GB2533542A

GB2533542A - Pet door control system

Info

Publication number: GB2533542A
Application number: GB1409375.1A
Authority: GB
Inventors: Oates Jeremy
Original assignee: Pet Mate Ltd
Current assignee: Pet Mate Ltd
Priority date: 2014-05-27
Filing date: 2014-05-27
Publication date: 2016-06-29
Also published as: GB201409375D0

Abstract

A detection system for a pet flap comprises a processor, a light generator, and a light detector arranged so that interposing of an animal body interrupts a path between the light generator and light detector changing the output of the light generator, the light detector including a processor. The system may use infra-red LEDs and detectors. A first light detector value 40 is taken is when the light generator is inactive, then a second light detector value 41 is taken when the light generator is active. These values are used to calculate a compensated value Vcomp 42 which accounts for ambient light falling on the detector, and this compensated value is compared with threshold values in order to determine whether a pet is present in the pet flap.

Description

PET DOOR CONTROL SYSTEM

The present specification relates to a pet door control system, particularly the maintaining of the detection performance of the presence of a pet.

A popular type of cat flap controls which cats may be allowed to enter by identifying a unique chip on the cat, usually an REID chip that may be carried on a fob, or increasingly an implanted REID chip. The REID reader is triggered to seek and interrogate an RFTD chip by the detection of the presence of a cat in the cat flap tunnel. A known method of detecting the presence of a cat is to transmit a beam of infra-red light (usually using an infra-red LED) across the tunnel, so that the beam hits an optical detector. One configuration Is is to position the infra-red LED and the optical detector on the upper inner surface of the tunnel, so that when the tunnel is empty, the light beam from the infra-red LED is reflected by the bottom of the tunnel onto the optical detector. The presence of a cat (or other object) interrupts, scatters or reflects the light beam so that the signal is altered by the time it gets to the detector; the light level may be diminished, but depending on the cat and its position, the light level may be increased. This change triggers the cat flap control to seek the presence of an REID chip, and identify it, using an RF transmitter and receiver circuit and aerial.

Many IR optical detectors are sensitive to infra-red light, but also respond to some degree to visible light and other non-1R wavelengths. Often, the optical detector includes a filter is used that is transparent to infra-red light, but attenuates other wavelengths. Usually then, other wavelengths falling on the TR optical detector are filtered out and do not affect the TR optical detector readings. However, sunlight can produce such an intense visible light, that even after attenuation by the filter, the change in the light signal due to the presence of a cat can be difficult to detect.

The optical detector output is typically routed through an analogue to digital converter, Referring to figure 3a, the cat flap control is set such that an optical 1() detector output between rILD and V-LD are counted as logical 0, corresponding to the absence of a cat. An optical detector output above V1LD or below 17-LD in contrast equates to a logical 1, corresponding to the presence of a cat or other object.

V+LD and Vin are values + LD above a value VT,ED which corresponds to a typical output detector value. The optical sensor output is read while a short pulse of infra-red light is emitted from the infrared LED. When no significant ambient light is falls on the cat flap, and the path between the LED and the optical sensor is unobstructed, the optical detector output signal 30 is ViLD.

Referring to figure 3b, when the path between the LED and the optical sensor is obstructed, for example by the presence of a cat (again with no ambient light present), the optical detector output signal 31 falls to Tc",. It should be noted though that the output value in the presence of a cat, depending on the cat's coat, its position in the cat flap, and the type and configuration of the cat flap, can result in an increase of the output value.

Usually, the signal from the infra-red LED is so high compared to ambient light that the optical detector can easily detect changes in the output due to the presence of a cat or other object in the cat flap.

Referring to figure 3c, in bright sunlight a large amount of ambient light increases the optical sensor output 32 by a value c/1 compared to the situation in figure 3b when the tunnel is obstructed, to a value sun. It will be seen then that the alteration by value 6E1 in the presence of bright light makes it harder to detect changes associated with the presence of a cat in the cat flap tunnel, and a logical 0 will be returned when a cat is present in the cat flap tunnel. in such a case, the system does not detect that a cat is in the cat flap tunnel, and does not initiate the RFID interrogation and will not allow any cat through.

The optical detector may be fitted with a higher quality filter that more effectively excludes visible light, but this increases the cost.

The object of the present invention is to provide a control element which mitigates these problems.

According to the present invention, there is provided a control element according to claim 1.

The principles of the invention can be applied to many shapes and designs of cat flap, so the cat flap is here illustrated diagrammatically.

The invention will now be described, by way of example, with reference to the drawings, of which Figure 1 is a perspective diagrammatic partial view of a cat flap; Figure 2 is a diagrammatic view of the components; Figures 3a to 3c show the optical detector outputs of the cattlap under particular circumstances; Figure 4 is a flowchart of the process; Figure 5 show the optical detector outputs and the correction due to the process; Figure 6 is a flowchart of another embodiment of the process; and Figure 7 show the optical detector outputs and the correction due to the time variation; Referring to figure I, a cat flap includes an inner frame 10, into which are incorporated an infra-red LED 12 and an infra-red optical detector 13. The inner frame comprises an upper panel 15, a lower panel 16, and two side panels 17, 18. This inner frame forms at least part of a cat flap tunnel, the remainder of the cat flap housing and door not being here illustrated.

The infra-red LED 12 and the infra-red optical detector 13 are positioned on the upper panel 15 of the inner frame 1 a When the infra-red LED 12 is operated, without a cat or other object occupying the tunnel of the cat flap, a beam of infra-red light is transmitted from the infra-red LED 12 towards the 5 lower panel 16, where it is reflected upwards and onto the infra-red optical detector 13, which detects the strength of the light falling on it. The path of the infra-red light beam is illustrated here by an arrow a; however, it will be realised that the infra-red LED 12 need not transmit a tightly focused beam, and thither, the reflection from the lower panel 16 may be of a diffuse or 10 scattered nature. The arrow a merely illustrates a possible path for some of the reflected light.

When a cat is present in the tunnel of the cat flap, and the infra-red LED 12 is operated to transmit a beam of infra-red light, the beam is interrupted by the 15 body of the cat, and either absorbed or reflected so that little or none of the infra-red light reaches the infra-red optical detector 13.

Referring to figure 2, the electrical subcomponents of the catflap control comprise a CPU 20, the infra-red LED 12, the infra-red detector and analog to digital converter 13, the REID reader 26, and the door latch control 28. This is a purely diagrammatic representation, and it will be realised that the processing and logic functions of the circuitry, and other circuitry components, may be distributed and configured in different but equivalent ways.

Referring to figure 4, CPU turns on 21 the optical detector 13. The optical detector 13 includes an analog to digital converter, which is turned on and off with the optical detector. The output of the optical detector is also fed directly to the CPU and the operation of the analog to digital convertor is further controlled by the CPU as will become apparent in the following description.

The optical detector and the analog to digital converter take some time to settle, so the system pauses 22 to give these components a time to start to function. Once this waiting period has elapsed, the optical detector takes a reading 23, this light level reading value being 1,1"/",it bght I. The infra-red LED is then turned on 24 and a further reading is taken 25 by the optical detector, this light level reading this light level being VIR LED on. The infra-red LED is then turned off 26, the amount of time the infra-red LED having been on for being a comparatively short pulse in order to conserve the cat flap's battery. Finally, the optical detector and the analog to digital converter are turned off Figure 5 shows the optical sensor values for the T:"7,/,"",/,(0" 40 and VIR LED on 41. The value of FIR LhD " 41 is equal to the value of TIED due solely to the LED plus the value d due to the ambient light 14b2", kg& . The CPU calculates a new value 42 corresponding to the ambient light by subtracting kramtuent Eglit 1 40 from FIR LED " 41. This new value IT"",, 42 compensates for the effect of ambient light falling on the optical sensor. The value IT"",, 42 can then be compared to the threshold values 11-+LD and TT-LD to determine whether or not a cat is present in the cat flap tunnel.

It will be noted that the value of ki,"71"", Egi, 1 40, by measuring the actual ambient light each time a reader is taken, compensates for the ambient light in any conditions, whether the optical sensor is operating at night, twilight, an overcast day or in full sun. In this and the other embodiments, the compensation is here shown being applied to an optical sensor reading taken when no cat or other object is present in the cat flap tunnel, and the same compensation is applied to the optical sensor reading produces when a cat or other object is present in the tunnel.

Referring to figure 6, a further step may be advantageously added to the process described above in relation to figure 4. After the reading V m LET) "". has been taken and the infra-red LED is then turned off 26, a further reading if ambient fixi" 2 27 is taken by the optical sensor, Then, as for the previously described process, the optical detector and the analog to digital converter are turned off 29.

The sensitivity and responsiveness of the optical sensor and the analog to digital converter 13 takes some time to settle. It may be that it is not practical or possible to wait until the optical sensor and the analog to digital converter 13 is fully responsive in a constant manner; since keeping the circuit for a short time each cycle on represents a considerable increase in power requirements.

Referring to figure 7, the responsiveness (with time) of the optical sensor and the analog to digital converter light levels corresponding to the IR LED being on, and the ambient light level, is shown by two curves 53, 54. It will be appreciated that these curves are simply representative, and dependent upon the particular components and configuration.

The three optical sensor readings of I"'"""/".",,,/, 50, I/7R LFT) "". 51, and krainInent light 2 52 are taken at equally spaced intervals tO, tl, t2. It will be seen that the responsiveness of the optical sensor is increasing from tO to t2. Provided that the responsiveness curve is approximately linear however, the average value of Famhe", light I and I7"."1""/"."g",2 will be close to the value of the ambient light had a reading been taken at ti.

The CPU then calculates a new value 1,1",,," 42 according to the calculation: Vcomp = ITIR LED on - Vim 1»ent light] ± ram burnt light 2) This new value Ico, compensates for the effect of ambient light falling on the optical sensor even when the responsiveness of the optical sensor varies with time As before, the value Vcomp 42 can then be fed into the analog to digital converter and compared to the threshold value V7 to determine whether or not a cat is present in the cat flap tunnel.

Ideally this procedure is carried out for every reading; however, the ambient light value or values may be stored in a memory and used to modify or compensate for subsequent readings where just a single optical sensor reading is taken when the IR LED is on. Also, less ideally, two LED or more readings may be taken either side of an ambient light reading, and the average of the LED readings used. Also, further averaging and compensation methods could be applied to the values.

In some cat flaps, rather than an average light signal reading, and a monitoring of a change of light level, the configuration may be that a comparatively focus beam of light is interrupted, so that the presence of a cat will always result in a lower signal. This system could still be applied in such a case.

Claims

Claims 1. A detection system for a pet flap comprising a processor a light generator a light detector arranged so that interposing of an animal body interrupts a path between the light generator and light detector changing the output of the light generator to the light detector producing a processor comprising the steps of taking a first light detector value is when the light generator is inactive, taking a second light detector value when the light generator is active, reducing the second light detector value according to the value of the first light detector value to give a compensated light value using this compensated value to modify the value of a light detector value in order to determine whether a pet is present in the pet flap.
2. A system according to claim 1 wherein the second light detector value is taken after the first light detector value.
3. A system according to any previous claim wherein the first light detector value is subtracted from the second light detector value.
4. A system according to any previous claim wherein a third light detector value is taken when the light generator is inactive.
5. A system according to any previous claim wherein an average value of the 5 first light detector value and third light detector value is subtracted from the second light detector value.
6. A system according to any previous claim wherein a plurality of light detector values are taken when the light generator is inactive, and a 10 compensated value determined on the basis of an average value of the readings wherein different readings are weighted.