Abstract:
A portable transmitter is provided which transmits an operating instruction in the form of a radio wave to a controlled device which continues to operate while receiving the operating instruction. The portable transmitter includes a push switch and a touch sensor. The portable transmitter works to supply the electric power to the touch sensor for a given period of time in response to depression of the push switch. When the touch sensor senses a user&#39;s touch thereon, and the push switch is depressed, the portable transmitter transmits the operating instruction to the controlled device and continues such transmission as long as the touch sensor senses the touch thereon regardless of the depression of the push switch. In other words, once the operating instruction has been outputted to the controlled device, the user is required only to touch the touch sensor in order to make the controlled device continue the operation.

Description:
CROSS REFERENCE TO RELATED DOCUMENT 
     The present application claims the benefits of Japanese Patent Application No. 2010-64907 filed on Mar. 19, 2010, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates generally to a portable transmitter which transmits operating instructions in the form of a radio wave to a controlled device installed, for example, in an automotive vehicle. 
     2. Background Art 
     Japanese Patent First Publication No. 6-252782 discloses a portable transmitter which transmits start instructions in the form of a radio wave to an engine installed in a two-wheel vehicle such as a motorcycle. The portable transmitter has two pushbutton switches installed in opposed ends of a casing thereof. The pushbutton switches are electrically connected in series with each other. Only when the pushbutton switches are both placed in an on-state simultaneously, the portable transmitter outputs the start instructions in the form of a radio wave to the vehicle to start the engine. This minimizes errors in manual operation of the pushbutton switches. 
     An automotive lift-up seat  200 , as illustrated in  FIG. 7(   a ), and a portable transmitter which transmits operating instructions in the form of a radio wave to the vehicle to swivel or rotate the lift-up seat  200  out of the vehicle and lower it to ground or retract the lift-up seat  200  inside the vehicle are known.  FIG. 7(   b ) illustrates such a type of portable transmitter  100 . 
     The portable transmitter  100  includes a casing  110 , a retracting switch  112   a , and a rotating-and-lowering switch  112   b  which are disposed on the same surface of the casing  110 . The retracting switch  112   a  is used to retract the lift-up seat  200  into the vehicle. The rotating-and-lowering switch  112   b  is used to extend the lift-up seat  200  out from the vehicle. The retracting switch  112   a  and the rotating-and-lowering switch  112   b  are each implemented by a pushbutton switch which is to be turned on manually by a user. When the retracting switch  112   a  or the rotating-and-lowering switch  112   b  is held down, the portable transmitter  100  transmits a radio signal carrying a retracting or a rotating-and-lowering instruction to the vehicle. The lift-up seat  200  is then moved into or out of the vehicle according to a received one of the instructions. When the retracting switch  112   a  or the rotating-and-lowering switch  112   b  is released, the portable transmitter  100  stops transmitting the radio signal. The lift-up seat  200  then stops A certain period of time (e.g., 40 sec.) is required between the start and completion of movement of the lift-up seat  200 . The user needs to hold the retracting switch  112   a  or the rotating-and-lowering switch  112   b  down for that period of time. 
     The operations of the portable transmitter  100  and the lift-up seat  200  will be described below in detail with reference to  FIGS. 8(   a ) to  8 ( c ). 
     When the retracting switch  112   a  is depressed, as indicated by a solid line in  FIG. 8(   a ), by the user at time t 101 , the portable transmitter  100  simultaneously transmits, as indicated by a solid line in  FIG. 8(   b ), a radio signal carrying the retracting instruction to the lift-up seat  200 . At time t 102 , the lift-up seat  200  is responsive to the radio signal and, as indicated by a solid line in  FIG. 8(   c ), starts to retract inside the vehicle. The lift-up seat  200  completes the retraction at time t 105 . The user visually perceives the completion of retraction of the lift-up seat  200  and then releases the retracting switch  112   a  at time t 106 . The portable transmitter  100  stops transmitting the ratio signal to the lift-up seat  200 . In this way, the user keeps the retracting switch  112   a  held down for a period of time from time t 101  to time t 106 . 
     As indicated by broken lines in  FIGS. 8(   a ) to  8 ( c ), when the user stops holding the retracting switch  112   a  down at time t 103 , the portable transmitter  100  almost simultaneously stops transmitting the radio signal of the retracting instruction to the lift-up seat  200 . The lift-up seat  200  then stops retracting inside the vehicle. Afterwards, when the user restarts holding the retracting switch  112   a  down at time t 104 , the portable transmitter  100  restarts transmitting the radio signal of the retracting instruction to the lift-up seat  200 . The lift-up seat  200  then restarts retracting into the vehicle. 
     As apparent from the above, the user has to continue to hold the pushbutton switch (i.e., the retracting switch  112   a  or the rotating-and-lowering switch  112   b  which will also be referred to as tact switch below) down from when the radio signal starts to be transmitted to give the lift-up seat  200  the operating instruction until the completion of the operating instruction. The keeping the tact switch held down is not quite a burden on physically unimpaired persons, but on physically impaired persons that are most of users of the lift-up seat  200 . 
     In order to alleviate the physical burden of manipulating the tack switch on the users, the portable transmitter  100  may be designed to continue to transmit the radio signal upon holding down of the tack switch for a short time (e.g., 1 sec.). This, however, may result in the following risk. If the user drops and loses the portable transmitter  100  after the lift-up seat  200  has started to move in response to the operating instruction from the portable transmitter  100 , it will result in impossibility of stopping the lift-up seat  200  urgently. 
     In order to alleviate the physical burden on the users, the retracting switch  112   a  and the rotating-and-lowering switch  112   b  may alternatively be implemented in place of pushbutton switches by touch switches which are to be touched by the user to operate. The tough switches, however, need be supplied with electric power to operate at all the time, thus resulting in a decrease in operating life of a battery of the portable transmitter  100 . 
     The above problem is thought of as also being encountered in automotive power sliding door systems or power backdoor systems designed to operate for a period of time in which operating instructions, as outputted from the portable transmitter through a radio wave, are received. 
     SUMMARY 
     It is therefore an object of the invention to provide a portable device designed to decrease a physical burden on a user&#39;s operation on a push switch without sacrificing the safety and to minimize the consumption of electric energy in a power source. 
     According to one aspect of an embodiment, there is provided a portable device for use in controlling an operation of a controlled device which operates according to a given operating instruction for a period of time in which the controlled device continues to receive the operating instruction. The portable device comprises: (a) a push switch; (b) a power source; (c) a radio transmitter which transmits the operating instruction in the form of a radio wave to the controlled device; (d) a touch sensor which is placed in a touch-sensitive mode when supplied with electric power from the power source, when touched manually in the touch-sensitive mode, the touch sensor sensing a touch thereon; and (e) a controller which supplies the electric power from the power source to the touch sensor for a given period of time in response to the depression of the push switch. When the touch sensor senses the touch thereon, and the push switch is depressed, the controller instructs the radio transmitter to transmit the operating instruction to the controlled device and continues to make the radio transmitter transmit the operating instruction as long as the touch sensor senses the touch thereon regardless of depression of the push switch. 
     Specifically, when the push switch is depressed, and the touch sensor is touched by, for example, a user of the controlled device, the portable device outputs a radio signal indicative of the given instruction to the controlled device and continues to output such a radio signal for a period of time in which the touch sensor is kept touched even after the user releases the push switch. In other words, once the operating instruction has been outputted to the controlled device, the user is required only to touch the touch sensor in order to make the controlled device continue the operation. This eliminates the need for the user to continue the operation on the push switch until completion of the operation of the controlled device, thus resulting in a decrease in physical burden on the user. 
     In case of emergency where the controlled device should be stopped, the user is required only to stop touching the touch sensor to disable the controlled device, thereby ensuring the safety of the operation of the controlled device quickly. 
     The electric power continues to be supplied to the touch sensor for the given period of time in response to the depression of the push switch. Such a period of time may be set to only the length of time required by the radio transmitter to continue to transmit the operating instruction to the controlled device, thus minimizing the consumption of electric energy in the power source. 
     In the preferred mode of an embodiment, the touch sensor is disposed on an area of the portable device where a person holding the portable device in his or her hand is enabled to get an easy touch on the touch sensor. 
     The touch sensor may be disposed on a surface of the push switch. 
     The portable device may also include a casing having a length, a first surface, and a second surface. The second surface extends perpendicular to the first surface. The push switch is disposed in the first surface. The touch sensor is disposed on the second surface. The location of the touch sensor in a lengthwise direction of the casing is substantially the same as that of the push switch. 
     The casing may alternatively have the second surface opposed to the first surface. The push switch may be disposed in the first surface. The touch sensor may be disposed on the second surface. The location of the touch sensor in a lengthwise direction of the casing may be substantially the same as that of the push switch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood more fully from the detailed description given hereinbelow and from the accompanying drawings of the preferred embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments but are for the purpose of explanation and understanding only. 
       In the drawings: 
         FIG. 1  is a circuit diagram which illustrates a portable transmitter according to an embodiment; 
         FIG. 2(   a ) is a front view which shows the portable transmitter of  FIG. 1 ; 
         FIG. 2(   b ) is a side view of the portable transmitter of  FIG. 1 ; 
         FIG. 2(   c ) is a back view of the portable transmitter of  FIG. 1 ; 
         FIG. 3  is a flowchart of an instruction transmission control program to be executed by a controller of the portable transmitter of  FIG. 1 ; 
         FIGS. 4(   a ),  4 ( b ),  4 ( c ),  4 ( d ), and  4 ( e ) are time charts which demonstrate operations of the portable transmitter of  FIG. 1 ; 
         FIG. 5(   a ) is a front view which shows a modification of the portable transmitter of  FIG. 1 ; 
         FIG. 5(   b ) is a side view of the portable transmitter of  FIG. 5(   a ); 
         FIG. 5(   c ) is a back view of the portable transmitter of  FIG. 5(   a ); 
         FIG. 6(   a ) is a front view which shows a second modification of the portable transmitter of  FIG. 1 ; 
         FIG. 6(   b ) is a side view of the portable transmitter of  FIG. 6(   a ); 
         FIG. 6(   c ) is a back view of the portable transmitter of  FIG. 6(   a ); 
         FIG. 7(   a ) is a partially perspective view which shows a lift-up seat that is a device to be controlled by a portable transmitter; 
         FIG. 7(   b ) is a perspective view which shows a conventional portable transmitter; and 
         FIGS. 8(   a ),  8 ( b ), and  8 ( c ) are time charts which demonstrate operations of the portable transmitter of  FIG. 7(   b ). 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference numbers refer to like parts in several views, particularly to  FIG. 1 , there is shown a portable transmitter  1  according to the embodiment. 
     The portable transmitter  1  is designed as a remote wireless transmitter to output operating instructions in the form of radio waves to the lift-up seat  200 , as discussed in the introductory part of this application with reference to  FIG. 7(   a ). The portable transmitter  1  works to selectively output radio signals carrying a rotating-and-lowering instruction (which will also be referred to as an extending instruction below) to rotate the lift-up seat  200  from inside to outside an automotive vehicle and lower it to ground and a retracting instruction to retract the lift-up seat  200  into the vehicle. 
     The portable transmitter  1  is equipped with a retracting switch  12   a , a rotating-and-lowering switch  12   b , touch sensors  14 , a radio transmitting unit  16 , a controller  18 , and a battery  20  which are disposed inside a casing  10 , as illustrated in  FIGS. 2(   a ) to  2 ( c ). The retracting switch  12   a  and the rotating-and-lowering switch  12   b  will also be generally referred to as tact switches  12  below. 
     The casing  10  is, as clearly illustrated in  FIGS. 2(   a ) to  2 ( c ), of a flat shape having six surfaces. One of these surfaces, as will be referred to as a front surface α below, has the tack switches  12  disposed therein. The surface opposed to the front surface α will be referred to as a back surface β below. The other surfaces will be referred to as side surfaces below. One of the side surfaces which is oriented upward in the drawing will also be referred to as an upper end surface γ below. One of the side surfaces which is oriented downward in the drawing will also be referred to as a lower end surface δ below. The other side surfaces facing the left and right sides of  FIG. 2(   a ) will also be referred to as side surfaces ε 1  and ε 2 , respectively. 
     The tact switches  12  are mounted in the front surface α of the casing  10 . The touch sensors  14  are disposed on surfaces of the tact switches  12 . Specifically, the touch sensors  14  are made up of a touch sensor  14   a  attached to the surface of the retracting switch  12   a  and a tough sensor  14   b  attached to the surface of the rotating-and-lowering switch  12   b . The casing  10  has an inner chamber in which the touch sensors  14 , the radio transmitting unit  16 , and the battery  20  which supplies the electric power to the controller  18  are disposed. The battery  20  is made of, for example, a lithium coin cell.  FIG. 1  illustrates the battery  20  as being installed within the casing  10 . 
     Each of the retracting switch  12   a  and the rotating-and-lowering switch  12   b  is, as can be seen in  FIG. 2(   a ), of a rectangular shape, as viewed from the front surface α of the casing  10 . The retracting switch  12   a  is made of a typical push switch (also called a pushbutton switch or an on-off switch) which instructs the lift-up seat  200  to retract into the vehicle. Similarly, the rotating-and-lowering switch  12   b  is made of a typical push switch which instructs the lift-up seat  200  to rotate and lower to ground. This motion will also be referred to as “extension” below. The retracting switch  12   a  and the rotating-and-lowering switch  12   b  are mounted on an upper half of the front surface α of the casing  10 , but may be located on a lower half or a central area thereof. 
     The tact switches  12  are, as can be seen in  FIG. 1 , disposed between ports (not shown) of the controller  18  and ground. Each of the tact switches  12  is so held by a spring (not shown) as to be, as illustrated in  FIG. 2(   b ), flush with the front surface α of the casing  10 . 
     When pressed manually by the user (i.e., an operator of the lift-up seat  200 ), a movable contact of each of the tact switches  12  is moved into the casing  10  to close fixed contacts thereof, thereby establishing an electrical connection between a corresponding one of the ports of the controller  18  and ground, so that a potential of a logic low (L) level is inputted to the controller  18 . 
     Alternatively, when not pressed by the user, the movable contact of each of the tact switches  12  is urged and kept by the spring away from the fixed contacts, thereby breaking the electrical connection between a corresponding one of the ports of the controller  18  and ground, so that the potential of the logic low (L) level is not inputted to the controller  18 . 
     Each of the touch sensors  14  is implemented by a typical touch-sensitive sensor which operates when touched by the user through, for example, his or her finger. Specifically, the touch sensor  14   a  is, as illustrated in  FIG. 2(   a ), of a rectangular shape and slightly smaller in size than the retracting switch  12   a . Similarly, the touch sensor  14   b  is of a rectangular shape and slightly smaller in size than the rotating-and-lowering switch  12   b . The touch sensors  14  are disposed on the surfaces of the tact switches  12  that are an area of the portable transmitter  1  which provides an easy touch on the touch sensors  14  to the user holding the portable transmitter  1  in his or her hand. 
     The touch sensors  14  are electrically connected to the controller  18  and also connected to the battery  20  through the controller  18 . Each of the touch sensors  14  is kept in a touch sensitive mode (i.e., an active state) while being supplied with electric power from the battery  20  through the controller  18 . When kept in the touch sensitive mode and touched by the user, the touch sensor  14  outputs a signal indicative thereof to the controller  18 . When not supplied with the electric power from the battery  20 , the touch sensors  14  are placed in a touch insensitive mode (i.e., an inactive state). 
     The radio transmitting unit  16  is equipped with a transmit antenna which outputs a low-frequency UHF radio wave and is electrically connected to the battery  20 . The radio transmitting unit  16  is operable to output a radio signal of the retracting or rotating-and-lowering instruction to the lift-up seat  200  while being supplied with the electric power from the battery  20  through the controller  18 , while it is inoperable while not being supplied with the power from the battery  20 . The radio transmitting unit  16  may alternatively be designed to transmit a high-frequency RF radio wave or another type of radio wave. 
     The controller  18  is implemented by a known microcomputer equipped with a CPU and memories. The CPU executes programs stored in the memory to perform several given functions which will be described below. 
     The controller  18  is, as described above, electrically connected to the battery  20  and operates on supply of electric power from the battery  20 . Specifically, when either of the retracting switch  12   a  or the rotating-and-lowering switch  12   b  is turned on to input the logic low level signal to a corresponding one of the ports of the controller  18 , the controller  18  is switched from a sleep mode to an active mode. 
     When placed in the active mode, the controller  18  starts to count using a built-in timer the time elapsed from a reference time that is the moment when the controller  18  is switched to the active mode and also supplies the electric power from the battery  20  to a corresponding one of the touch sensors  14  for a preselected touch-sensitive period of time to place the touch sensor  14  in the touch sensitive mode. When touched by the user, the touch sensor  14  outputs a signal indicative thereof to the controller  18 . When switched from the sleep mode to the active mode, the controller  18  also supplies the electric power from the battery  20  to the radio transmitting unit  16  for the same period of time as the above touch-sensitive period of time to place the radio transmitting unit  16  in the active mode in which the UHF radio signal is transmittable to the lift-up seat  200 . The touch-sensitive period of time is set to, for example, 50 sec. to 60 sec. that is the length of time enough for the lift-up seat  200  to start and complete the retracting or rotating-and-lowering operation. 
     The controller  18  is sensitive to the user&#39;s touch on each of the touch sensors  14  and depression of a corresponding one of the tact switches  12  to output the UHF radio signal indicative of a corresponding one of the retracting instruction and the rotating-and-lowering instruction through the radio transmitting unit  16 . The controller  18  then makes the ratio transmitting unit  16  continue to output such a UHF signal as long as the touch sensor  14  is sensing the user&#39;s touch even after the tact switch  12  is released. 
     Specifically, when the retracting switch  12   a  is depressed while the signal indicating the user&#39;s touch on the touch sensor  14  is being inputted to the controller  18 , the controller  18  instructs the ratio transmitting unit  16  to start to output the UHF signal of the retracting instruction to the lift-up seat  200  and then makes the ratio transmitting unit  16  continue to output such a UHF signal while the signal is being outputted from the touch sensor  14  even when the retracting switch  12   a  has been released. 
     When the rotating-and-lowering switch  12   b  is depressed while the signal indicating the user&#39;s touch on the touch sensor  14  is being inputted to the controller  18 , the controller  18  instructs the ratio transmitting unit  16  to start to output the UHF signal of the rotating-and-lowering instruction to the lift-up seat  200  and then makes the ratio transmitting unit  16  continue to output such a UHF signal while the signal is being outputted from the touch sensor  14  even when the rotating-and-lowering switch  12   b  has been released. 
     When entering the active mode from the sleep mode, the controller  18 , as described above, starts to count the time elapsed from the moment when the active mode is entered through the timer. After a given operation period of time which is longer than the touch-sensitive period of time has elapsed, the controller  18  is placed in the sleep mode again. The operation period of time is set to, for example, 300 sec. which is longer than the touch-sensitive period of time for which the touch sensors  14  is kept in the touch sensitive mode. 
     The transmission of each of the retracting instruction and the rotating-and-lowering instruction from the portable transmitter  1  to the lift-up seat  200  will be described below with reference to  FIG. 3 . 
       FIG. 3  is a flowchart an instruction transmission control program to be executed by the controller  18  of the portable transmitter  1 . This program is initiated immediately after the controller  18  enters the active mode upon the depression of either of the tact switches  12 . 
     After entering the program, the routine proceeds to step  11  wherein it is determined whether the touch sensor  14  is sensing the user&#39;s touch thereon, and a corresponding one of the tact switches  12  (i.e., the retracting switch  12   a  or the rotating-and-lowering switch  12   b ) is depressed or not. 
     If a NO answer is obtained in step  11 , that is, the touch sensor  14  is not sensing the user&#39;s touch or the tact switch  12  is not depressed, it means that the user has depressed the tact switch  12  through the touch sensor  14 , but released his or her finger therefrom immediately or has stopped depressing only the tact switch  12  immediately. The portable transmitter  1 , therefore, does not output the UHF radio signal indicative of one of the retracting instruction and the rotating-and-lowering instruction which corresponds to the one of the tact switches  12  having been depressed. The routine then proceeds to step  12  wherein the sleep mode is entered after elapse of the above operation period of time and terminates. 
     Alternatively, if a YES answer is obtained in step  11 , that is, the touch sensor  14  is sensing the user&#39;s touch, and the tact switch  12  is depressed, it means the user intends to send the operating instruction to the lift-up seat  200  through the portable transmitter  1 . The routine then proceeds to step  13  wherein the portable transmitter  1  starts to output the radio signal of the operating instruction to the lift-up seat  200 . 
     The routine proceeds to step  14  wherein it is determined whether the touch sensor  14  is still kept touched or not. If a NO answer is obtained meaning that the touch sensor  14  is no longer touched, then the routine proceeds to step  12  to place the controller  18  in the sleep mode and stop transmitting the radio signal to the lift-up seat  200 . Alternatively, if a YES answer is obtained meaning that the touch sensor  14  is still kept touched, then the routine proceeds to step  15  wherein it is determined whether the touch-sensitive period of time has elapsed since the portable transmitter  1  entered the active mode or not. If a YES answer is obtained meaning that the touch-sensitive period of time expires, then the routine proceeds to step  12  and terminates. Alternatively, if a NO answer is obtained meaning that the touch-sensitive period of time does not yet expire, the routine proceeds to step  15  wherein the controller  18  makes the ratio transmitting unit  16  to continue to transmit the radio signal to the lift-up seat  200 . 
     After step  16 , the routine returns back to step  14  to determine whether the touch sensor  14  is still kept touched or not. 
     The operations of the portable transmitter  1  and the lift-up seat  200  will be described with reference to  FIGS. 4(   a ) to  4 ( e ). Solid lines demonstrate an example where the user pushes the tact switch  12  at time t 11  and stops pushing it at time t 13  when the user has perceived that the lift-up seat  200  has started to move according to the operating instruction, as requested by the pushed tact switch  12 , but still continues to touch the touch sensor  14 , and where the user has found at time t 14  that the operation of the lift-up seat  200  has been completed and stops touching the tack sensor  14 . 
     When the tact switch  12  is, as illustrated in  FIG. 4(   a ), turned on by the user at time t 11 , the controller  18  of the portable transmitter  1  is switched from the sleep mode to the active mode. The controller  18  simultaneously supplies, as indicated by the solid line in  FIG. 4(   b ), the electric power from the battery  20  to the touch sensor  14 . Upon the supply of electric power, the touch sensor  14  is, as indicated by the solid line in  FIG. 4(   c ), placed in the touch sensitive mode and outputs a signal indicating the user&#39;s touch thereon to the controller  18 . The controller  18  then determines that the user&#39;s touch is sensed by the touch sensor  14 , and the tact switch  12  is depressed and makes, as indicated by the solid line in  FIG. 4(   d ), the radio transmitting unit  16  start to output the UHF ratio signal indicating the operating instruction, as requested by the depressed tact switch  12 . At time t 13 , the lift-up seat  200 , as indicated by the solid line in  FIG. 4(   e ), starts to move according to the instruction received through the UHF ratio signal and completes it at time t 14 . When the user perceives the completion of operation of the lift-up seat  200  and releases his or her finger from the touch sensor  14  at time t 14 , the touch sensor  14 , as indicated by the solid line in  FIG. 4(   c ), stops outputting the signal indicative of the user&#39;s touch to the controller  18 . The controller  18 , as indicate by the solid line in  FIG. 4(   d ), stops the radio transmitting unit  16  from transmitting the UHF signal to the lift-up seat  200  and also stops, as indicate by the solid line in  FIG. 4(   b ), supplying the electric power from the battery  20  to the touch sensor  14 . The controller  18  then enters the sleep mode. 
     Broken lines in  FIGS. 4(   a ) to  4 ( e ) demonstrate an example where the user releases his or her finger from the touch sensor  14  at time t 15  even when the operation of the lift-up seat  200  is not yet completed. When the user stops touching the touch sensor  14  at time t 15 , the touch sensor  14 , as indicate by the broken line in  FIG. 4(   c ), stops outputting the signal indicative of the user&#39;s touch to the controller  18 . The controller  18 , as indicate by the broken line in  FIG. 4(   d ), stops the radio transmitting unit  16  from transmitting the UHF signal to the lift-up seat  200  and also stops, as indicate by the broken line in  FIG. 4(   b ), supplying the electric power from the battery  20  to the touch sensor  14 . The controller  18  then enters the sleep mode. 
     Although not illustrated in  FIGS. 4(   a ) to  4 ( e ), when the user continues to touch the touch sensor  14  after time t 14  when the operation of the lift-up seat  200  is completed, the controller  18  enters the sleep mode after the elapse of the touch-sensitive period of time since the time t 11 . 
     When the user continues to touch the touch sensor  14 , but releases the tact switch  12  or stops touching the touch sensor  14  between time t 11  and time t 12 , the controller  18  enters the sleep mode after the elapse of the above described operation period of time since the time t 11 . 
     As apparent from the above discussion, the portable transmitter  1  starts to output the radio signal indicative of the selected operating instruction to the lift-up seat  200  at the time when the user&#39;s touch on the touch sensor  14  is sensed, and the tact switch  12  is turned on and continues to output it as long as the user&#39;s touch is being sensed regardless of whether the tact switch  12  has been released or not. In other words, the user is required only to continue to touch the touch sensor  14  after the portable transmitter  1  has started to output the operating instruction to the lift-up seat  200  in order to complete the operation of the lift-up seat  200 , thus resulting in a decrease in physical burden on the user. 
     If an emergency arises, the user may stop touching the tact switch  12  to stop the operation of the lift-up seat  200  immediately. This ensures the safety of the user. 
     The portable transmitter  1  is responsive to the turning on of the tact switch  12  to supply the electric power from the battery  20  to a corresponding one of the touch sensors  14  only for the touch-sensitive period of time. The touch-sensitive period of time is set to the length of time required for the lift-up seat  200  to start and complete the retracting or rotating-and-lowering operation, thus minimizing the consumption of electric power of the battery  20 . 
     The touch sensors  14  are, as described above, disposed on the surfaces of the tact switches  12  that are in an area of the portable transmitter  1  where the user can keep his or her finger placed on the touch sensors  14  easily while holding the portable transmitter  1  in his or her hand, thus alleviating the physical burden on the user. 
     While the present invention has been disclosed in terms of the preferred embodiments in order to facilitate better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modifications to the shown embodiments which can be embodied without departing from the principle of the invention as set forth in the appended claims. 
     The touch-sensitive period of time for which each of the touch sensors  14  is placed in the active mode to be sensitive to a touch of the user thereon is, as described above, selected to be the time required by the lift-up seat  200  to start and complete the retracting or rotating-and-lowering operation plus a given marginal time, but may be set to another period of time. For example, the lift-up seat  200  is designed to transmit a radio signal indicating the completion of operation thereof. The portable transmitter  1  is also designed to receive the signal from the lift-up seat  200  to know the completion of operation of the lift-up seat  200 . The controller  18  may variably set the touch-sensitive period of time to a time interval from when the controller  18  is placed in the active mode until the controller  18  receives the signal indicating the completion of operation of the lift-up seat  200 . In other words, the controller  18  may continue to supply the electric power to the touch sensor  14  until the completion of operation of the lift-up seat  200 . 
     The touch sensors  14  are mounted on the surfaces of the tact switches  12  on the front surface α of the casing  10  of the portable transmitter  1 , but may alternatively be, as denoted by  14   c  and  14   d  in  FIGS. 5(   a ) to  5 ( c ), affixed to the side surfaces ε 2  and ε 1 , respectively, which are perpendicular to the front surface α. The casing  10  may be designed to have a given length. The locations of the touch sensors  14   c  and  14   d  in the lengthwise direction of the casing  10  may be substantially the same as those of the tact switches  12  on the front surface α. Only either one of the touch sensors  14   c  and  14   d  may be attached to the portable transmitter  1 . 
     The portable transmitter  1  may be, as illustrated in  FIGS. 6(   a ) to  6 ( c ), designed to have only a touch sensor  14   e  which is operable with both the tact switches  12   a  and  12   b . The touch sensor  14   e  is affixed to the back surface β of the casing  10  of the portable transmitter  1 . The location of the touch sensor  14   e  in the lengthwise direction of the casing  10  may be substantially the same as those of the tact switches  12  on the front surface α. 
     As illustrated in  FIGS. 2(   a ) to  6 ( c ), the touch sensors  14  are preferably located on an area of the portable transmitter  1  where the user holding the portable transmitter  1  in his or her hand makes his or her finger touch the touch sensors  14  naturally. 
     The touch sensors  14  may alternatively be disposed on at least one of the upper end surface γ and the lower end surface δ extending perpendicular to the front surface α of the casing  10 . In other words, the touch sensors  14  may be located on an area of the portable transmitter  1  where the user holding the portable transmitter  1  in his or her hand extends his or her finger to the touch sensors  14  easily. 
     The portable transmitter  1  may be designed to be used with automotive power sliding door systems or power backdoor systems which are operable for a period of time in which operating instructions, as outputted from the portable transmitter  1  through a radio wave, are received.