1. Field of the Invention
The present invention relates to a measurement apparatus and a sensor apparatus, and particularly, to a measurement apparatus for measuring the cadence at which the pedals of a bicycle are worked and the running speed of the bicycle and displaying them, and to a sensor apparatus used therefor.
2. Description of the Background Art
Conventionally, a measurement apparatus including a cadence sensor and a speed sensor is attached to a bicycle for measuring the cadence at which the pedals of the bicycle are worked and the running speed of the bicycle. A reference (an owner's manual available from CatEye Co., Ltd. (CAT EYE ASTRALE 8 CYCLOCOMPUTER CC-CD200, Owner's Manual), 2002) describes handling of such a measurement apparatus.
In the conventional measurement apparatus described in the reference, as shown in FIG. 7, in order to measure the running speed of a bicycle 102, a wheel magnet 125 is attached at a prescribed position on a spoke 103a of a front wheel 103, and a speed sensor 120 sensing the magnetism of wheel magnet 125 is mounted at a prescribed position on a front fork 104 rotatably supporting front wheel 103.
Further, in order to measure the cadence at which the pedals 106 of bicycle 102 are worked (the number of rotation of the pedals), a cadence magnet 126 is attached at a prescribed position on a gear crank 107, and a cadence sensor 121 sensing the magnetism of cadence magnet 126 is mounted at a prescribed position on a chain stay 108 rotatably supporting each of the axes of gear crank 107 and a rear wheel 105.
Signals sensed by speed sensor 120 and cadence sensor 121 are transmitted for processing to a display portion 122 attached to a handle 109 through cables 123 and 124, and displayed as the speed of the bicycle and the number of rotation of the pedals, respectively.
Cable 123 connecting display portion 122 and speed sensor 120 is arranged along front fork 104, and cable 124 connecting display portion 122 and cadence sensor 121 is arranged along a downtube 110. The conventional measurement apparatus is configured as described above.
On the other hand, the conventional measurement apparatus has the following problem. Speed sensor 120 and cadence sensor 121 are electrically connected to display portion 122 through cables 123 and 124, respectively. Accordingly, making the length of cables 123 and 124 as short as possible so as to avoid their complicated arrangement, naturally speed sensor 120 will be arranged on front wheel 103 side. As for cadence sensor 121, as it is necessary to be arranged in the vicinity of gear crank 107, there is a limit on reducing the length of cable 124.
Accordingly, in the conventional measurement apparatus, speed sensor 120 is arranged on front wheel 103 side away from cadence sensor 121. Thus, speed sensor 120 and cadence sensor 121 must be individually mounted to respective prescribed positions and adjusted, and therefore the measuring apparatus is troublesome to be mounted.