1. Technical Field
The present invention relates to a foot switch which transmits a signal for commanding generation of active output to an apparatus main body having a function of generating active output, and relates to an output system including such a foot switch and an apparatus main body.
2. Related Art
One example of such an output system is an ultrasonic surgical system disclosed in Japanese Unexamined Patent Application Publication No. 05-023347. An apparatus main body of this ultrasonic surgical system includes a main unit for generating drive signals (high frequency voltage signals). A handpiece having a probe at a tip thereof and gripped by the operator is electrically connected to the main unit through a cable. The handpiece includes therein an ultrasonic transducer which converts the drive signals into mechanical vibration (ultrasonic band signals). The ultrasonic vibration generated by the ultrasonic transducer is transmitted to the probe while being amplified. A water supply/suction path is provided in the handpiece and the probe. The system is so arranged that when the water supply/suction path is connected to a water supply/suction device, water supply/suction treatment can be effected through an opening formed at an end face of the probe and its vicinity.
More specifically, treatment can be performed by destroying and emulsifying tissues such as of liver parenchyma while performing perfusion through the opening formed in the ultrasonically vibrating probe, and by sucking/removing the debris together with the superfusate through the supply/suction path. An electric knife system may be used together with such an ultrasonic surgical system. Hemostatic treatment or the like can be effected by connecting the electric knife to the handpiece to make a high frequency output through the handpiece of the electric knife.
Since the treatment device including the handpiece or an electric knife is gripped by the operator during surgery, it is appropriate that on/off operation of the treatment device is performed through a foot switch except for a case where a pinpoint operation is particularly required (for example, when hemostatic treatment is performed by the electric knife). That is because, since depressing a switch for a long time with fingers to keep a treatment device in an on-state is a great burden to the operator, employing a foot switch which enables the operator to keep depressing the switch by the operator's weight is desirable from an ergonomical point of view.
It is to be noted that in order to enable selection from among different output types, for example, selection between water supply operation and suction operation, a plurality of pedals are generally disposed in a foot switch. Afoot switch is required to have an excellent user-interface design so that the operator can readily distinguish the plurality of pedals.
A foot switch is typically electrically connected to an apparatus main body through a cable to transmit the operational statuses of the foot switch pedals to the apparatus main body through the cable. When using a plurality of different output systems in surgical operation (e.g., when using an ultrasonic surgical system and an electric knife system), a plurality of foot switches are used. The plurality of foot switches are placed close to the operator's feet, and used while there locations are permutated depending on the progress of the surgical operation. In such a case, however, the cables of the plurality of the foot switches sometimes tangle with each other, which significantly lowers the operator's convenience since appropriate locations of the foot switches cannot be ensured. Particularly, in advanced manipulation in which the operator often keeps moving around the operating table during a surgical operation, since the locations of the foot switches are required to be changed following the operator's movement even in a particular case, the chance of the occurrences of the cable tangling increases that much.
In order to prevent surgical operation from stopping due to such tangling of cables, it is known as described in U.S. Pat. No. 6,074,388, for example, to transfer the operational statuses of the pedals of a foot switch to an apparatus main body by means of radio communication. The foot switch in the surgical system described in the '388 patent incorporates a battery as a power source, and is arranged such that a warning is displayed in a display device at an appropriate time, so as to prevent interruption of a surgical operation by the low output voltage of the battery resulting from electrical discharge of the battery. The foot switch is also provided with an auxiliary battery.
Here, in the case of transferring the operational statuses of a foot switch pedal to an apparatus main body by radio communication, the required transmit power of radio signals depends on the use environment of use of the surgical system. For example, if noise caused by the use of an electric knife, and affecting the radio signals is at a high level, or the foot switch is distant from the apparatus main body, or there is an electromagnetic obstacle, the transmit power of radio signals should be made large. Contrarily, if the noise is at a low level, or the foot switch is close to the apparatus main body, or there is not any electromagnetic obstacle, it is satisfactory possible to transfer the operational statuses of the foot switch pedal to the apparatus main body even if the transmit power of the radio signals is relatively low.
However, in such a surgical system in which the operational status of the foot switch pedal is transferred to the apparatus main body by radio communication, transmit power of radio signals has to be set at a comparatively high level, so that the communication between the foot switch and the apparatus main body can be maintained even when there occurs a change in the use environment of the surgical system. Accordingly, the period during which the foot switch can be used, i.e. the period during which power can be supplied by a battery, is reduced. In the surgical system described in the '388 patent, the period during which the foot switch is usable can be extended by incorporating an auxiliary battery in the foot switch. However, the incorporation of such an auxiliary battery causes the size and weight of the foot switch to increase, and thus a problem of poor portability is also an issue.