GB2219181A - Bite detectors - Google Patents

Abstract

A fish bite detector comprises a rotatably mounted wheel 10 over which, in use, a fishing line passes a that displacement of the line causes rotation of the wheel, the wheel or an element 20 rotatable therewith forming part of a capacitor the capacitance of which varies as the wheel rotates. A circuit senses variations in the capacitance of the capacitor to indicate when the wheel is drawn into rotation. A transmitter may be activated to transmit a coded signal to a remote receiver, identifying the line which has received a bite. <IMAGE>

Description

BITE DETECTOR This invention relates to a bite detector, that is to say a detector for detecting displacement of a fishing line when a bite is taken by a fish.

Various forms of a fish bite detector have been proposed previously, including those in which sensors are provided to detect rotation of a pulley over which the fishing line passes. One such sensor which has been proposed is an optical sensor but the light emitting diode of this draws current continuously and is liable to drain the battery of the detector. Another such sensor which has been proposed is a magnetic sensor but this lacks the resolution which is obtainable from an optical sensor. A detector disclosed in GB-2 150 402-B uses both an optical sensor and a magnetic sensor, in which the optical sensor is normally switched off but is switched off but is switched on for a time if the magnetic sensor detects rotation of the pulley. However this detector is complicated in view of its need for the two sensors.

In accordance with this invention, there is provided a bite detector which comprises a rotatably mounted wheel over which, in use, a fishing line passes so that displacement of the line causes rotation of the wheel, the wheel or an element rotatable therewith forming part of a capacitor the capacitance of which varies as the wheel rotates, and means for sensing variations in the capacitance of said capacitor or indicating when the wheel is dranw into rotation.

In a preferred arrangement an indicating signal is provided if the capacitance changes substantially in value a plurality of occasions in a period of time. In particular a two-state circuit is arranged to change state each time there is a significant change in capacitance of the detector capacitor and the output of the two-state circuit is connected to a charge pump circuit which actuates a trigger circuit if it accumulates a sufficient charge.

Preferably the detector capacitor is incorporated into an oscillator circuit so as to determine its operating frequency. Changes in operating frequency are determined by periodically switching on the oscillator for a predetermined period each time and responding to the signal level of the oscillator output at the end of each such period. Changes in the signal level between successive responses indicate significant changes in the capacitance value.

Also in accordance with this invention there is provided a bite detector which comprises a rotatably mounted wheel over which, in use, a fishing line passes so that displacement of the line causes rotation of the wheel, a transmitter and means for sensing rotation of the wheel to cause the transmitter to transmit a signal to a remote receiver.

With this arrangement, an angler may supervise several fishing lines and the receiver, situated perhaps up top 15 metres from the individual lines, can indicate which line has received a bite.

Embodiments of this invention will now be described by way of examples only and with reference to the accompanying drawings, in which: FIGURE 1 is a side view of a pulley wheel used in a fish bite detector in accordance with this invention; FIGURE 2 is an elevation of an inner surface of one of two plates between which the pulley wheel of Figure 1 is mounted; FIGURE 3 is an end view of a sensor assembly of the detector, comprising the pulley wheel rotatably mounted between the two plates; FIGURE 4 is a circuit diagram of a circuit in which a capacitor, provided by the assembly of Figure 3, is connected, which circuit detects rotation of the pulley wheel; and FIGURE 5 is a front view, partly in section, of a modified bite detector; and FIGURE 6 is a side view of the detector shown in figure 5.

Referring to Figures 1 to 3 of the drawings, there is shown an assembly which forms a capacitor with variable capacitance. The assembly comprises a pulley wheel 10 which is disposed between two parallel, fixed plates 12, 14, the pulley wheel 10 being fitted with a metal bush 16 and rotatably mounted on an axle 18 which extends through aligned holes in the two plates and through the bush 16. The pulley wheel comprises insulating material but is provided on each side with two diametrically-oposed quadrants 11 which are copper-clad. Each of the plates 12, 14 is also formed of insulating material and has an inner surface copper-clad over four separated quadrants 15.

Two opposite copper-clad quadrants of each plate 12, 14 are connected together and the other quadrants serve for shielding. Each plate thus forms a capacitor with the adjacent side of the pulley wheel and these two capacitors may either be connected in series or, as in the example described, connected in parallel. The combined capacitor thus formed exhibits a varying capacitance depending upon the rotary position of the pulley wheel relative to the fixed plates 12, 14. In use, a fishing line passes over the pulley so that in the event of a fish biting and displacing the fishing line, the pulley wheel is drawn into rotation. The capacitor provided by the assembly of Figures 1 to 3 is connected into the circuit of Figure 4 which responds to changes in the capacitance of the capacitor caused by rotation of the pulley wheel.

Referring to Figure 4, the capacitor C provided by the assembly of Figures 1 to 3 is connected in parallel with a larger fixed capacitor Cl so as to limit the range of capacitance variations which the circuit is subjected to. This circuit is powered from batteries BAT and switched on by a switch SW. The parallel combination of capacitors C and C1 determines the operating frequency of an oscillator OSC formed by one half of a CMOS 556 dual timer device. The other half of the CMOS 556 provides a timer TIM arranged to allow the oscillator OSC to run periodically for a time set by the timer TIM. At the end of each period of oscillation, the output level of the oscillator is latched by a D-type flip-flop FF1.The arrangement is therefore such that the Q-output of the flip-flop FF1 will change each time there is a change in capacitance of the sensor capacitor C.

The output of the flip-flop FF1 is connected to a charge pump CP comprising a series capacitor C2 and series diode D1, with a diode D2 connected from the cathode of diode C1 to the +9v rail, a capacitor C3 and resistor R1 connected in parallel from the anode of diode D1 to the +9V rail and a NAND gate G1 having one input connected to the +9V rail and its other input connected to the anode of diode D1. Gate G1 is one of a four-gate 4093 device and acts as a Schmitt trigger. The output of the gate G1 goes high only if the charge accross capacitor C3 of the charge pump CP reaches a threshold level and this occurs only if a sufficient number of charges in the Q-output of the flip-flop FF1 occur in a period of time. Thus the circuit is immune to transient changes in capacitance, e.g. due to drops of water falling into the assembly of Figures 1 to 3, but responds if a number of changes of capacitance, between successive measurements, occur in a period of time, due to the pulley wheel being drawn into rotation.

The output signal from the gate G1 is the alarm signal, indicating displacement of the fishing line. In the example shown in figure 4, this signal is used to switch on a tone oscillator T-OSC via a gate G2, which tone oscillator is based on a piezo-electric transducer PE and provides an audible alarm. Further, the alarm signal is applied to a delay circuit DELAY formed by the spare half of the 4013 device. This delay circuit holds on an LED for a period of say 10 seconds following the onset of the alarm signal.

The alarm signal may also be used as shown to activate a transmitter e.g. a radio or ultransonic transmitter, which transmits a coded signal identifying the detector concerned. A remote receiver may then respond to such a coded signal received from any of a number of different detectors and provide not only an alarm but also an indication of which of the detectors has sensed a bite. Such a transmission system allows an angler to monitor a number of fishing rods from a central receiver/decoder unit.

Referring to Figures 5 and 6, in a modified bite detector a disc element 20 of insulating material is mounted on a common axle with the wheel 10 and rotates between capacitor plates 12, 14. The element 20 therefore rotates with the wheel 10 and is formed with conductive quadrants on its opposite sides, similar to the wheel of Figure 1. The front of the detector casing includes touch-sensitive switches 22, 24, 26 for switching the detector on and off, for stepping up/down the volume of the audible alarm and for stepping up/down the tone of this. The LED 28 is lit when the alarm signal is given, as described above. The radio aerial 30 may be housed within the detector casing. It will further be noted that the detector is mounted on a stalk 32 by way of a ball joint 34, the stalk 32 being for spiking into the ground at its lower end. Once the detector has been tilted on the ball joint to the required angle, it may be clamped in position by a knob 36.

The variable capacitance detectors which have been described do not apply any appreciable force to the fishing line yet are able to detect line movement in either direction.

Moreover, the battery consumption is very low.

Claims (7)

1) A bite detector which comprises a rotatably mounted wheel over which, in use, a fishing line passes so that displacement of the line causes rotation of the wheel, the wheel or an element rotatable therewith forming part of a capacitor the capacitance of which varies as the wheel rotates, and means for sensing variations in the capacitance of said capacitor for indicating when the wheel is drawn into rotation.

2) A bite detector as claimed in claim 1, in which the sensing means is arranged to detect if the capacitance of the capacitor changes substantially in value a predetermined number of occasions in a period of time.

3) A bite detector as claimed in claim 2, comprising a two-state circuit which changes state each time there is a substantial change in capacitance of the capacitor, and a charge pump circuit connected to the output of the two-state circuit.

4) A bite detector as claimed in claim 2, in which the capacitor is incorporated into an oscillator circuit which is periodically switched on for a predetermined period each time, and means for responding to the signal level of the oscillator output at the end of each said period relative to its level at the end of the preceding said period.

5) A bite detector as claimed in any preceding claim, comprising a transmitter which is caused, when the detector senses that the wheel has been drawn into rotation, to transmit a signal to a remote receiver.

6) A bite detector which comprises a rotatably mounted wheel over which, in use, a fishing line passes so that displacement of the line causes rotation of the wheel, a transmitter and means for sensing rotation of the wheel, to cause the transmitter to transmit a signal to a remote receiver.

7) A bite detector substantially as herein described with reference to Figures 1 to 3 and 4 or Figures 4, 5 and 6 of the accompanying drawings.