US3740568A

US3740568A - Pushbutton lock

Info

Publication number: US3740568A
Application number: US00176528A
Authority: US
Inventors: S Ikeda
Original assignee: Niles Parts Co Ltd
Current assignee: Niles Parts Co Ltd
Priority date: 1970-10-29
Filing date: 1971-08-31
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19

Abstract

This invention relates to a pushbutton lock which unlocks only when the right combination of numbers is pushed in the proper order within a short period. Said lock is provided with two transistors, one of them actuating relays to maintain contacts for an unlocking solenoid while the other controls the time constant of the circuit. If a wrong button is pushed down after one or more right buttons, the procedure should be repeated anew.

Description

United States Patent 1 Ikeda 3,740,568 June 19, 1973 PUSHBUTTON LOCK [75] Inventor: Sadatoshilkeda, Itakomachi,

Japan I [73] Assignee; Niles Parts Co. Ltd., Tokyo City,

Japan [22] Filed: Aug. 31, 1971 [21] Appl. No.: 176,528

[30] Foreign Application Priority Data Oct. 29, 1970 Japan 45/95659 [52] US. Cl. 307/10 AT, 317/134, 307/139,

[51] Int. Cl. H02g 3/00 [581 a Field of Search 317/134; 307/10 AT,

[56] References Cited UNITED STATES PATENTS 3,320,490 5/1967 Beck et a1 317/134 3,515,340 6/1970 Mika 317/134 X 3,576,536 4/1971 Wolfe 317/134 3,633,167 1/1972 Hedin 317/134 X Primary Examinerl-1erman J. l-lohauser Att0rney-John C. Holman et a1.

[57] ABSTRACT This invention relates to a pushbutton lock which unlocks only when the right combination of numbers is pushed in the proper order within a short period. Said lock is provided with two transistors, one of them actuating relays to maintain contacts for an unlocking solenoid while the other controls the time constant of the circuit. If a wrong button is pushed down after one or more right buttons, the procedure should be repeated anew.

2 Claims, 3 Drawing Figures Patented June 19, 1973 2 Shwets-heet l Patented June 19, 1973 2 Sheets-Sheet 2 1 PUSHBUTTON LOCK This invention relates to a pushbutton lock.

This is a transistorized device having a number of numbered pushbuttons arranged on a panel with a reset switch. As this lock opens only when the right combination of numbers is pushed in the proper order within a short period, it is especially useful for automobiles to lock doors, trunk or the hood, or ignition system so as to reduce the chances of having cars stolen as well as screening drunks.

There are two kinds of pushbuttons. The first pushbuttons are momentary-contact switches bearing the key numbers and the second pushbuttons are momentary-open switches bearing numbers other than the key numbers.

The key numbers for opening the lock are a combination of more than two numbers.

This lock is provided with two transistors. Of these transistors, one determines the time constant of the circuit when the reset switch is closed while the other operates the relay when the correct pushbuttons are pushed.

In order to understand the invention, reference will now be made to the accompanying drawings, wherein FIG. 1 shows the pushbutton panel of the invented lock,

FIG. 2 shows the circuit diagram of the most simple embodiment of the invention, and

FIG. 3 shows the circuit diagram of another embodiment wherein four key pushbuttons are employed.

The lock according to this invention is provided with, for instance, numbered pushbuttons, l, 2, 3,4, 5, 6, 7, 8, 9 and 0.

In order that the principle of the invention may be readily understood, the most simple embodiment is shown in FIG. 2 wherein the combination of only two numbers, for example, 5, 4 is used, as key numbers.

As shown'in FIG. 2, the positive terminal B+ ofa battery is connected to the emitter of the transistor T2 through a reset switch SW and a series of

pushbuttons

0, 1, 2, 3, 6, 7, 8, 9. Between the positive terminal B+ and the negative terminal 3- of the battery, a switch C, which changes contact by the action of a relay coil RC,, pushbutton 4'and load L are connected in series. One contact A,- of the switch C, is connected to the negative terminal 8- through a capacitor C as well as to the base of the other transistor T, through a variable resistor VR. The collector of said transistor is connected to the emitter of the transistor T through a resistor R, as well as to the base of the transistor T while the emitter of the transistor T, is connected to the negative terminal B"" through a resistor R,. The collector of the transistor T is connected to a switch C, which changes contact by the action of the relay .coil RC,. Initially, contact A, of the switch C, is connected to one contact of the pushbutton 5 while the other contact of said pushbutton is connected to the relay coil RC,. The other contact B, of the switch C, is connected to the relay coil RC,. Diode DA is shown across the relay coil RC, in order to protect the transistor against high transient voltage generated when the relay coil is turned off. Instead of diode, capacitor can also be used for protection.

The capacitor C and resistor VR form the RC network in the base circuit of the transistor T,. By adjusting the time constant of said RC network by means of variable resistor VR, the time delay can be set to meet the needs of the individual owner.

The function of this lock is as follows:

First, close the reset switch SW. Current will be supplied to the capacitor C and base of the transistor T, through the resistor VR whereby the capacitor C will be charged and the transistor T, will become conductive.

Next, push the button 5. Then, current will be sup plied to the relay coil RC, through now conductive transistor T and contact A, of the switch C,. By the action of the relay coil RC,, contact of the switch C, changes from A, to B, and contact of the switch C, changes from A, to 8,. Through contact B,, selfholding current will be supplied from the positive terminal 8+ to the relay RC,.

Change of contact from A, to B, causes the discharge of the capacitor C whereby the transistor T, which is biased off by the charged capacitor will shut down the circuit when said capacitor has discharged. At the same time, the other transistor T becomes unconductive.

Finally, push the button 4. Then, current will be supplied to the load L from the positive terminal B+ through contact B, and pushbutton 4 whereby unlocking will be effected.

During the procedure, if one of the pushbuttons 0, l, 2, 3, 6, 7, 8 or 9 be punched by mistake, current supply from the battery to the relay RC, will be suspended whereby since the relay will not be able to maintain the self-holding, contacts of the switches C, and C, will return to the initial state.

As is clear from the above, in order to open the lock, the pushbuttons should be pushed not only in the proper order but also within a short time defind by RC network.

FIG. 3 shows a more complicated embodiment of this invention. l-Iere, combination of four numbers, for example, 5284 is chosen.

The function of this device is similar to that of the embodiment shown in FIG. 2.

By punching the

pushbuttons

5, 2 and 8 in the proper order, switches C, C C, will close under the actions of the energized relays RC, RC RC,, respectively. Therefore, when the last pushbutton 4 be pushed, current will be supplied to the load L to open the lock.

Switches C, C, change contact by the action of the relays RC RC,, respectively.

Diode DB are provided for regulating the polarity of current to ensure correct operations of the circuits.

Here, too, the pushbuttons should be pushed in the proper order within a short time.

Having now described my invention, what I claim is:

1. A pushbutton lock circuit comprising, in combination: a series circuit including a battery, a plurality of momentary-open type pushbutton switches, and a first transistor; a plurality of momentary-contact type pushbutton switches including at least a first and last momentary-contact type pushbutton switch; a resistancecapacitance discharge network connected to the base of said first transistor; a load device; first and second multi-position controllable switch means; and a relay means for controlling said first and second multiposition switch means; said first multi-position switch means being coupled to said battery and selectively supplying current to said RC network in a first position thereof to turn on said first transistor, and supplying current to said load device through said last momentary-contact type pushbutton switch in a second position thereof, said RC network discharging in said second position so as to cut off said first transistor; a second transistor having its emitter connected to said battery through said plurality of momentary-open type pushbutton switches, the collector of said second transistor being coupled to supply current to said second switch means, the base of said second transistor being connected to the collector of said first transistor such that both transistors conduct and are cut off at the same time; said second switch means supplying current through said first momentary-contact type pushbutton switch to initially energize said relay means in a first position thereof, and supplying self-holding current to said relay means in a second position thereof, said relay means, when energized, switching said first and second multi-position switches from said first positions to said second positions thereof; whereby said load will be energized only when said momentary-contact type pushsecond switch means and its respective relay.

Claims

1. A pushbutton lock circuit comprising, in combination: a series circuit including a battery, a plurality of momentary-open type pushbutton switches, and a first transistor; a plurality of momentary-contact type pushbutton switches including at least a first and last momentary-contact type pushbutton switch; a resistance-capacitance discharge network connected to the base of said first transistor; a load device; first and second multiposition controllable switch means; and a relay means for controlling said first and second multi-position switch means; said first multi-position switch means being Coupled to said battery and selectively supplying current to said RC network in a first position thereof to turn on said first transistor, and supplying current to said load device through said last momentary-contact type pushbutton switch in a second position thereof, said RC network discharging in said second position so as to cut off said first transistor; a second transistor having its emitter connected to said battery through said plurality of momentary-open type pushbutton switches, the collector of said second transistor being coupled to supply current to said second switch means, the base of said second transistor being connected to the collector of said first transistor such that both transistors conduct and are cut off at the same time; said second switch means supplying current through said first momentarycontact type pushbutton switch to initially energize said relay means in a first position thereof, and supplying self-holding current to said relay means in a second position thereof, said relay means, when energized, switching said first and second multi-position switches from said first positions to said second positions thereof; whereby said load will be energized only when said momentary-contact type pushbutton switches are pushed in proper sequence from first to last within a predetermined period of time corresponding to the discharge time of said RC network.

2. A pushbutton lock circuit as defined in claim 1, wherein each of the other momentary-contact type pushbutton switches include additional relay means and second multi-position switch means coupled in parallel branch circuit with said first-mentioned relay means, and additional first multi-position switch means coupled in series circuit with said load, each of said other momentary-contact type pushbutton switches being connected in series circuit between its respective second switch means and its respective relay.