EP0582759A1

EP0582759A1 - Watergun having sensor in water tank

Info

Publication number: EP0582759A1
Application number: EP92308935A
Authority: EP
Inventors: Yiu Cheung Poon
Original assignee: Goldmen Electronic Co Ltd
Current assignee: Goldmen Electronic Co Ltd
Priority date: 1992-08-11
Filing date: 1992-09-30
Publication date: 1994-02-16

Abstract

A toy water gun is provided which comprises a tank (3) to hold a liquid to be fired, a piston (11) to compress air into the tank, a nozzle (7) through which the liquid can be fired, a trigger (8), a power source (10), and a liquid sensor means (4) located in the tank and connected to a control means (5) which, in use, operates to open or close a gate means (6) located in or adjacent to the nozzle.

Description

The present invention relates to guns for discharging a liquid, such as toy water pistols.
It is possible to construct a toy water gun comprising a tank to receive the liquid to be fired, a piston to compress air into the tank via a valve means and a trigger to trigger the release of the liquid from the tank. Such a gun would suffer from the drawback that it could be used to deliver all manner of undesirable liquids such as urine, detergent, acid, dyes etc. At the very least such a gun would be considered unpleasant and in the extreme be regarded as dangerous.
According to a first aspect of the invention there is provided a gun for firing a liquid and comprising a chamber for storing liquid and an outlet through which the liquid is fired, characterised in that there is provided sensor means arranged to be responsive to a property of the stored liquid and disabling means operable to prevent liquid from the gun being fired in dependence upon the property.
According to a second aspect of the present invention there is provided a gun which comprises a chamber to hold a liquid to be fired, a piston to compress air in the chamber, an outlet through which the liquid can be fired, and a trigger, wherein a liquid sensor means is located in the chamber and is connected to a control means operable to open or close a gate means located in or adjacent the outlet.
Preferably, the liquid sensor means is a means to detect an impedance value of the liquid within the tank and arranged so that if the impedance value is not substantially the same as that of water, the control means will prevent opening of the gate which, in its normal position, is closed. In one embodiment the sensor is in the form of a pair of electrodes spaced 3mm apart and if the impedance value of the liquid is outside the range 15µA (50K ohm) to 9µA (200K ohm) then the gate will remain closed and the liquid within the tank cannot be fired from the gun. If the distance between the electrodes is greater or smaller than 3mm then the impedance value range will be selected accordingly.
In another embodiment, pulses in the range 1Hz to 10GHz are supplied to one of two spaced apart electrodes. Pulses transmitted through the liquid to the second electrode are detected and used to determine whether the impedance lies within an acceptable range.
The gate means is preferably located within the barrel and is opened and closed under the influence of the control means. Preferred embodiments of the gate are described in detail later in conjunction with the drawings.
The control means may generally be in the form of a printed circuit board (PCB) located within the housing of the gun so that it cannot be tampered with.
For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure 1 is a cross-section through a gun in accordance with the present invention;
Figure 2a is a section at right angle to that of Figure 1 taken through a gate of the gun of Figure 1;
Figure 2b is an enlarged sectional view of a valve mechanism of the gate of Figure 2a taken at right angles to that of Figure 1;
Figure 3 is a vertical section through the gate of Figure 1 and parallel to the plane of Figure 1; and
Figure 4 is a circuit diagram of the PCB control means.
Figure 5 is a circuit diagram of a PCB control means for controlling a second embodiment of a toy gun according to the present invention;
Figure 6 is a cross-section through a gun according to a third embodiment of the invention;
Figure 7 is a vertical section taken through a gate of the gun of Figure 6 in a first configuration.
Figure 8 is a section at right angles to that of Figure 6, taken through the gate of the gun of Figure 6;
Figure 9 is a vertical section taken through the gate of the gun of Figure 6 in a second configuration;
Figure 10 is a circuit diagram of a PCB control means for controlling the gun of Figures 6 to 9.

As shown in Figure 1 a toy gun, shown generally as 1, comprises a housing 2. Located within the housing 2 is a tank or chamber 3 to hold the liquid to be fired and within the tank 3 is a sensor means 4 comprising a pair of electrodes spaced approximately 3mm apart. The sensor means 4 is connected to a control PCB 5 which controls the opening and closing of a normally-closed gate 6 located within a barrel 7 of the gun 1. The gun 1 also includes a pivotally mounted trigger 8 which, on being squeezed, contacts a brass contact or switch 9 to complete a circuit from a power source (battery) 10 to the control PCB 5. Priming of a piston 11 forces air via a valve 12 into tank 3 before operation of the toy gun 1.
The gate 6 is shown in detail in Figures 2a, 2b and 3 and comprises a motor 13, a gear train 14, 15, 16, 17 and a valve assembly shown generally as 18. Motor 13 drives first gear 14 which meshes with second gear 15 which in turn meshes with third gear 16. Third gear 16 meshes with fourth gear 17 which is pressed against a friction disc 19 by means of a first spring 20. A felt disc 21 is provided between fourth gear 17 and friction disc 19 to reduce the rotational motion of fourth gear 17 against friction disc 19. A shaft 22 is fixedly connected to friction disc 19. An aperture 23 is provided in shaft 22. The shaft 22 can be moved from a first "closed" position to a second "open" position. In the closed position the aperture 23 is not in alignment with the tubular barrel 7 and so liquid present in the tank 3 cannot be fired from the gun 1. In the open position the aperture is turned through 90^o and is in alignment with the barrel enabling the gun to fire. A pin 24 is provided on the upper surface of the friction disc 19 and extends upwards therefrom. Pin 24 is movable within a slot 25 from a first to a second position, thereby to move the shaft 22 from the "open" to the "closed" position. At rest, the pin 24 is at the second position and only moves to the first position when the friction disc 19 is rotated by the fourth gear 17, the pin 24 moving along the slot 25. Pin 24 returns to the second position under the action of a second spring 26 when the fourth gear 17 stops rotating.
In use, the trigger 8 is squeezed closing the switch 9 to complete the circuit from the power source 10 to the control PCB 5. If the sensor means 4 senses that the liquid in tank 3 is water then the control PCB 5 opens the gate 6. If, however, the sensor means 4 senses that the liquid in the tank 3 is not water then the gate 6 remains closed and the liquid cannot be fired from the gun.
Figure 4 shows the circuitry of the PCB control means. The electrodes S1 and S2 of sensor means 4 are connected to the PCB as shown in section 1 of Figure 4.
S1, S2, resistors R5, R6, R7, R8, and operational amplifiers IC1a and IC1b give a comparison impedance (V_IN) with R1, R2,VR1, IC1b governing the lower limit of impedance (V_t ) and R3, R4, VR2, IC1a covering the upper limit of impedance (V_H) as shown in sections 2 and 3 of Figure 4.
The output of amplifiers IC1a, IC1b is at high level if

$V_{L} {< V}_{IN} {< V}_{H}$
The output of amplifier IC1a is at low level if

$V_{L} {< V}_{IN} {> V}_{H}$
The output of amplifier IC1b is at low level if

$V_{L} {> V}_{IN} {> V}_{H} .$

Transistors Q2 and Q3 operate the motor 13 as shown in section 4 of Figure 4. The base of transistor Q2 connects to amplifiers IC1a and IC1b. When the base of transistor Q2 is at a high level, the motor 13 starts. When the base of transistor Q2 is at a low level, the motor 13 stops. Transistor Q1 stabilizes the power source. A brass contact or switch 9, as shown in section 5 of Figure 4, firstly connects power to the circuit of the PCB and then connects power to the motor 13.
In a second embodiment of a toy gun according to the present invention, a further switch SW2 is provided which is opened when the aperture 23 has been aligned with the barrel 7 by the action of the motor 13. This allows the current supplied to the motor to be limited once the gate has been opened, the motor requiring a relatively high current during the opening phase. The switch SW2 can be provided at any suitable location in the gun. For example, the switch may be attached to the "open" end 27 of the slot 25, the switch being opened upon contact with the upper end of the pin 24.
Figure 5 shows the circuitry of a PCB control means suitable for controlling this toy gun. The circuit is similar to that of Figure 4 with additional resistors R15, R16, R19, and with an additional transistor Q4. The motor 13 and capacitor C3 are connected on the ground side of the transistors and the high voltage end of resistor R12 is connected to the power supply. As described above, when switch SW1 is closed, transistor Q2 is turned on. While switch SW2 remains closed transistors Q3 and Q4 are on, the motor being supplied with the high current necessary to rotate the aperture. When the aperture 23 is aligned with the barrel 7, the switch SW2 opens and the motor current is limited by the resistor R19 to a low level sufficient to maintain the aperture in its open position. The gun can therefore be fired continuously over a prolonged period without the motor being damaged or overheating and without unnecessarily depleting the power supply.
Figure 6 shows a further embodiment of the present invention. Features in common with the embodiments described with reference to Figures 1 to 5 are designated with like numerals.
The gun comprises an additional, large, piston 28 which can be used to prime the tank 3 through a valve 29. Water is fed from the tank to the water gate 6 through a tube 30. The gate is shown in detail in Figure 7 and comprises a motor 31, a gear train 32, 33, 34 and valve assembly shown generally as 35. The gear 35 meshes with a toothed portion provided at one end of a lever 36.
Figure 8 is a further cross-sectional view through the gate 6, taken at right angles to the plane of Figure 6, and shows the interconnection between the motor, the gear train and the lever. These components are mounted on a motor bracket 40.
As described above, motor 31 acts through the first 32 and second 33 gears to rotate gear 34. Gear 34 in turn causes the lever 36 to move upwards. The lever then causes an arm member 37, connected at one end to the lever 36, to pivot about a pivot 38 which is fixed relative to the housing 2. A stop member 39 is attached to the arm member offset from the pivot so as to move in an upward and downward direction in response to respective upward and downward movements of the lever 36. When in its fully down position, the stop member acts on the tube 30 leading from the tank 3 to block the supply of pressurised water to outlet 41. The tube may be a flexible tube which is compressed by the force exerted by stop member 39. This situation is maintained during non-operational periods by the action of a spring 42 attached at one end to the housing 2. In use, the trigger 8 is squeezed to complete the circuit between the power source 10 and the control PCB 5. As described above, if the sensor means 4 senses that the liquid in the tank is water, then the control PCB opens the gate as is shown in Figure 9, otherwise the gate remains closed as shown in Figure 7.
The gun comprises a second switch SW2 which acts to reduce the motor current when the gate is open as described above. When the arm 37 is rotated about the pivot 38 sufficient to unblock the tube 30, a hook portion 43 which is integral with the arm acts on a switch SW2 to disconnect the switch, thus allowing the current supply to the motor to be reduced for the period during which the trigger is kept depressed.
Figure 10 shows the circuitry of a PCB board 5 for controlling the above embodiment described with reference to Figures 6 to 9. The portion 45 of the circuit comprising R1-6, C1 and IC1a acts as a pulse generator operating at a frequency of between 1Hz and 1GHz. Pulses are fed to electrode S1 of the sensor 4. The portion 46 comprising R7 - 12, C2 - 5, D1, D2 and IC1b receives the pulses arriving at the second electrode S2 of the sensor, processes and amplifies them and converts them into a DC voltage.
The DC voltage is fed into the circuit portion 47, comprising IC2a and IC2b, which is subsequently connected to a motor drive circuit portion 48. These portions are substantially similar to the circuit shown in Figure 5, which is described above, and act to operate the motor if the DC input voltage is within the required range as defined by the reference voltages on the positive input terminal of IC2a and the negative input terminal of IC2b. Switch SW2 acts to reduce the motor current when the stop member is in the blocking position, current being diverted through R29 (equivalent to R19 in Figure 5).

Claims

A gun for firing a liquid and comprising a chamber (3) for storing liquid and an outlet (7, 30) through which the liquid is fired, characterised in that there is provided sensor means (4) arranged to be responsive to a property of the stored liquid and disabling means (18) operable to prevent liquid from the gun being fired in dependence upon the property.
A gun according to claim 1, wherein the sensor means (4) is arranged to detect an impedance value of liquid in the chamber (3).
A gun according to claim 2, wherein the sensor means (4) comprises two electrodes (S1, S2).
A gun according to claim 3, wherein the electrodes (S1, S2) are spaced about 3mm apart and the gate means (6) are operable to allow the gun to fire only if the impedance value of the liquid is within the range 50K ohm (15µA) to 200K ohm (9µA).
A gun according to claim 3 comprising means for supplying electrical pulses to one of the electrodes (S1), means for detecting (46) the pulses at the second of the electrodes (S2) and processing means (46, 47, 48) arranged to allow the gun to fire in dependence upon a property of the detected pulses.
A gun according to claim 5 wherein the pulses have a frequency in the range 1Hz to 1GHz.
A gun according to claim 5 or 6 wherein the processing means includes means (D2, D1, C5) for converting detected pulses into a DC signal.
A gun according to any one of claims 1 to 7, wherein the disabling means (18) has a control means (5) comprising a printed circuit board located within a housing (2) of the gun.
A gun according to any one of the preceding claims, wherein the disabling means (18) comprises a shaft (22) having an aperture (23) extending radially therethrough, the shaft being rotatable about its axis between a first open position in which the aperture (23) is aligned with the through path of the outlet (7) and a second closed position in which the aperture (23) is out of alignment with the through path of the outlet.
A gun according to any one of the preceding claims wherein the disabling means comprises a rotatable shaft (22) to which is coupled a pin (24) slidably engaged in a guide (25), the guide limiting the rotational movement of the shaft between enabling and disabling positions.
A gun according to claim 10, wherein the pin (24) is normally urged to the disabling position under the action of spring (26).
A gun according to any one of claims 1 to 8 wherein the disabling means comprises a stop member (39) moveable in a direction with a component perpendicular to the throughpath of the outlet (30) between a first closed position in which the throughpath is substantially blocked and a second open position in which the throughpath is substantially unblocked.
A gun according to any one of the preceding claims, wherein the disabling means (18) is coupled to be operated by a motor (13).
A gun according to claim 13, wherein the disabling means (18) is coupled to the motor (13) by a friction coupling (19).
A gun according to claim 14 when appended to claim 10, wherein the pin (24) extends from a disc (19) attached to the shaft, the disc providing the friction coupling.
A gun according to claim 13 when appended to claim 12 wherein the stop member (39) is coupled to the motor (13) by a lever (36) acting on a pivotable arm (37) to which the stop member is connected.
A gun according to claim 16 wherein the stop member (39) is normally urged to the first closed position by a spring 42 acting on the arm (37).
A gun according to any one of claims 13 to 17 comprising means operable to reduce the power supplied to the motor when the disabling means is arranged to allow the gun to fire.
A gun according to claim 18 when appended to claim 16 or 17 wherein the means operable to reduce said power comprises a switch operable by the arm (37).
A gun according to any one of the preceding claims comprising a piston (11) operable to compress air in the chamber.
A gun according to any one of the preceding claims comprising a power source (10) for energising the sensor and the disabling means.
A gun comprising a chamber (3) to hold a liquid to be fired, at least one piston (11, 28) to compress air in the chamber (3), an outlet (7, 30) through which the liquid can be fired, and a trigger (8), wherein a liquid sensor means (4) is located in the chamber (3) and is connected to a control means (5) operable to open or close a gate means (6) located in or adjacent the outlet (7, 30).