GB2344201A - Apparatus for door entry control and/or door entry request indication - Google Patents

Abstract

In apparatus for door entry control or door entry request indication, there is a transmitter and a receiver. The transmitter includes a transmitting antenna A1. The receiver includes a receiving antenna. At least one of the transmitting antenna A1 and receiving antenna consists of a conductive member defining an aperture e.g. slot. The conductive member can be part of a metal casing of the transmitter or receiver.

Description

APPARATUS FOR DOOR ENTRY CONTROL AND/OR DOOR ENTRY REOUEST INDICATION The present invention relates to apparatus for door entry control and/or door entry request indication comprising a transmitter and a receiver, and also relates to the transmitter and the receiver.

Known wire free door entry systems consist of two distinct parts; the transmitter and the receiver. When the transmitter is activated, it transmits a coded radio signal. The receiver receives and decodes the coded signal and acts to electronically control a lock or sound broadcast unit in a pre-programmed manner. The result of this sequence may be the opening of a door or the sounding of a chime, for example.

Use of internal and external antennas are known in wire free door entry systems, although in current practice it has become more common to use internal antennas at both the transmitter and receiver for aesthetic reasons. The use of internal antennas requires that the outer casings of both the transmitter and receiver be of a non-conductive material. Known antennas are typically simple short wire monopoles or metallic traces on the device circuit board; although other structures are known, such as aperture antennas, for example, of slot or circle shape, such as described in Stutzman, Warren L; Thiele Gary A."Antenna Theory And Design"John Wiley & Son 1981, and Balanis, Constantine A."Antenna Theory Analysis And Design"John Wiley & Son 1982.

The present invention provides apparatus for door entry control and/or door entry request indication comprising a transmitter and a receiver, the transmitter including a transmitting antenna operative to transmit over air a signal representative of a door control command and/or a door control request, and the receiver including a receiving antenna operative to receive over air the signal representative of the door control command and/or door control request, in which at least one of the transmitting antenna and the receiving antenna is of the type comprising a conductive member defining an aperture.

Preferably, there is an outer casing which at least partially covers the transmitter or receiver, the outer casing comprising the conductive member.

This type of antenna has clear advantage in a door entry system in which metal casings are required, for example to prevent tampering due to their greater strength. Any aperture in the casing is usable as an antenna, a situation which applies to both transmitting and receiving ends of the over air (wire free) link.

Preferably the slot is filled with a non-conductive filling to prevent environmental damage such as water ingress.

The present invention also relates to a transmitter a transmitter including a transmitting antenna operative to transmit over air a signal representative of a door entry command and/or a door entry request to a receiver which enables door entry and/or indicates the door entry request, the transmitting antenna comprising a conductive member defining an aperture.

The present invention also relates to a receiver including a receiving antenna operative to receive over air a signal representative of a door entry command and/or door entry request from a transmitter and to control door entry and/or indicate the door entry request, the receiving antenna comprising a conductive member defining an aperture.

Preferred embodiments of the present invention will now be described by way of example and with reference to the drawings, in which: Figure 1 is a schematic diagram of a transmitter of a first embodiment; Figure 2 is a circuit diagram of the signal generator M1 of the transmitter of the first embodiment; Figure 3 is a schematic diagram of a transmitter according to a second embodiment; Figure 4 is a schematic diagram of a transmitter according to a third embodiment; Figure 5 is a schematic diagram of a receiver according to a first embodiment; Figure 6 is a circuit diagram of signal processor R1 of the receiver according to the first embodiment, and Figure 7 is a schematic diagram of a receiver according to a second embodiment, and Figure 8 is a schematic diagram of a receiver according to a third embodiment.

The transmitter can be, for example, any of those described below. Upon activation of a simple switch mechanism, the transmitter produces a modulated RF signal which is radiated by the slot antenna embodied in the conducting enclosure. When the modulated RF signal radiated by the slot of the transmitter impinges upon the slot in the enclosure of a receiver which can be, for example, any of those described below, a voltage is developed in the slot of the receiver. This signal is processed to provide a control signal to either control a loudspeaker or other noise generator to produce a noise indicating that the switch connected to the transmitter has been activated, for example by someone wanting to gain entry, and/or to electronically control a lock operative to unlock a door.

Transmitter As shown in Figure 1, in a first embodiment the transmitter consists of a signal generator M1 connected via an unbalanced to balanced transformer ("balun") T1, of suitable impedance transfer ratio, to an antenna A1. The antenna A1 consists of a conducting enclosure B1 in which a slot S1 is located.

In other embodiments, an aperture of another shape can replace the slot, for example a circular aperture or aperture of a fractal geometry.

The slot or other aperture is preferably filled with nonconductive filling to prevent water ingress.

The signal generator M1 has an unbalanced amplitude modulated radio frequency output signal OP1 which is applied to the balun T1. The balun T1 facilitates efficient power transfer between the generator MI and slot S1. In the present embodiment it is passive; in alternative embodiments it can be active. The balun Ti operates to convert the output signal OP1 to a balanced signal OP2 which is applied directly to any two points on the slot S1, such as on opposite sides, causing the slot S1 to radiate a radio frequency signal over air.

The construction of the signal generator M1 is shown in more detail in Figure 2. In the signal generator M1, resistor RE1, resistor RE2, inductor L1, transistor Q1, and SAW Resonator RS1 form an oscillator circuit producing a radio frequency signal. In this embodiment the frequency of the radio frequency signal is controlled by the SAW Resonator RS1. In other embodiments, other frequency control means can be used. Inductor L2 and capacitors Cl and C2 are configured so as to be operative to ensure that power is efficiently transferred from the oscillator circuit RE1, RE2, L1, Q1, RS1 to the balun T1.

Collectively components L2, Cl and C2 constitute a matching network. In other embodiments, other configurations of matching network are known.

The signal generator M1 further comprises a control means U including a switch Si which when closed results in control means U providing a code at output port 0. The code from output port 0 is provided to transistor Q2 which acts as an electronic switch, being turned on and off by the presence or absence of the code at output port 0.

Turning transistor Q2 on or off switches the supply voltage V+ applied to the oscillator circuit RE1, RE2, L1, Q1, RS1 thereby turning the oscillator circuit on or off, thereby producing an amplitude modulated radio frequency signal OP1. In other embodiments, the code at output port O can be used to frequency modulate the generated radio frequency signal.

As shown in Figure 3, in a second embodiment, the transmitter comprises a signal generator M1, conducting enclosure B1 and slot Sl as in the first embodiment; however, the balun T1 is replaced by a physical balun, namely an additional slot S3 at the midpoint along the length of the slot S1, the additional slot S3 lying transverse to slot S1. In use the unbalanced output signal OP1 is applied to the end of the additional slot S3 distal from slot S1. The length of the additional slot S3 is selected so as to have a balancing effect on the signal applied to S1. Various other geometries for the physical balun S3 are possible in other embodiments, by varying the geometry of the aperture S1, S3.

As shown in Figure 4, in a third embodiment, the transmitter comprises a signal generator M1, conducting enclosure B1 and slot S1 as in the first embodiment, the output OP1 of which is provided to the base of transistor Q2. Transistors Q2 and Q3, inductors L3 and L3, resistor RE3 and capacitor C3 constitutes a differential amplifier and there can be biasing components (not shown). This differential amplifier can be considered to be a balun, in particular of active electronic type. The output signals from the collectors of transistors Q2 and Q3 together constitute a balanced output signal OP2, which is an amplitude modulated radio frequency signal. The output signal from each transistor Q2, Q3 is applied to a respective point on the slot S1 causing the slot S1 to radiate a radio frequency signal over air.

In a further embodiment, there is no balun and the signal generator is connected directly to the antenna slot, the output signal from the signal generator being balanced. In an alternative embodiment, a balun is included as a balanced to balanced impedance transformer to facilitate impedance matching (rather than balancing) and so increase the efficiency of power transfer from signal generator M1 to antenna A1.

Receiver As shown in Figure 5, in a first embodiment the receiver includes a conducting enclosure B2 having a slot S2, and a balun T2 all of similar structure to that of the transmitter as shown in Figure 1. In other embodiments, an aperture of another shape can replace the slot S2, for example a circular aperture or aperture of a fractal geometry.

The slot or other aperture is preferably filled with nonconductive filling to prevent water ingress. The receiver also includes a signal processor R1 operative to demodulate and process a receiver radio frequency signal, the output of which is in some embodiments, data requiring further processing, or in other embodiments, a signal suitable for direct application to the chime sounder in the case of a wire free door chime system or electronic activation mechanism of a lock in the case of a wire free entry system.

In the first embodiment which is shown in Figure 5, the signal processor R1 has an unbalanced input IP2. An electromagnetic field applied to the slot S2 which is embedded in a conducting enclosure B2 excites a balanced voltage IP2 across the slot S2 which converted to an unbalanced signal IP1 by the balun T2 which is suitable for application to the signal processor R1. In the present embodiment the balun is passive; in alternative embodiments it can be active.

Figure 6 shows the input stage (i. e. part) of the preferred signal processor R1. The stages (not shown) following this input stage depend upon the nature of the modulation (Amplitude Modulation or Frequency modulation for example) produced by the signal generator M1 of the transmitter and the type of the signal processor R1 (Superregenerative or Superhetrodyne for example). The input stage shown in Figure 5 is unbalanced, and biasing components (not shown) can be present. T2 is the Balun transformer converting the balanced voltage ip2 developed by the slot S2 antenna to an unbalanced voltage IP1. Inductor L5 and capacitors C5 and C4 together form a matching network with a bandpass frequency response, although other configurations and frequency responses are used in other embodiments. These matching network components L5, C5, C4 ensure that the unbalanced output of the Balun T2 is transferred with maximum efficiency to the input of the signal processor R1, in this case via the base of transistor Q4.

As shown in Figure 7, in a second embodiment, the receiver consists of a signal processor R1, conducting enclosure B2 and slot S2 as in the first embodiment; however, the balun T2 is replaced by a physical balun, namely an additional slot S4 at the midpoint along the length of the slot S2, the additional slot S4 lying transverse to slot S1. The length of the additional slot S4 is selected so as to have a balancing effect. The balanced output signal IP2 is received at the end of the additional slot S4 distal from slot S2. Various other geometries for the physical balun S4 are possible in other embodiments, by varying the geometry of the aperture S2, S4.

In a third embodiment of the receiver, shown in Figure 8, the signal processor R1'has a balanced input IP1, in which case the output voltage IP1 developed by the slot S2 is applied directly to the signal processor R1.

As shown in Figure 8, the input stage (i. e. part) of the signal processor R1 consists of a pair of transistors Q5 and Q6 act as a differential pair differential amplifier having a balanced input IP1. The balanced voltage IP1 developed by the slot S2 antenna A2 is applied to the bases of the transistors Q5 and Q6 without a Balun Transformer T2. The output of this balanced input stage is applied to the following stages in either a balanced or unbalanced configuration using either both or only one of the collectors of the differential pair Q5, Q6. The transistors Q5 and Q6 can thus act as a balun of active electronic type.

In a further embodiment there is no balun and the antenna slot is connected directly to the signal processor, the output signal from the antenna slot being balanced. In an alternative embodiment, a balun is included as a balanced to balanced impedance transformer to facilitate impedance matching (rather than balancing) and so increase the efficiency of power transfer from the antenna A2 to signal processor R1.

Claims (19)

1. CLAIMS : 1. Apparatus for door entry control and/or door entry request indication comprising a transmitter and a receiver, the transmitter including a transmitting antenna operative to transmit over air a signal representative of a door control command and/or a door control request, and the receiver including a receiving antenna operative to receive over air the signal representative of the door control command and/or door control request, in which at least one of the transmitting antenna and the receiving antenna is of the type comprising a conductive member defining an aperture.
2. 2. Apparatus according to claim 1, in which there is an outer casing which at least partially covers the transmitter or receiver, the outer casing comprising the conductive member.
3. 3. Apparatus according to claim 1 or claim 2, in which the casing is of metal or metal alloy and at least substantially covers the transmitter or receiver.
4. 4. Apparatus according to claim 1,2 or 3, in which the aperture comprises a slot.
5. 5. Apparatus according to any of claims 1 to 4 in which the aperture is filled with a non-conductive filling.
6. 6. Apparatus according to any preceding claim, in which the receiver comprises a lock for a door.
7. 7. Apparatus according to any preceding claim, in which the receiver comprises a sound generator operative to indicate a door entry request.
8. 8. Apparatus according to claim 7, in which the sound generator is a chime sound generator.
9. 9. A transmitter including a transmitting antenna operative to transmit over air a signal representative of a door entry command and/or a door entry request to a receiver which enables door entry and/or indicates the door entry request, the transmitting antenna comprising a conductive member defining an aperture.
10. 10. A transmitter according to claim 9, in which there is an outer casing which at least partially covers the transmitter, the outer casing comprising the conductive member.
11. 11. A transmitter according to claim 10, in which the casing at least substantially covers the transmitter and is of metal or metal alloy.
12. 12. A transmitter according to any of claims 9 to 11, comprising a signal generator connected to the transmitting antenna via a balun.
13. 13. A receiver including a receiving antenna operative to receive over air a signal representative of a door entry command and/or door entry request from a transmitter and to control door entry and/or indicate the door entry request, the receiving antenna comprising a conductive member defining an aperture.
14. 14. A receiver according to claim 13, in which there is an outer casing which at least partially covers the transmitter, the outer casing comprising the conductive member.
15. 15. A receiver according to claim 14, in which the casing at least substantially covers the receiver and is if metal or metal alloy.
16. 16. A receiver according to any of claims 13 to 15, comprising a signal processor connected to the receiving antenna via a balun.
17. 17. Apparatus for door entry control or door entry request indicators substantially as hereinbefore described with reference to the Figures.
18. 18. A transmitter substantially as hereinbefore described with reference to Figures 1 to 4.
19. 19. A receiver substantially as hereinbefore described with reference to Figures 5 to 8.