Abstract:
A toy including at least one capacitive sensor comprising a metal plate constituting one of the two plates of a capacitor, the second plate being constituted by a portion of a living being in the proximity of the toy, at least one effects generator; and a control circuit including means for causing effects to take place in response to stimulation of said capacitive sensor; the toy being characterized in that said metal plate of said at least one capacitive sensor is used as an antenna for picking up radio frequency transmission from said portion of a living being in the proximity of the toy.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of prior U.S. Non-Provisional patent application Ser. No. 11/571,789, which was the National Stage of International Application No. PCT/EP05/08208, filed Jan. 21, 2008, and entitled “Toy Sensitive to Human Touch,” which claims priority to French Patent Application No.  04 / 07655 , filed Jul. 8, 2004, the disclosure of each of the two above-identified applications is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a toy including means for detecting the approach of a portion of a living being, in particular for the purpose of triggering an effect, e.g. a sound effect, a light effect, or even a movement performed by said toy. More particularly, the invention relates to a doll including means for detection by the capacitive effect, combined with other detection systems. The field concerned is that of toys and the electronics in such toys. 
       BACKGROUND OF THE INVENTION 
       [0003]    It is known to use capacitive effect detectors for actuating effects in a toy such as a doll. The US patent application published under the No. US 2004/0043696 discloses a toy including a capacitive effect contactless detection system having a conductive receiver plate, an effect activation circuit, and means for interconnecting those two elements. The receiver plates can be hidden inside the toy so as to avoid any detection system being visible or apparent on the outside of the toy. When an object comes close to one of the receiver plates, the capacitance measured at that plate is modified. Consequently, by measuring the time constant of an RC circuit, equal to the product R×C where C is the capacitance of the plate and R is a resistance in the circuit, it is possible to detect variations in said time constant while discharging the RC circuit. The RC circuit discharge time is thus measured and then compared with a reference value in order to determine whether the capacitance has changed. Such a variation in the discharge time means that an object is in the proximity of the doll or the toy. 
         [0004]    However, if a metal plate is brought up to the toy, the toy detects the presence of the plate and therefore triggers its effects. The toy thus appears to respond even though no portion of a living being is in the proximity of the sensor. Such interference can be caused in this way by any nearby metal object of large weight or area. 
       SUMMARY OF THE INVENTION 
       [0005]    An objective of the present invention is to remedy the above-mentioned drawbacks. The invention thus proposes a detection system avoiding that kind of interference. It is based on the fact that the body of a living being transmits radio waves. More precisely, the electrical power distribution network emits radio waves having the same waveform as the electricity it distributes. These waves are picked up by nearby living beings and re-emitted. 
         [0006]    The present invention thus provides a toy including at least one capacitive sensor comprising a metal plate constituting one of the two plates of a capacitor, the second plate being constituted by a portion of a living being in the proximity of the toy, 
         [0007]    at least one effects generator; and 
         [0008]    a control circuit including means for causing effects to take place in response to stimulation of said capacitive sensor; 
         [0009]    the toy being characterized in that said metal plate of said at least one capacitive sensor is used as an antenna for picking up radio frequency transmission from said portion of a living being in the proximity of the toy. 
         [0010]    Advantageously, the radio frequency transmission is at the frequency of an electrical power distribution network. 
         [0011]    In the preferred embodiment, the toy of the invention advantageously comprises: 
         [0012]    means for charging and discharging the capacitor of said at least one capacitive sensor; 
         [0013]    a counter for measuring the discharge time of said at least one capacitive sensor; 
         [0014]    means for starting the counter when the capacitor is charged, and means for stopping the counter when the capacitor is discharged; 
         [0015]    a control circuit connected to the counter and having means for storing a plurality of discharge times issued by the counter, said plurality of discharge times constituting a collection, the control circuit comprising means for analyzing the collection of a plurality of discharge times, and means for detecting variation in the mean value of the collection relative to the mean value of the preceding collection, the control circuit also comprising means for comparing variation in the values of the discharge times within a single collection with a sinusoidal signal of frequency substantially equal to the frequency of an electrical power distribution network; 
         [0016]    a resistor which is located between ground and the base of the first plate of the capacitor of said at least one capacitive sensor, the resistor and the capacitor thus constituting an RC circuit; and 
         [0017]    a variable frequency radio frequency generator generating an electromagnetic field, at least one accessory including a passive resonant circuit constituted by an inductor connected in series with a capacitor and responsive to an electromagnetic field at a determined frequency; and means for determining the presence of at least one accessory and for stimulating the effects generator in such a manner as to cause it to produce an effect. 
         [0018]    In the preferred embodiment, the invention provides a doll having a plurality of capacitive sensors situated at various locations on the doll. 
         [0019]    In another aspect, the invention provides a method of detecting human presence for a toy including a capacitive sensor having a metal plate constituting one of the two plates of a capacitor, the second plate of the capacitor being constituted by a portion of a living being in the proximity of the toy, said method comprising at least the steps consisting in: 
         [0020]    making a collection comprising a plurality of values for the discharge time of the capacitor; 
         [0021]    comparing the mean value of the collection with a reference discharge time value; 
         [0022]    comparing the mean value of the collection with the mean value of the preceding collection; and 
         [0023]    comparing any variations between the discharge time values of the capacitor within the collection with a sinusoidal signal of frequency substantially equal to the frequency of the electrical power distribution network. 
         [0024]    Advantageously, this second aspect of the invention comprises the following characteristics: 
         [0025]    it is concluded that a portion of a living being is present when the variations in the discharge time values present substantially the form of said sinusoidal signal; 
         [0026]    it is concluded that a portion of a living being is present if the mean value of the current collection is substantially equal to the mean value of the preceding collection, and if it was previously concluded that a portion of a living being was present; 
         [0027]    it is concluded that no portion of a living: being is present when the mean value of the current collection is substantially equal to a reference value; 
         [0028]    the reference value is a function of external conditions; and 
         [0029]    the collection comprises ten discharge time values. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Other features and advantages of the present invention appear from the following description of non-limiting embodiments, given with reference to the accompanying drawings, in which: 
           [0031]      FIG. 1  is a diagram showing a doll in accordance with the invention; 
           [0032]      FIG. 2  is a schematic of an electronic circuit associated with a capacitive sensor plate in the  FIG. 1  doll; 
           [0033]      FIG. 3  is a flow chart of the detection method of the invention implemented by the  FIG. 2  circuit; and 
           [0034]      FIG. 4  is a graph plotting variations in discharge time within a collection during a contact. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0035]      FIG. 1  shows the preferred embodiment of the invention. It shows a doll  1  having a plurality of sensors at various locations of its body. These sensors may be of several kinds. Thus, capacitive sensors  2  in accordance with the present invention are situated on the feet, one of the wrists, and one of the cheeks of the doll  1 , while inductive sensors  3  are situated on the lips, the chest, and the other wrist of the doll  1 . Whereas the inductive sensors  3  are used for detecting accessories that are not shown, the capacitive sensors  2  are used for detecting the presence of a portion of a living being in the proximity of the sensor. Other sensors such as gravimetric or radio sensors (not shown) could also be installed on the doll  1 . 
         [0036]    Each capacitive sensor  2  can lead to a different action depending on its location in the body of the doll  1 . By means of this system, malfunction due to the presence of metal objects are avoided. 
         [0037]    The operation of the capacitive sensors  2  is shown in  FIG. 2 . A capacitive sensor  2  is constituted by a detection plate  5  and a resistor  6  connected between the detection plate  5  and ground. On the approach of a portion of a human being  4 , the capacitor  50  formed by the detection plate  5  and the portion of the human being  4  changes so that the discharge time of the RC circuit formed by the resistor  6  and the capacitor  50  is changed. An amplifier  7  serves to recharge the capacitor  50  so that a counter  8  measures the discharge time of the RC circuit. The counter  8  co-operates with the amplifier  7  by means of a start-count signal  81 . Thus, when the capacitor  50  has been charged by the amplifier  7 , the start-count signal  81  informs the counter  8  that it should start counting. Similarly, a stop-count signal  82  serves to stop the counter  8  and to inform a central processor unit (CPU)  9  that it can read the data delivered by the counter  8  on a data bus  84 . The counter  8  and the CPU  9  are synchronized by means of a common clock signal  83 . 
         [0038]    Consequently, in order to start charging the capacitor  50  constituted by the detection plate  5  and the portion of the living being  4 , the CPU  9  instructs the amplifier  7  to start charging by putting the signal  81  in the one state. The amplifier  7  then delivers electrical power to the detection plate  5  until it is charged. When the capacitor  50  constituted by the detection plate  5  and the portion of the living being  4  has finished being charged, the signal  81  changes to zero, thus stopping the amplifier  7  and starting the counter  8 . Once the capacitor  50  constituted by the detection plate  5  and the portion of the living being  4  has been discharged, a Schmidt comparator  10  puts the stop-counting signal  82  to zero, thus stopping the counter  8  and informing the CPU  9  that it should store the discharge-time value present on the bus  84 . 
         [0039]    By repeating this operation a certain number of times, a collection of discharge time values stored in a memory (not shown in the figure) by the CPU  9  is built up, and on the basis of this collection analysis described below makes it possible to determine whether a living being is indeed in the proximity of the doll  1 . This system presents the advantage of being simple and easy to implement. It can then co-operate with the CPU  9  in such a manner as to implement the method shown by the flow chart of  FIG. 3 . 
         [0040]    In addition, the detection plate  5  acts as an antenna for receiving the radio waves transmitted by the nearby portion of a living being. This has the effect of causing the time required for the capacitor  50  to discharge to vary over time, with this variation presenting the form of a sinusoidal signal having the same frequency as the frequency of the electrical power distribution network. 
         [0041]    In  FIG. 3 , a flow chart shows how the detection method in accordance with the invention runs. The method takes place in two distinct stages P 1  and P 2 , P 1  being the sampling stage during which a collection of discharge time values for the capacitor  50  is built up using the circuits shown in  FIG. 2 , and stage P 2  being the analysis stage during which the data collected during the stage P 1  is analyzed. 
         [0042]    The stage P 1  begins with initializing the system (S 100 ). During this step (S 100 ), the value of N is initialized to 10. This value determines the number of discharge times that go to making up a single collection. 
         [0043]    As explained above when describing  FIG. 2 , the capacitor  50  is charged during the next step (S 110 ). Once the capacitor  50  is charged, the counter  8  is started in the next step (S 120 ). The capacitor  50  discharges at this time. The detector  10  serves to detect the end of capacitor discharging in the next step (S 130 ). 
         [0044]    Once the capacitor  50  is fully discharged, the stop-count signal is activated and the CPU stores the value presented by the counter  8  in the next step (S 146 ). A test serves to determine the value of N (S 150 ). If the value of N is not zero, then N is decremented in a step (S 151 ) and another charge cycle is begun: the method returns to step (S 110 ). When the value of N is zero in test step (S 150 ), then the stage P 1  has terminated and a collection of ten values has been built up in the memory of the CPU  9 . 
         [0045]    The stage P 2  serves to analyze the data collected during the stage P 1 . Initially, the mean value of the collection is compared with a reference value. If the mean value is substantially equal to the reference value, then it can be concluded that there is no portion of a living being in the proximity of the detector  5  (S 161 ). Otherwise, if the mean value of the collection is not substantially equal to the reference value, then said current mean value of the collection is compared with the mean value of a preceding collection (S 162 ). If these two mean values are substantially identical and if during the preceding cycle it was concluded that a portion of a living being was in the proximity of the detector of the invention, then it can again be concluded that said portion continues to be in the proximity of the detector. Otherwise, if the mean collection values are not identical, or if it was not decided previously that a portion of a living being was in the proximity of the detector, then the process continues to the next step (S 163 ). 
         [0046]    During step S 163 , variations in the values of discharge time around the mean value of the collection are compared with a sinusoidal signal of frequency substantially equal to the frequency of the electrical power distribution network.  FIG. 4  is a graph showing the discharge times T 1  to T 10  of a single collection. These discharge times T 1  to T 10  vary about a collection mean value Tmean. During step S 163 , the CPU  9  looks for a sinusoidal waveform at a frequency substantially equal to the frequency of the electrical power distribution network in the variations in the values T 1  to T 10  of the discharge time. If, as is the case in  FIG. 4 , it is possible to superpose such a sinusoidal signal on the discharge time values T 1  to T 10 , then it is concluded that a portion of a living being is present in the proximity of the detector. Otherwise, it is concluded that there is interference from a metal object (S 166 ). The method then terminates with a conclusion step (S 170 ) which causes effects to be activated if it has been concluded that a portion of a living being is present in the proximity of the detector. 
         [0047]    In an embodiment, the reference value of step (S 161 ) is readjusted as a function of external conditions such as the temperature, the pressure, or indeed the humidity of the surrounding air.