Wireless transmitting-receiving apparatus for a bicycle

Abstract: A wireless transmitting-receiving apparatus in accordance with the present invention is an apparatus for detecting and displaying travel speed of a bicycle which is mounted on a wheel, including a sensor generating one signal per every rotation of the wheel, a signal receiving apparatus for successively receiving signals generated from the sensor, a pulse signal generator generating at least two pulse signals with a prescribed pulse interval for every generated signal, a wireless transmitter for transmitting continuously the generated pulse signals, a receiver for successively receiving the transmitted pulse signals, a converter for converting the received pulse signals into signals corresponding to the inputted signals based on the prescribed pulse interval, a calculator for calculating the travel speed of the bicycle and a displaying portion for displaying the calculated travel speed.

Description: The present invention relates to a wireless transmitting-receiving apparatus and, more specifically to a wireless transmitting-receiving apparatus suitable for use in a speedometer of a bicycle and the like. Recently, a speedometer is often attached to two-wheeled vehicles and, especially on bicycles so as to show, in a simple manner, the travel speed, the travel distance and the like. In a conventional speedometer, a rotation sensor is attached to a fork, and a body of the speedometer is attached to a handle by means of a bracket and the sensor and the bracket are connected to each other by a cord, as shown in Japanese Patent Laying Open No. 57-149967. Signals generated based on the rotation of the front wheel of the bicycle are inputted to the speedometer through the cord, and the travel speed of the bicycle is calculated to be displayed based on the signals. The cord of such a speedometer as described above is often broken by the vibration during traveling as the cord is arranged along the fork. In addition, the appearance of such cord is not very pleasant. In order to eliminate such disadvantages of the speedometer having such cords, wireless transmission of the rotation signal instead of the use of cords has been proposed. However, it is impossible to use a wide space to mount a power supply on a bicycle. Therefore, in order to employ a wireless speedometer for a bicycle, the signals must be transmitted by a transmission unit of low power consumption and the signals must be received by a highly sensitive receiving unit of low power consumption. In such a structure, the receiving unit becomes sensitive to external noises, as the output of the transmitted signal is low. In addition, erroneous signals are likely to be generated due to mechanical or physical vibration and shock during traveling. For example, the speedometer is adapted to calculate the travel speed of a bicycle, such that the rotary signal is outputted as one pulse signal per one rotation of the wheel of the bicycle, the number of generation of the pulse signals are counted, and the travel speed of the bicycle is calculated based on the counted value. When a vibration or a shock generating signals similar to the pulse signals is applied to the receiving unit or the transmitting unit, the pseudo signals may be counted as the proper pulse signals. As a result, the speed of the bicycle can not be accurately counted or displayed. The foregoing is a problem not only of the speedometer for bicycles, but it is common to all wireless transmitting/receiving apparatuses used under the similar conditions. From US-A-4,158,195 a wireless transmitting-receiving apparatus is known comprising a signal generating means generating pulse signals depending on the rotation of a rotary member. Four pulses are generated for each rotation of the rotating member. These pulses are processed by a receiver using two monostable multi-vibrators to generate two pulses with a predetermined length. These pulses are applied to a AND-gate which produces a signal for a counter. From NL-A-78 01 649 a wireless, namely infrared signal transmission receiver system is known wherein the noise immunity is improved by converting single pulses into two or more pulses of equal or different shapes. These are reconverted to original single pulses. It is an object of the present invention to improve the reliability of a wireless transmitting-receiving apparatus so that no pseudosignals may be counted as proper pulse signals. This object is solved by a wireless transmitting-receiving apparatus with the features of claim 1. Preferred embodiments of the invention are given in the subclaims. The wireless transmitting-receiving apparatus structured as described above transmits a signal by converting the same into a plurality of signals, so that the signal can be received without any influence of other signals, whereby the reliability in the transmitting-receiving operation can be improved. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. Figs. 1A and 1B show specific structures of a receiving apparatus and a transmitting apparatus of the transmitting-receiving apparatus in accordance with one embodiment of the present invention; Fig. 2 is a schematic view of a bicycle having a speedometer incorporating the transmitting-receiving apparatus of Figs. 1A and 1B; Fig. 3 is an enlarged view of the portion "X" of Fig. 2; Fig. 4 is a block diagram showing a structure of the transmitting-receiving apparatus shown in Fig. 2; Fig. 5 is a block diagram showing the structure of the transmitting-receiving apparatus in Fig. 1. Fig. 6 shows voltage waveforms at respective nodes of the structure shown in Figs. 1A and 1B; and Fig. 7 shows a specific structure of a receiving apparatus in the transmitting-receiving apparatus in accordance with another embodiment of the present invention. Fig. 2 shows an appearance of a bicycle having a speedometer incorporating the transmitting-receiving apparatus in accordance with one embodiment of the present invention. Fig. 3 is an enlarged view of the portion "X" of Fig. 2. Fig. 4 is a plan view of the receiving apparatus shown in Fig. 2. Fig. 5 is a block diagram showing the structure of the transmitting-receiving apparatus shown in Fig. 1. The structure will be described with reference to these figures. A signal generating portion 20 and a transmitting portion 22 comprise a transmitting apparatus 28 detachably mounted on a fork 34 for the front wheel of the bicycle 24 and a magnet 26 detachably mounted on a spoke 32 of the front wheel. The magnet 26 is attached at a position spaced apart from the axis 36 by a distance corresponding to the distance between the axis 36 of the front wheel and the transmitting apparatus 28. By this structure, a contact of a lead switch (not shown) incorporated in the transmitting apparatus 28 is closed to generate one signal every time the magnet 26 passes the transmitting apparatus 28. The generated signal is outputted as a wireless signal through the transmitting portion 22 of the transmitting apparatus 28 to be received by a receiving apparatus 30 mounted on a stem 19 of the bicycle 24. The receiving apparatus 30 comprises a receiving portion 8 receiving the transmitted signal, a microcomputer 14 for carrying various arithmetic operations such as calculation of the travel speed, travel distance and so on based on the received signal, and a displaying portion 15 formed of, for example, liquid crystal for displaying the result of arithmetic operation as needed. A switch 38 is provided in the receiving apparatus 30 for switching display of the results of arithmetic operations as needed. Figs. 1A and 1B shows specific structures of various portions shown in Fig. 5. The structure will be described in the following with reference to the figures. A lead switch 1 and a resistance R are connected in series between the ground potential and a power supply potential V cc provided by a battery (not shown) incorporated in the transmitting apparatus. A one shot multivibrator 3 and a one shot multivibrator 4 are connected in series between node (a) which is located between the lead switch 1 and the resistance R, and node (c), and further, the node (a) is directly connected to the multivibrator 4, whereby a double pulse generating portion 2 is formed. The pulse width of the pulses generated by the multivibrator 3 is determined by the resistance R 1 and a capacitance C 1 defining a time constant. Similarly, the pulse width of the pulses generated by the multivibrator 4 is determined by the resistance R 2 and the capacitance C 2 defining a time constant. A signal generating portion 20 is formed in this manner. The transmitting portion 22 comprises an oscillating circuit 5 to which the output of the multivibrator 4 is connected, an amplifier 6 amplifying the signals from the oscillating circuit 5, and a transmitting coil 7 for transmitting the amplified signals. In the receiving portion 8, an amplifier 10 is connected to a receiving coil 9 receiving the transmitted signals, and multivibrators 11 and 12 are connected in series between the amplifier 10 and an AND gate 13. The output from the amplifier 10 is also connected directly to an input of the AND gate 13. The pulse width on the pulses generated from the multivibrator 11 is determined by the resistance R 3 and the capacitance C 3 defining a time constant. The pulse width of the pulses generated from the multivibrator 12 is determined by the resistance R 4 and the capacitance C 4 defining a time constant. The output of the AND gate 13 is connected to a microcomputer 14. The displaying portion 15 is also connected to the microcomputer 14. The operation of the transmitting-receiving apparatus in accordance with one embodiment of the present invention will be described in the following with reference to these figures and to the waveform diagram of Fig. 6. The reference characters (a) to (h) in the diagram of waveforms show the voltage waveforms at respective nodes shown in Figs. 1A and B. When the front wheel of the bicycle is rotated and the magnet 26 passes in front of the lead switch 1 in the transmitting apparatus 28, the contact of the switch 1 is closed, whereby a current is generated between the power supply potential V cc and the ground potential, and a pulse voltage is generated at the node (a) (see the waveform (a)). A first voltage is inputted to the one shot multivibrators 3 and 4. By the voltage input, the one shot multivibrator 3 generates pulses having the pulse width R 1 C 1 , defining the pulse interval between two pulses (hereinafter referred to as double pulses) generated for one pulse voltage (see the waveform) (b)). The one shot multivibrator 4 generates a first pulse P1 having the width R 2 C 2 When the time R 1 C 1 is passed from the generation of the first pulse P1 and the pulse output from the multivibrator 3 falls, the multivibrator 4 generates, in response thereto, a second pulse P2 having the same pulse width as the first P1 (see the waveform (c)). In this manner, the first pulse P1 and the second pulse P2 constitute the double pulse. Every time the double pulse is inputted to the oscillating circuit 5 of the transmitting portion 22, the oscillating circuit 5 outputs an oscillating waveform (see the waveform (d)). It is amplified by the amplifier 6 and controls the current flowing through the transmitting coil 7 to transmit radio wave. The radio wave corresponding to the double pulse based on the rotation signal transmitted in this manner is detected as a voltage change by a receiving coil 9 of the receiving portion 8 shown in Fig. 1B. The detected voltage change is amplified by the amplifier 10 and is outputted as double pulse corresponding to the double pulse in the signal generating portion 20 (see the waveform (e)). The first pulse D1 constituting the double pulse is inputted to the one shot multivibrator 11 and to one input of the AND gate 13. However, since no signal is inputted to the other input portion of the AND gate 13, no signal is outputted from the output portion of the gate. The multivibrator 11 receiving the first pulse D1 generates a pulse having the pulse width W1 determined by the time constant R 3 C 3 (see the waveform (f)). At the fall of this pulse, the multivibrator 12 generates a pulse having the pulse width W2 determined by the time constant R 4 C 4 (see the waveform (g)). The pulse width W1 and W2 are defined such that the second pulse D2 is included in the timing of generating of the pulse having the pulse width W 2 generated from the multivibrator 12. When the timing T 1 of operation of the one shot multivibrator 12 of the receiving portion 8 and the pulse width W2 are set as described above, one pulse is outputted from the AND gate 13 when the second pulse D2 of the transmitted double pulse is received (see the waveform (h)). This pulse is a third pulse treated at a rotation signal corresponding to the aforementioned pulse voltage. Namely, the number of pulse generation in a prescribed period of the pulse voltages indicating the number of rotation of the front wheel of a bicycle is the same as that of the third pulse. Therefore, by inputting the third pulses to a one chip microcomputer 14 used for a conventional speedometer and by counting the number of generation of the third pulses, the travel speed of the bicycle can be calculated. The result of calculation is displayed on the displaying portion 15 as needed, and by accumulating the travel speed, the travel distance can be calculated and displayed in the displaying portion 15. Now, when the multivibrators 11 and 12 of the receiving portion 8 are in operation, the multivibrator 11 is adapted to be not responsive to an input. When the output of the multivibrator 12 is at the "high level" and a noise is generated from the amplifier 10 near the generation timing of the second pulse, a signal may be outputted from the AND gate 13, causing a miscount. Another embodiment of the present invention shown in Fig. 7 is a receiving apparatus preventing such a miscount. This embodiment differs from the first embodiment shown in Fig. 1B in that a flipflop circuit 23 is added in the receiving portion 8. The transmitting apparatus may be the same as that shown in the first embodiment of Fig. 1A. The flipflop circuit 23 has its set input S and a reset input R connected to the output of the one shot multivibrator 11 and to the output of the AND gate 13, respectively. The output Q of the flipflop circuit 23 is connected to the one chip microcomputer 14 of the speedometer. By this structure, the output of the flipflop circuit 23 can be permitted provided that there is an output from the multivibrator 11. Namely, even when the output of the multivibrator 12 is at the "high level" and a plurality of noises near the second pulse are received by the AND gate 13, there is no miscounting. Therefore, highly reliable data of speed detection can be inputted. Although the present invention is applied to a speedometer for a bicycle in the foregoing, the application of this invention is not limited thereto. For example, it can be applied to any apparatuses such as a wireless sphygmometer for exercise indoor and outdoor, or an apparatus for detecting rotation speed of an indoor exercise bicycle and any apparatuses which is wireless, in which signal transmission and reception with low power consumption are required and which is susceptible to external noises. Although double pulses are generated and transmission/reception are carried out based on these pulses in the foregoing, three or more pulses may be used, provided that the pulses are generated with prescribed pulse intervals. In that case, these pulses as a whole define one pulse, so that the reliability can be further improved in the transmitting-receiving apparatus. In the present invention, two or more pulse signals having prescribed pulse intervals are generated based on one input signal, and the pulse signals are transmitted and received, as described above. Therefore, even if other pulse signals happen to be mixed because of noise and the like, such signals are not erroneously counted, whereby the reliability of the transmitting-receiving apparatus can be improved. Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being limited only by the terms of the appended claims.

Claims: A wireless transmitting-receiving apparatus, comprising: first signal generating means for successively generating a plurality of signals; characterized by: second signal generating means (2) comprising two first one shot multivibrators (3,4) for generating at least two pulse signals having a prescribed pulse interval for each of the signals generated by said first signal generating means; wireless transmitting means (22) for transmitting said generated pulse signals in a wireless manner; receiving means (8) for successively receiving said transmitted pulse signals; and converting means comprising two second one shot multivibrators (11,12) and an AND gate (13) for converting said received pulse signals into signals corresponding to the signals generated by said first signal generating means, based on said prescribed pulse signals. A transmitting-receiving apparatus according to claim 1, wherein one of said second one shot multivibrators (11,12) and another of said second one shot multivibrators (11,12) are connected in series, and an input signal of said one of said second one shot multivibrators (11,12) and an output signal of said other of said second one shot multivibrators (11,12) are inputted to said AND gate (13). A transmitting-receiving apparatus according to claim 1, wherein said converting means comprises a flipflop circuit (23). A transmitting-receiving apparatus according to claim 3, wherein one of said second one shot multivibrators (11,12) and another of said second one shot multivibrators (11,12) are connected in series, an input signal of said one of said second one multivibrators (11,12) and an output signal from said another of said second one shot multivibrators (11,12) are inputted to said AND gate (13), and an output signal from said one of said second one shot multivibrators (11,12) and an output signal from said AND gate (13) are inputted to said flipflop circuit (23). A transmitting-receiving apparatus according to one of claims 1 to 4, wherein said first signal generating means is attached on a wheel of a two-wheeled vehicle (24) for generating one signal per every rotation of said wheel; calculating means (14) calculates the travel speed of the two-wheeled vehicle (24) by counting said converted signals; and displaying means (15) displays said calculated travel speed. A transmitting-receiving apparatus according to claim 5, wherein said first signal generating means comprises a magnet (26) attached on a spoke (32) of the two-wheeled vehicle (24) and a lead switch (1) and a resistance (R) attached on a fork (34) of the vehicle (24), said lead switch (1) turned ON every time said magnet (26) passes in front of said lead switch (1) to generate one signal. A transmitting-receiving apparatus according to claim 6, wherein said two-wheeled vehicle (24) is a bicycle, and said first signal generating means is attached to a spoke (32) and a fork (34) of a front wheel.

Inventors: SAKURAI NOBUO, SAKURAI, NOBUO
Applicants: CATEYE CO LTD, CAT EYE CO., LTD.
Application year: 1990
Main classification: G08C17
IPC codes: G08C25, G01P3, H03K3, G08C17, G08C19, H04B1, H04Q9