an output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of said first switching circuit, respectively.

9. An illuminator energizing control device according to claim 6, wherein said semiconductor means is a gated switching element inserted in an illuminator energizing circuit to which is applied a commercial frequency alternating voltage.

10. An illuminator energizing control device according to claim 8, wherein said means for generating a sequence of pulses includes a pulse generating capacitor which is'inoperative in the ON position of said second switching circuit of said switch means but operative in the OFF position of said second switchingcircuit.

11. An illuminator energizing control device for film readers and the like, said device comprising:

input means having high impedance amplifier means for producing a signal upon detectionof a A. C. voltage induced in a nearby human body;

switch means responsive to the output signal from said time limit means;

illuminator energizing control means including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current supply; and

12. An illuminator energizing control device according to claim I], wherein said switch means comprises a first switching circuit assuming ON position when an output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of said first switching circuit, respectively.

13. An illuminator energizing control device according to claim 11, wherein said semiconductor means is a gated switching element inserted in an illuminator energizing circuit to which is applied a commercial frequency alternating voltage.

14. An illuminator energizing control device according to claim 11, wherein said input means has its input terminal provided at a location where it may be touched by a hand during operation of a reader.

15. An illuminator energizing control device according to claim 12, wherein said means for generating a sequence of pulses includes a pulse generating capacitor which is inoperative in the ON position'of said second switching circuit of said switch means but operative in the OFF position of said second switching circuit.

Claims

1. An illuminator energizing control device for film readers and the like, comprising: input means for producing an electric operating signal; time limit means responsive to the signal from said input means for defining a predetermined time duration; switch means responsive to the output signal from said time limit means; and control means responsive to the output signal from said switch means for energizing an illuminator, said control means comprising means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting said illuminator to a source of energizing current.

2. An illuminator energizing control device for film readers and the like, comprising: input means for accepting or producing an electric operating signal; time limit means responsive to the signal from said input means for defining a predetermined time duration; switch means responsive to the output signal from said time limit means; illuminator energizing control means including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current supply; and a low voltage direct current supply for said input means, time limit means, switch means and control means.

3. An illuminator energizing control device according to claim 2, wherein said switch means comprises a first switching circuit assuming ON position when an output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of said first switching circuit, respectively.

4. An illuminator energizing control device according to claim 2, wherein said semiconductor means is a gated switching element inserted in an illuminator energizing circuit to which is applied a commercial frequency alternating voltage.

6. An illuminator energizing control device for film readers and the like, comprising: input means having a self-return switch for producing an electric operating signal; time limit means responsive to the signal from said input means for defining a predetermined time duration; switch means responsive to the output signal from said time limit means; illuminator enErgizing control means including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current supply; and a low voltage direct current supply for said input means, time limit means, switch means and control means.

10. An illuminator energizing control device according to claim 8, wherein said means for generating a sequence of pulses includes a pulse generating capacitor which is inoperative in the ON position of said second switching circuit of said switch means but operative in the OFF position of said second switching circuit.

11. An illuminator energizing control device for film readers and the like, said device comprising: input means having high impedance amplifier means for producing a signal upon detection of a A. C. voltage induced in a nearby human body; time limit means responsive to the signal from said input means for defining a predetermined time duration; switch means responsive to the output signal from said time limit means; illuminator energizing control means including means responsive to the output signal from said switch means for generating a sequence of pulses during said predetermined time duration and semiconductor means responsive to said pulses for connecting an illuminator to an alternating current supply; and a low voltage direct current supply for said input means, time limit means, switch means and control means.

12. An illuminator energizing control device according to claim 11, wherein said switch means comprises a first switching circuit assuming ON position when an output voltage of the time limit means exceeds a predetermined voltage level and assuming OFF position when said output voltage is below the predetermined voltage level, and a second switching circuit assuming OFF and ON positions in response to the ON and OFF positions of said first switching circuit, respectively.

15. An illuminator energizing control device according to claim 12, wherein said means for generating a sequence of pulses includes a pulse generating capacitor which is inoperative in the ON position of said second switching circuit of said switch means but operative in the OFF position of said second switching circuit.