BABY MONITOR WITH TRANSMISSION OF AUDIO AND TEMPERATURE SIGNALS

Abstract: It is common to employ a baby monitoring device - a sound tranceiving apparatus, with a microphone/transmitter in the child's room coupled to a loudspeaker/receiver carried by or located adjacent a Parent, so that any noises the child makes are instantly transmitted to and received by the Parent. The transmitter and receiver are usually coupled either inductively or electromagnetically - in the latter case, by radio (usually Very High Frequency [VHF] radio of only a short range). Paediatricians nowadays consider that an important factor in a very yound child's life is the ambient temperature, and thus it is therefore necessary for the ambient temperature of the child's room to be taken into account, and for the appropriate changes to be made if the temperature rises or falls beyond suitable limits. The invention seeks to render this task easier by providing up-to-date information about the room temperature. More specifically, it proposes that at regular and frequent intervals the monitoring equipment uses an associated temperature sensor to provide a temperature-indicating output which is transmitted (over a sub-carrier) to the receiver and there displayed by appropriate display means for the Parent to see and act upon.

Description: BABY MONITOR WITHTRANSMISSION OF AUDIO AND TEMPERATURE SIGNALS This invention concerns monitors, and relates in particular to devices allowing the monitoring at a distance of a baby in its room. It is common for babies beyond a certain age - six or so weeks, for example - and infants to have their own room (the nursery) in which they sleep and play. In many households it may be possible for the child's mother or father, or whoever is minding the child, to be near enough to hear any noises, particularly cries, that the child may make, or so frequently to visit the child that no more than a few minutes will pass between the child beginning to cry and the Minder coming to see it. In other households, though, this is more difficult, or is somewhat inconvenient, and so it is common for there to be employed some sort of baby monitoring device - a sound transceiving apparatus, with a microphone/ transmitter in the child's room coupled to a loudspeaker/receiver carried by or located adjacent the Minder - so that any noises the child makes are instantly transmitted to and received by the Minder, who can then go and investigate what, if anything, is wrong with the child. The transmitter and receiver can be linked by wire, or other physical connection, but it is most usual these days for them to be coupled either inductively or electromagnetically - in the latter case, by radio (usually Very High Frequency [VHF] radio of only a short range) - both to permit the receiver to be placed anywhere suitable in the building without trailing unsightly wires behind it and also to allow the Minder to move about in the building carrying the receiver free of the encumbrance of those same wires. Paediatricians nowadays consider that an important factor in a very young child's life is the ambient temperature, for the bodies of small children - and especially new babies - have not yet achieved the good, automatic temperature control possessed by adults. It is desirable that a baby be kept warm, but not too warm - that when asleep it be protected by blankets and other bed clothes if the room's temperature is low, but that it should not be covered by so many layers that it become too hot if the room temperature should rise. It is therefore necessary for the ambient temperature of the child's room to be taken into account, and for the appropriate changes to be made - either to the heating or to the baby's coverings - if the temperature rise or fall beyond suitable limits. The invention in its most preferred forms seeks to render this task easier by providing the child's Minder with up-to-date information about the room temperature. More specifically, it proposes that at regular and frequent intervals the Minder should be advised of the room temperature by apparatus forming an extension, as it were, of the normal monitoring equipment, this being one wherein associated with the transmitter is a temperature sensor that provides a temperature-indicating output which, much like any output from the monitor's microphone, is transmitted to the receiver and there displayed by appropriate display means for the Minder to see and act upon. Of course, the temperature is only one sort of data that might be transmitted along with the noises made by the child - other data types could include limit settings, clock pulses, respiration rates, and the like. The invention proposes that all this data be transmitted to the receiver using a VHF radio link with a sub-carrier modulated by the data. The data code strings can be pulse modulated with a sub-carrier frequency low enough in practice to be virtually inaudible to the recipient; this is an inexpensive and cost-effective way - in a product of limited performance - of transmitting data as a background signal without noticeably affecting normal voice transmission/ reception. In one aspect, therefore, the invention provides child-monitoring apparatus enabling the Minder of a child to hear what noises are made in the child's room, the apparatus being of the type having a microphone and transmitter (to be placed in the child's room) and, operationally linked thereto, a receiver and speaker to be positioned adjacent the Minder's location, which apparatus also includes associated with the transmitter data-generating means the data from which is transmitted to the receiver, and in which apparatus the microphone and transmitter are operationally linked to the receiver and speaker by a short-range VHF radio link utilising a sub-carrier modulated by the transmitted data. The invention provides child-monitoring apparatus of the type having a microphone and transmitter (as a single module) operationally linked to a receiver and speaker (again, as a single module: this may possibly be portable, and carried/worn by the Minder). These components may be of any suitable variety. The apparatus may also include other features appropriate to a child monitoring device, such as: a sleep mode (when either or both the transmitter and receiver are powered down, and do not communicate one with the other); a diagnostic testing ability (for checking that the various alarms etc are actually working); an out-of- range warning ( for when the minder moves too far from the transmitter); a visible warning of the child crying (typically a row of Light Emitting Diodes [LEDs], on the receiver module, more of which light as the crying increases in amplitude); and, if battery-powered, a "battery low" warning. An instance of a typical such transceiver apparatus presently available on the market is that made by Playskool and sold under the name ROAMER III. The apparatus of the invention includes, associated with the transmitter, data-generating means the data from which is transmitted to the receiver. Very preferably one of these data-generating means is a temperature sensor that provides a temperature- indicating output. The sensor may be of any suitable type - for example, it may be a thermistor type - and its output (which is transmitted to and displayed upon display means associated with the receiver) is most preferably shown, advantageously by a small LCD screen, on the transmitter module, so that when in the room the Minder can check the room's temperature simply by referring to the module's display. It is desirable that the temperature display be switchable between Centigrade/Celsius (°C) and Fahrenheit (°F). Although such a child-monitoring apparatus will be used primarily indoors, with the child in its room, it is possible that a similar set-up might be required for a child outdoors in its pram. A temperature sensor suited for indoor use might not be appropriate for outdoor use, so it might be desirable for the apparatus - 5 - to include two sensors, one for indoors and one for outdoors, suitably switched. The data-generating means output is transmitted to the receiver using a VHF radio link, and providing a sub-carrier modulated by the data. In one convenient version of that technique, the data code strings are pulse modulated with a sub-carrier frequency low enough either to be virtually inaudible to the human ear or to be unreproduceable with the relatively low fidelity speakers employed; a typical frequency is 80Hz. Using appropriate circuitry this sub-carrier is then mixed with the voice signal, and the resultant mixed signal is FM modulated and transmitted using the RF link. A typical frequency for that link is one in the 30 to 70MHz range, say around 50MHz . This utilisation of a sub-carrier is, compared with other methods, an inexpensive, cost-effective way in a product of limited performance of transmitting data as a background signal without noticeably affecting normal voice transmission/ reception. The primary data is temperature, and the transmission of this data can be continuous - that is to say, non-stop - but it will normally be necessary only to send the data at regular but relatively infrequent intervals. For example, it might be transmitted no more often that every five minutes. Another possibility, though, is to compare the present temperature with whatever it was a short time - say, 30 seconds - ago, and to transmit the current information if, and only if, it is actually different from what it was then. A third possibility is for the transmission to be voice activated - that is, or a cry or other sound from the child to trigger the transmission of the present temperature data. And, of course, all three of these could be employed. Desirably the apparatus of the invention will be able to record - most conveniently in the transmitting module - the maximum and minimum temperature it detects. In the invention ' s apparatus the transmitted temperature information is displayed upon display means associated with the receiver. Like the display on the transmitter module, the receiver module display is conveniently an LCD display, and is most desirably switchable between °C and "F. It may be advantageous for the Minder to be able to set the transceiver apparatus of the invention to provide not merely a display of the temperature in the child's room but in addition some sort of visible or audible warning if the temperature goes up (or down) beyond certain predetermined limits. In such a case, then, the apparatus - and preferably the receiver section thereof - conveniently includes both programming means and warning means that together first permit the Minder to set upper and lower limits, and then provide the relevant warning - a buzzer, say, or a flashing light - if the actual room temperature goes up or down beyond the pertinent limit. The sub-carrier technique can usefully be employed to carry these other data signals - for example, realtime clock data, temperature scale (Centigrade or Fahrenheit) information, timer alarm status, battery level status, high/low temperature recorded data, high/low temperature alarm limits, and alarms on/off status, as is shown in the accompanying Drawings. An embodiment of the invention is now described, though by way of illustration only, with reference to the accompanying Drawings in which: Figure 1 shows a block schematic diagram of a transmitting module - the baby unit - of the baby-monitoring apparatus of the invention; and Figure 2 shows a block schematic diagram of a matching receiving module - the mother unit - of the baby-monitoring apparatus of the invention. In the transmitting module the components are as follows : - MCU. This is a single chip microprocessor which controls all the input and output signals, and also drives the LCD display and the alarm signal outputs. INSIDE/OUTSIDE SENSOR. Each of these is a temperature sensor that uses a thermistor for measurement. MIC -AMP. This is an amplifier that effects voice amplification to an appropriate level with gain control. VOICE ACTIVATE. This is to hold and compare the microphone signal, and output a control signal to trigger tone generator I and power switch. TONE GENERATOR I . This generates a 90Hz tone signal when triggered by the voice activate control . TONE GENERATOR II. This generates a 135Hz tone signal, and is controlled by the MCU data signal. CRYSTAL OSC & MODULATION. The signal frequency is modulated with the crystal oscillating frequency. FREQ. MULTIPLIER. This multiplies the fundamental frequency to the third overtone carrier frequency. R.F. AMP. This amplifies the carrier frequency, and outputs it to the antenna. POWER SWITCH. This is a transistor power switch which controls the R.F. transmission. In the receiving module the components are as follows:- MCU. This is a single chip microprocessor which can receive all input data and output it to an LCD display and buzzer alarm. R.F. AMP. This receives the radio frequency from the antenna, and performs amplification. MIXER. This mixes the local oscillations with the carrier frequency. I.F. AMP. This uses a narrow band I.F. IC for amplification, and outputs the recovered audio signal. TONE DETECTOR I. This uses a two-state tone filter to detect out the tone signal and convert it to a DC voltage. TONE DETECTOR II. This uses a two-state tone filter to detect out the data tone signal and convert it to DC levels. COMPARATOR. This compares the input signal voltage with the preset level, and performs output control. POWER SWITCH. This is a transistor switch which controls the on/off state of the audio amplifier. AUDIO AMP. This is to amplify the audio signal, and provides volume control, and outputs it to the speaker. BAR GRAPH. This amplifies the audio signal and drives the sound level LEDs . The operation of the apparatus is as follows :- Transmitter (baby unit) 1) This uses a 4-bit OKI MSM64152 MCU for temperature measurement and recording, timing and data output control. It can directly drive the LCD display with 4-8 digits with 4 mux multiplexing. The temperature recording range is from -20°C to +50°C, and the resolution is 0.1°C (or °F) . The data sent-out rate is 10 bits/sec, data refresh rate per 15 to 20 seconds. The alarm signal beep tone is 0.2 sec on, 2 sec off. 2) All data can be transmitted to the receiver (the mother unit) through a radio link. In the transmitter (the baby unit) a 135Hz tone signal is used with tone switching on and off to simulate the timing. Data-enable pin from the MCU controls the period for data transmission. The voice signal is received through the microphone, and after amplification is sent for modulation, and passed to the voice-activate circuit. Another 90Hz tone signal is used for audio signal transmission. All the signals are modulated at the variable capacitance diode (vcd) with crystal oscillation. After being multiplied to the carrier frequency the signals are send to R.F. amplification, and then go to the antenna. Receiver (mother unit) 1) This uses a 4-bit OKI MSM64152 MCU for data processing, driving the LCD, and displaying the temperature status, and the out-of-range alarm signal . 2) In the receiver (the mother unit) the voice- and data-modulated carrier frequency is received from the antenna, and sent to an R.F. amplifier for amplification. It is then mixed with the crystal frequency, and the audio component extracted and amplified. Another part of recovered audio signal is sent to the tone detector stage; at tone detector I the tone signal is filtered out at sinusoidal form and sent to the comparator, and after comparison the comparator outputs a control voltage to switch on the power supply to the audio amplifier, whereupon audio sound can be heard from the speaker. At tone detector II, the on/off data tone signal is recovered in DC level and sent directly to the comparator. The data chain is then sent to the MCU's input port for data processing, and for displaying the status.

Claims: CLAIMS 1. Child-monitoring apparatus enabling the Minder of a child to hear what noises are made in the child's room, the apparatus being of the type having a microphone and transmitter (to be placed in the child's room) and, operationally linked thereto, a receiver and speaker to be positioned adjacent the Minder's location, which apparatus also includes associated with the transmitter data-generating means the data from which is transmitted to the receiver, and in which apparatus the microphone and transmitter are operationally linked to the receiver and speaker by a short-range VHF radio link utilising a sub-carrier modulated by the transmitted data. 2. Apparatus as claimed in Claim 1, wherein the data- generating means is or includes a temperature sensor that provides temperature-indicating output data, and this temperature data is transmitted to and displayed upon display means associated with the receiver. 3. Apparatus as claimed in Claim 2, wherein the temperature sensor that provides a temperature- indicating output is a thermistor type. 4. Apparatus as claimed in either of Claims 2 and 3, wherein the temperature sensor's output is transmitted to and displayed upon LCD screen display means associated with the receiver. 5. Apparatus as claimed in any of Claims 2 to 4, wherein the receiver's temperature display is switchable between Centigrade/Celsius (°C) and Fahrenheit ( C F). 6. Apparatus as claimed in any of Claims 2 to 5, wherein the transmission of temperature data is either: continuous; effected at regular but relatively infrequent intervals; effected only if it is actually different from what it was a predetermined time earlier; or upon voice-activation. 7. Apparatus as claimed in any of Claims 2 to 6, wherein in the transmitting module there can be recorded the maximum and minimum temperature detected. 8. Apparatus as claimed in any of Claims 2 to 7, wherein the transceiver apparatus includes means to provide a visible or audible warning if the temperature goes up (or down) beyond certain predetermined limits. 9. Apparatus as claimed in any of the preceding Claims, which also includes one or more of the following: a sleep mode; a diagnostic testing ability; an out-of-range warning; a visible warning of the child making a noise; and if battery-powered, a "battery low" warning.

Inventors: GOOCH DAVID, LIU CHI CHEUNG, GOOCH, DAVID, LIU, CHI, CHEUNG
Applicants: GOOCH DAVID, KINDERTEC LTD, LIU CHI CHEUNG, GOOCH, DAVID, KINDERTEC LTD., LIU, CHI, CHEUNG
Application year: 1997
Main classification: G08B21
IPC codes: G01K1, G08B21