ELECTRONIC LOCKING DEVICES

Abstract: A method of unlocking a compartment such as a drawer (12) in a desk (10) where a telephone (16) is provided on the desk, the telephone being of the type where a series of frequency tones are generated for dialing a number. The user places the handset of the telephone near a microphone receiver (14) and dials a preset sequence of numbers on the telephone. The sound output from the handset is received, decoded and compared in memory with a preset code and if valid the lock is released to allow the drawer (12) to be opened.

Description: ELECTRONIC LOCKING DEVICES This invention relates to electronic locking devices. In particular the invention relates to a simple device and method for locking drawers, doors or other closable compartments in furniture such as office desks. Modern telephones which are connected to electronic switching exchanges produce a tone whose frequency depends upon the number dialed. When dialing a number in this way a series of tones are supplied along the telephone line and in addition the tones are reproduced by the ear piece of the telephone. The frequencies of the tones produced are of known internationally accepted values. We have now realized that those output tones can be used in a novel manner to control a lock for a lockable compartment in a piece of furniture on which the telephone rests, e.g. an office desk is typical. According to the invention in one aspect therefore there is provided a method of releasing a lock closing a compartment in a piece of furniture, in which the user places a telephone handset near a sound receiver and dials on the telephone a coded number, the resulting tones output produced by the telephone and received by the sound receiver being decoded and compared with a preselected code for releasing the lock, and the lock being released in the event that the said resulting tones output corresponds with the preselected code. Also according to the invention there is provided a lock release for a closable and lockable compartment in a piece of furniture, comprising a microphone capable of receiving the tones of a telephone during dialing, a decoder for receiving the output from the microphone and converting preset frequency tones to a binary data signal output, comparing means for comparing the binary data signal output with preset data corresponding to a valid sequence of tones and providing an output release signal if the comparison is valid, and means for mechanically releasing the lock when they receive the output release signal. The invention also extends to a piece of furniture such as an office desk having a lockable compartment closed by such a lock release. The invention provides a very simple way of releasing a lock and is very convenient since a separate key, which can easily be misplaced, is not necessary. Instead the invention uses the output tones of a telephone which is normally readily available. The lock is secure however since the user can preset the lock to accept a particular number code unique to him and known only to him, e.g. a series of four digits, and all he has to do is place the telephone earpiece near the microphone and dial the series of four digits on the telephone to release the lock. The microphone and decoder will be adapted to receive and decode frequencies within the well known range of frequencies corresponding to the dialing tones of electronic switching telephone exchanges. - The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagram of an office desk having a drawer which can be opened according to the invention; Figure 2 is a block diagram showing the main components of the invention; Figure 3 is a more detailed diagram of the decoder and lock release mechanism; and Figure 4 is a flow chart illustrating the operation of a lock according to the invention. As shown in Figure 1, an office desk 10 has a locked drawer 12. The lock (not shown in Figure 1) for this is normally closed but can be released as will be described. A small microphone 14 is incorporated into the body of the desk 10. Resting on the desk is a telephone 16. This is of the type which produces a series of tones when dialing a number, i.e. a different tone frequency corresponds to each number pressed on the telephone dial 18, and these frequencies are well known and internationally recognised. The telephone 16 has a handset 20. When the drawer 12 is to be unlocked, the handset is taken from the telephone and the ear piece placed close to the microphone 14 so that the dialed tones are received by it. The user then presses a known preselected code on the telephone dial, e.g. a series of four digits, and providing these are the correct digits in the correct order the drawer lock will release and the drawer 12 can then be opened. Referring now to Figure 2, the signal from the microphone 14 is first of all amplified in a simple amplifier 30 and the output fed to a tone decoder circuit 32 to analyse the output signal from the microphone. This circuit converts a particular tone frequency detected to a binary data signal output. The latter then passes to a CPU circuit 34 which checks the binary data signals against a preset memory and in the event that they agree the output passes to a mechanical lock release mechanism 36. The decoder circuit 32 is shown in more detail in Figure 3. This is conveniently in the form of an IC chip of the type known as SSi202 of SSi203 and available from Silicon Systems. In the circuit 32 the input signals from the microphone 16 pass through various band pass filters and outputs are provided on the form of either a high impedance open circuit or a low impedance, ie binary outputs. There are four outputs which can give a binary 4 bit output corresponding to a digit according to the following table: Output on pin Digit D8 D4 D2 PI 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1 0 1 0 1 0 Thus, when the tone of digit 1 is detected upon pressing the button number 1 on the telephone, the data output to the circuit 34 will be 0001 and so on. The circuit 34 includes a memory and the series of data outputs are checked against the number code stored in the memory according to the flow sheet of Figure 4. If the series of numbers is correct an output signal to actuate the lock release mechanism 36 is provided. The lock release mechanism 36 can be an electric motor or an electric solenoid driving a mechanical bolt to withdraw the bolt when actuated. The mechanical bolt can be largely conventional and include a bolt which engages a recess to hold the drawer shut, the bolt being resiliently urged to a locking position so that the drawer can be shut without withdrawing the bolt. As can also be seen from Figure 4, this bolt is withdrawn for only a preset period of time after which the bolt will again be returned to the locking position to avoid the drawer being left unlocked.

Claims: CLAIMS : 1. A method of releasing a lock for closing a compartment in a piece of furniture, in which the user places a telephone handset near a sound receiver and dials on the -telephone a coded number, the resulting tones output produced by the telephone and received by the sound receiver being decoded and compared with a preselected code for releasing the lock, and the lock is released in the event that the said resulting tones output corresponds with the preselected code. 2. A method as claimed in Claim 1 in which the sound receiver is a microphone and the tones output received by it is converted to an electrical signal. 3. A method as claimed in Claim 1 or Claim 2 in which the output from the sound receiver is decoded to provide a different binary signal corresponding to each tone produced by the telephone, and the resulting binary signals are compared with binary signals preset in memory means and if they correspond then the memory means produces an output signal to release the lock. 4. A method as claimed in any preceding claim in which the lock comprises a mechanical bolt engaging a recess and electrical driven release means to withdraw the bolt in the event that the said resulting tones output corresponds with the selected codes. 5. A method of releasing a lock closing a compartment in a piece of furniture, substantially as herein described with reference to the accompanying drawings. 6. - A lock release for a closable and lockable compartment in a piece of furniture, comprising a microphone capable of receiving the tones of a telephone during dialing, a decoder for receiving the output from the microphone and converting preset frequency tones to a binary data signal output, comprising means for comparing the card binary data signal output with preset data corresponding to a valid sequence of tones and providing an output release signal if the comparison is valid, and means for mechanically releasing the lock when the output release signal is given. 7. A lock release as claimed in Claim 6 in which the lock comprises a mechanical bolt engaging a recess and electrical driven release means to withdraw the bolt in the event that the said resulting tones output corresponds with the preset data. 8. A lock release for a closable and lockable compartment in a piece of furniture, substantially as herein described with reference to the accompanying drawings. 9. A piece of furniture having a lockable compartment closed by a lock release as claimed in any of claims 6 to 8.

Inventors: YAMASHITA TOSHIHIKO, YAMASHITA, TOSHIHIKO
Applicants: UNIQEY HK LIMITED, UNIQEY HK LTD
Application year: 1990
Main classification: E05B49
IPC codes: G07C9