Abstract:
A control device according one embodiment of the invention includes a detection section detecting a physical state of an object to be detected, a measurement section measuring a physical quantity of an object to be measured, a first control section controlling the measurement section to measure the physical quantity periodically, and a second control section controlling the detection section to detect the physical state of the object to be detected before the first control section starts operating. The first control section outputs a measurement result of the measurement section according to a detection result of the detection section.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a monitoring apparatus, more particularly monitoring apparatus which processes a state detection result of a monitored object according to a motion detection result.  
         [0003]     2. Description of Related Art  
         [0004]     Recently, safety regulations are enhanced in both Japan and the United States. Transportation Recall Enhancement, Accountability and Documentation (TREAD) Act enforced in North America establishes a new standard that requires the installation of a tire pressure monitoring system (TPMS) The standard applies to new vehicles marketed after 2006.  
         [0005]     There are currently two types of TPMS: indirect measurement systems and direct measurement systems.  
         [0006]     The indirect measurement systems monitor the tire pressure by detecting a decrease in air pressure from a difference in the rotational speed of the left and right wheels with a wheel speed sensor used in Anti Lock Brake System (ABS). The systems require substantially no additional cost as long as ABS is installed. However, the systems have drawbacks that air pressure measurement accuracy is lower than direct measurement systems, air pressure is not detectable if air pressure decrease happens in all four tires, and a measurement error occurs when a tire size is changed, and so on. Therefore, not a few consumers&#39; groups in the U.S. are anxious about monitoring with the indirect measurement systems.  
         [0007]     On the other hand, the direct measurement systems measure an air pressure and temperature with a sensor placed in each tire. This system installs a sensor unit in a valve of a tire and monitors all four tires individually. This system therefore has a high monitoring accuracy and allows monitoring of the tire pressure even during parking or stopping. Being more accurate than the indirect systems, the direct systems are expected to prevail over time.  
         [0008]     One of the direct measurement systems is a system that measures the tire pressure at regular time intervals, wirelessly transmits the information to a vehicle, and displays the information for a driver. This system is composed of a transmitter module installed in a tire wheel and a receiver module installed in a vehicle body. The transmitter module includes a plurality of kinds of sensors for detecting pressure, temperature, and so on. The sensors and so on are semiconductor devices and require power supply. A battery is generally used batteries is therefore difficult and thus performed when replacing or discarding a tire. For this reason, improvement in battery life is demanded in tire pressure monitor control systems and monitoring methods.  
         [0009]     In order to increase battery life of a transmitter module installed in a tire, Japanese Unexamined Patent Publication No. 2003-237327 discloses a transmitter module which operates intermittently to reduce an operation time for lower power consumption.  
         [0010]     Since conventional tire pressure monitor control devices cannot replace batteries easily, improvement in battery life and reduction in power consumption are critical.  
       SUMMARY OF THE INVENTION  
       [0011]     According to one aspect of the present invention, there is provided a monitoring apparatus for monitoring a monitored object comprising a motion sensor detecting motion of an object, a sensor detecting state of an object, and a controlling circuit with intermittent operation, performing an operation for a detection result of the sensor during a normal operation duration, the operation determined based on a detection result of the motion sensor detected before the normal operation duration.  
         [0012]     According to another aspect of the present invention, there is provided a monitoring apparatus comprising, a motion sensor detecting motion of a vehicle, a sensor detecting state of a tier of the vehicle, and a controlling circuit repeating a normal operation duration and a power save duration alternately, in a normal operation duration, performing an operation for a detection result of the sensor based on a detection result of the motion sensor detected before the normal operation duration.  
         [0013]     According to another aspect of the present invention, there is provided a method for handling a detected result of the monitored object in a monitoring apparatus comprising detecting motion of an object, detecting state of an object, storing a detection result of the motion, activating a controlling circuit in a power save mode for an operation of a detection result of the state, the controlling circuit changing the operation for the detection result of the state based on the detection result of the motion stored before the activation, and turning the controlling circuit into the power save mode after the operation.  
         [0014]     The controlling circuit determines the operation for the state detection result based on the motion detection result detected before the normal operation duration, resulting in the reduced operation time of the controlling circuit in the normal operation duration.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above and other objects, advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:  
         [0016]      FIG. 1  is a diagram showing the configuration of a tire pressure monitor control device according to the present invention;  
         [0017]      FIG. 2  is a detailed block diagram of a latch;  
         [0018]      FIG. 3  is a view showing input and output signals of a latch; and  
         [0019]      FIG. 4  is a time chart describing the operation of a tire pressure monitor control device according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     A preferred embodiment of the present invention is described hereinafter with reference to the drawings.  FIG. 1  is a diagram showing the configuration of the tire pressure monitor control device according to the present invention. Referring to  FIG. 1 , a tire pressure monitor control device  1000  comprises a micro computer chip  100  (referred to as computer  100  hereafter), a motion sensor  200 , a pressure sensor  300 , and an RF transmitter  400 . The tire pressure monitor control device  1000  is fixed to a vehicle tire and transmits tire pressure data to a receiver which is placed in a dashboard of a vehicle, not shown, for example. The computer  100  is formed of a semiconductor chip.  
         [0021]     The motion sensor  200  detects a physical state of a vehicle as either in drive state or stop state. The motion sensor  200 , for example, includes two electrodes  200   b  at one end inside a thin-walled cylindrical tube  200   a  and a movable terminal  200   d  in the longitudinal direction of the tube  200   a . The terminal  200   d  is fixed a spring  200   c  fixed at the other end of the tube  200   a  and applied force against the motion in the longitudinal direction of the tube  200   a . The spring  200   c  is connected to a ground  200   e . The terminal  200   d  does not touch the two electrodes  200   b  during halts while it touches them with centrifugal force of the rotating vehicle tire (driving state) so that the electrodes  200   b  are connected to the ground  200   e  to provide High level signal to a motion sensor input circuit  104 , which is described later.  
         [0022]     The pressure sensor  300  detects and measures pressure of a vehicle tire. A CPU  101  controls the pressure sensor  300  to measure the tire pressure periodically while controlling the entire computer  100 . The CPU  101  outputs a measurement result of the pressure sensor  300  to the RF transmitter  400  based on a detection result of the motion sensor  200 . Specifically, the CPU  101  outputs the tire pressure data measurement result of the pressure sensor  300  retained in a memory  111 , which is described later, to the RF transmitter  400  when the detection result(s) of the motion sensor  200  retained in a latch  107 , which is also described later, indicates the vehicle (tire) is moving, namely drive state. On the other hand, when the detection result(s) of the motion sensor  200  retained in the latch  107  indicates the vehicle (tire) is stationary, namely stop state, the CPU  101  does not output the tire pressure data measurement result of the pressure sensor  300  retained in the memory  111  to the RF transmitter  400 .  
         [0023]     The CPU  101  has a plurality of operation modes, one is a normal operation mode and another is a power save mode for reduction in the power consumption. The CPU  101  may have more different power save modes. The CPU  101  repeats the normal operation duration and the power save duration, and performs operation for the measurement result during the normal operation duration.  
         [0024]     A latch controller  102  controls the operation of the latch  107  to take in and temporarily hold the detection result(s) of the motion sensor  200  at predetermined timings so that the data retained in the latch  107  indicate the physical state of the vehicle as either drive or stop state, for example. Specifically, the latch  107  takes in the measurement result(s) predetermined time before the CPU  101  starts operating in the normal operation mode. The latch  107  is composed of a plurality of flip-flops, for example.  
         [0025]     A pull-up resistor controller  103  outputs a pull-up control signal periodically to the motion sensor input circuit  104 . A timer for intermittent operation  105  includes the latch controller  102  and the pull-up resistor controller  103  and controls their operation timings according to a reference pulse of a low-frequency oscillator  106 , as well as the intermittent operation of the CPU  101 .  
         [0026]      FIG. 2  is a detailed block diagram of the latch  107 . Referring to  FIG. 2 , the latch  107  is composed of two flip-flops as a latch A  107   a  and a latch B  107   b , a logical AND  107   c , and an inverter  107   d.    
         [0027]     A latch A control signal  107 A and a latch B control signal  107 B are respectively input to the latch A  107   a  and the latch B  107   b  from the timer for intermittent operation  105  . . . A port output signal  107 C is output from the motion sensor input circuit  104  to the latch A  107   a  and the latch B  107   b . A CPU-SW information reading signal  107 D indicates the start-up of the CPU  101  and it is an enable signal from the CPU  101  to the inverter  107   d  to control the output of the inverter.  
         [0028]     The latch  107  outputs signals as shown in  FIG. 3  according to the latch A control signal  107 A and the latch B control signal  107 B.  FIG. 3  is a view showing input and output signals of the latch. Referring to  FIGS. 2 and 3 , before the CPU  101  starts operating (going into the normal operation duration (mode) from the power save duration (mode)), the latch  107  operates by the control of the latch controller  102 , receiving a pull-up resistor control signal output from the pull-up resistor controller  103 .  
         [0029]     The latch  107  takes in and holds the detection results of the motion sensor  200  two times with shifted input timings of the latch A control signal  107 A and the latch B control signal  107 B by a certain period of time. The latch  107  gets the logical product of outputs of the latch A  107   a  and the latch B  107   b  with the logical AND  107   c . The vehicle drive/stop information for two times is retained in the latch A  107   a  and the latch B. Only when the result show stop state (High) at the both timings, it determines that the vehicle is at rest (High) and outputs a drive/stop determination signal  107 E to the CPU  101 .  
         [0030]     It checks the state more than once with a plurality of latch control signals in order to prevent the misdetection of the vehicle (or tire) motion due to the chattering in which the terminal  200   d  repeatedly touches and non-touches the electrodes  200   b , which often occurs during low-speed driving. When a vehicle drives at a low speed, since the detection result of the motion sensor  200  is unstable, detection is performed a plurality of times so as to determine whether the vehicle is driving or at rest from a plurality of detection results. The latch  107  may further include another latch in addition to the latch A  107   a  and the latch B  107   b . The criteria for determining drive state or stop state may be changed as the circuit configuration is altered.  
         [0031]     Referring back to  FIG. 1 , a differential amplifier  108  amplifies a voltage input by the pressure sensor  300 . An A/D converter  109  converts the voltage amplified in the differential amplifier  108  from analog to digital. A ROM  110  is used for temporarily storing data. The memory  111  as a storage section stores measurement results from the pressure sensor  300 . The CPU  101  operates according to a reference signal from an oscillator  112  and periodically operates intermittently by an output signal  105 A of a timer for intermittent operation from the timer for intermittent operation  105 .  
         [0032]     The RF transmitter  400  has an antenna  400   a  and transmits data to an external receiver through the antenna  400   a . The external receiver is placed in a dashboard of a vehicle body, for example.  
         [0033]     The operation of the tire pressure monitor control device according to the present invention is described hereinafter with reference to the drawings.  
         [0034]      FIG. 4  is a time chart to describe the operation of the tire pressure monitor control device of this invention. The timing chart of  FIG. 4  shows a CPU operation, an output signal of a timer for intermittent operation  105 A, a pull-up resistor control signal  103 A, a port output signal  104 A, a latch A control signal  107 A, a latch B control signal  107 B, a drive/stop signal  200 A, and a drive/stop determination signal  107 E.  
         [0035]     Referring to FIGS.  1  to  4 , the timer for intermittent operation  105  counts and generates a plurality of control signals according to a reference signal from the low-frequency oscillator  106 . The timer for intermittent operation  105  outputs the Tb period output signal  105 A of a timer for intermittent operation to the CPU  101 . The CPU  101  is activated at falling edges of the output signal  105 A of a timer for intermittent operation.  
         [0036]     The timer  105  for intermittent operation outputs a pull-up resistor control signal  103 A to the motion sensor input circuit  104  at the same period Tb as the output signal  105 A of a timer for intermittent operation. Further, the motion sensor input circuit  104  outputs a port output signal  107 C to the latch  107  while the pull-up resistor control signal  103 A is High level.  
         [0037]     Then, the latch A control signal  107 A and the latch B control signal  107 B are sequentially input to the latch  107  according to the control of the latch controller  102 . The latch A  107   a  and the latch B  107   b  take in, at respective different timings, the port output signal  107 C generated from the drive/stop signal  200 A indicating drive or stop state according to the signal from the motion sensor  200  when the latch A control signal  107 A and the latch B control signal  107 B are High, respectively. The drive/stop signal  200 A indicates drive state by Low level and stop state by High level. When each of the latch A control signal  107 A and the latch B control signal  107 B changes from High to Low, the latch A  107   a  and the latch B  107   b  shown in  FIG. 2  fixes and retains, at respective timings, the port output signal  107 C, respectively.  
         [0038]     After that, the output signal  105 A of a timer for intermittent operation changes from High to Low, resulting in the CPU  101  which is activated to the normal operation state (High). The CPU  101  powers the pressure sensor  300  on and outputs a signal for controlling the pressure sensor  300  to measure the tire pressure. In accordance with the instruction from the CPU  101 , the pressure sensor  300  provides the measured value to the differential amplifier  108 . The A/D converter  109  converts the amplified analog signal to digital signal and the memory  111  stores the digital tire pressure data.  
         [0039]     A CPU-SW information reading signal  107 D which is generated when the CPU  101  in the power save mode is activated is input to the inverter  107   d  of the latch  107 . In accordance with the input timing of the CPU-SW information reading signal  107 D, the latch  107  outputs to the CPU  101  a drive/stop determination signal  107 E, which is a result of logical ADD operation of the outputs of latch A  107   a  and latch B  107   b.    
         [0040]     Then, the CPU  101  determines whether the vehicle is driving or stopping from the drive/stop determination signal  107 E and outputs the measurement result of the pressure sensor  300  to the RF transmitter  400  in accordance with the detection result of the motion sensor  200 .  
         [0041]     For example, at T 1  in  FIG. 4 , the drive/stop determination signal  107 E is High and indicating stop state. Thus, the CPU  101  goes into a power save mode (Low) without outputting the measurement result of tire pressure data from the pressure sensor  300  which is stored in the memory  111  to the RF transmitter  400 . As shown in  FIG. 4 , the operation time of the CPU  101  is Ta 1  which is shorter than Ta 2  described later.  
         [0042]     On the other hand, at T 2 , the drive/stop determination signal  107 E is Low and indicating drive state. Thus, the CPU  101  outputs the measurement result of tire pressure data from the pressure sensor  300  which is stored in the memory  111  to the RF transmitter  400 . After transmitting the pressure data to the receiver placed in a dashboard or the like of a vehicle body, not shown, through the RF transmitter  400  and the antenna  400   a , the CPU  101  goes into the power save mode (Low). A driver of the vehicle can thereby check the tire pressure during driving with a screen display or the like. In this case, the operation time of the CPU  101  is longer than Ta 1  as shown in  FIG. 4 .  
         [0043]     After that, the output signal  105 A of a timer for intermittent operation is output and the above process is repeated. The TPMS in North America requires detecting the tire pressure within 10 minutes. It is therefore necessary to configure the operation compatible with this standard by a transmission time interval Tb of the output signal of a timer for intermittent operation or the like.  
         [0044]     Since this configuration makes the motion sensor  200  perform detection before the CPU  101  starts operating, it is not necessary to detect the physical operation in the motion sensor  200  for a long time to prevent chattering or the like while the CPU  101  is operating. This reduces the operation time of the CPU  101  to lower the power consumption of the CPU  101 . It is thereby possible to increase the life of a battery, not shown, used in the tire pressure monitor control device  1000 . Specifically, though it takes about 5*10-3 sec to check chattering if the motion sensor  200  detects the physical operation while the CPU  101  is operating, the present invention allows the detection to be performed in about 1*10-3 sec, which is a time required for detecting the tire pressure only.  
         [0045]     Further, since the detection result of the motion sensor  200  is retained in the latch  107  before the CPU  101  starts operating in this configuration, it is not necessary to detect the physical operation in the motion sensor  200  for a long time for chattering or the like during the operation of the CPU  101 . This reduces the operation time of the CPU  101  to further lower the power consumption of the CPU  101 . In the above embodiment, the CPU  101  determines the operation for the detection results of the pressure sensor  300  using the detection results of the motion sensor  200  during the next previous power save duration of the normal operation duration, allowing more precise determination of the vehicle state.  
         [0046]     It is apparent that the present invention is not limited to the above embodiment that may be modified and changed without departing from the scope and spirit of the invention.