GB2207331A

GB2207331A - Fish food dispenser

Info

Publication number: GB2207331A
Application number: GB08714684A
Authority: GB
Inventors: Ka-Duk Lam
Original assignee: Sealand Ind Co Ltd
Current assignee: Sealand Ind Co Ltd
Priority date: 1987-06-23
Filing date: 1987-06-23
Publication date: 1989-02-01
Also published as: GB8714684D0

Abstract

A fish food dispenser comprises a container (12) for fish food, and a metering screw (10) mounted for rotation in a metering chamber (11) and driven by an electric motor (M) via a reduction gear train (23) for dispensing fish food from the container. The fish food may be dispensed daily at a time presettable by means of an electronic control circuit (21), or may be dispensed at any time by means of a manual switch provided in the control circuit. The quantity of fish food to be dispensed is also presettable by means of the control circuit. An alarm indicating food is about to be dispensed may be provided. <IMAGE>

Description

FISH FOOD DISPENSER This invention relates to a fish food dispenser.

Many people keep fish as domestic pets. The trouble is to feed the fish daily at regular hours, or when they are away from their homes for prolonged periods it is necessary to find someone to feed the fish.

The present invention seeks to provide a dispenser for automatically dispensing food to fish in a tank.

According to the present invention there is provided a fish food dispenser comprising a container for fish food, power driven dispensing means for dispensing fish food from the container, and means for energising the dispensing means at a preset time.

Preferably, the dispensing means is a motor driven metering device, such as a motor driven metering screw.

Alternatively, the dispensing means could be a vibratory device.

Advantageously, the period of operation of the dispensing device can be varied to vary the quantity of food dispensed.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of a fish food dispenser embodying the invention; Figure 2 is a sectional front view of the fish food dispenser of Figure 1; Figure 3 is a block diagram representing an electronic control circuit of the fish food dispenser of Figure 1; and Figure 4 is a practical implementation of the control circuit of Figure 3.

Referring firstly to Figures 1 and 2 of the drawings, the fish food dispenser shown therein comprises a metering screw 10 mounted for rotation in a metering chamber 11, a container 12 for fish food, a motor unit 13, and a control panel 14.

The container 12 is mounted on the upper wall of the chamber 11 and the lower end of the container 12 communicates with the upper end of the chamber 11 via an opening 15. The container 12 has a removable lid 16 so that the container 12 can be replenished with fish food and the chamber 11 has a discharge opening 17 in one end wall.

The motor unit 13 is secured to the other end wall of the chamber 11 and comprises a motor unit housing 18 accommodating a fractional horsepower p.m.d.c. motor M, batteries 20, a control circuit 21, and a reduction gear train 23.

The motor M is connected to one end of the metering screw 10 via the reduction gear train 23 and is energised by the batteries 20 in response to the control circuit 21.

The control panel 14 is mounted on the front wall of the housing 18 and comprises a digital clock CK, display, set, and lamp buttons 25, 26 and 27 respectively, manually operable pushbutton switch SW, and fish food quantity control knob 29.

In use, the fish food dispenser may be mounted by any appropriate means above the water level on the top of a fish tank. Alternatively, the dispenser may be placed on a fish tank accessory, such as a pump, mounted on the top of the fish tank.

The block diagram of the control circuit 21 shown in Figure 3 comprises the electronic digital clock CK having an alarm signal output which is fed to a two-stage amplifier circuit comprising amplifiers A1 and A2. Such a clock is well known and typically produces an alarm signal every 24 hours. The output of the amplifier A2 is connected to a timing control circuit TC, a control element CE and an amplifier A3. The output of the amplifier A3 is connected to and provided for energising a buzzer B.

The manually operable switch SW is connected to and provided for controlling the timing control circuit TC.

The outputs of the timing control circuit TC and the control element CE are connected to an amplifier A4. The output of the amplifier Aq is connected to the motor M which drives the reduction gear train 23 and the metering screw 10 of the fish food dispenser when energised.

The buzzer B is energised by the amplifier A3 in the presence of an alarm signal from the clock CK.

Simultaneously, the timing control circuit TC is reset and the control element CE operates to ensure the motor M is in an inoperative state.

The alarm signal is arranged to last for approximately 30 seconds and thereafter the buzzer B stops signalling.

Simultaneousely, the control element CE is disabled and the timing control circuit TC operates for a presettable time' interval to energise the motor M. At the end of the preset time interval, the timing control circuit TC ceases to operate and the motor M stops.

Accordingly, the alarm signal is initiated by the clock CK at a preset time and the buzzer B is energised to alert a user of the dispenser that fish food is about to be dispensed. Subsequently, the motor M operates to drive the metering screw 10 to dispense fish food for a preset time interval. Alternatively, the fish food dispenser can be operated at any time by depressing the pushbutton switch SW.

Referring now to Figure 4 of the drawings, a practical implementation of the control circuit 21 is shown. A first DC voltage source V1 is connected between a positive supply line Vcc and earth E. The electronic digital clock CK is powered by a second DC voltage source V2. One terminal of the clock CK is connected to earth E. The other terminal of the clock CK is connected via a resistor R2 to the base of a NPN transistor G1 and connected via a series circuit of a capacitor C1 and a resistor R1 to earth E.

The collector and emitter of the transistor G1 are respectively connected via a resistor R3 to the supply line Vcc and directly to earth E. The collector of the transistor G1 is also connected to the base of a NPN transistor G2. Similarly, the collector and emitter of the transistor G2 are respectively connected via a resistor R4 to the supply line Vcc and. directly to earth E.

The collector of the transistor G2 is connected respectively via resistors Rg, R6 and R7 to the bases of NPN transistors G3, G4 and G7.

The collector of the transistor G3 is connected to the supply line Vcc. A parallel circuit of a capacitor C2 and the pushbutton switch SW is connected between the supply line Vcc and the emitter of the transistor G3 at a circuit node A. The base of a NPN transistor G5 is connected to the circuit node A via resistors R8 and Rg connected in series, the resistor Rg being a variable resistor and being adjustable by the control knob 29. The base of the transistor G5 is also connected to earth E via the collector-emitter path of the transistor G4.

The emitter of the transistor G5 is connected to earth E, whilst the collector thereof is connected to the base of a PNP transistor G6. The emitter of the transistor G6 is connected to the supply line Vcc, whilst the collector thereof is connected via a capacitor C3 to the circuit node A, and via a parallel circuit of the motor M and a capacitor C4 to earth E.

The base of a PNP transistor G8 is connected to earth E via the collector-emitter path of the transistor G7, and the emitter thereof is connected to the supply line Vcc.

The collector of the transistor G8 is connected to earth E via a parallel circuit of a buzzer B and a capacitor C5.

The alarm signal of the clock CK is in the form of a pulsating DC output signal, which is converted into a continuous DC signal by means of a low-pass filter circuit comprising the capacitor C1 and resistor R1 before being fed to the transistor G1.

The pair of transistors G1 and G2, which are referred to in Figure 3 as amplifiers A1 and A2, provide a two-stage amplification to the alarm signal. The transistor G1 is switched on by the alarm signal; otherwise it remains in a blocking state. With the transistor G1 in a saturated state, the base of the transistor G2 is forced close to earth potential and the transistor G2 results in a blocking state. However with the transistor G1 in a blocking state, the base of the transistor G2 is raised to a potential sufficient to switch on the transistor G2.

Therefore the transistors G1 and G2 are in complementary states.

Similarly, the transistors G3, G4 and G7 are controlled by the transistor G2 such that their states are complementary to that of the transistor G2.

The transistors G7 and G8 constitute the amplifier A3 of Figure 2. With the transistor G7 in a conducting state, the base of the transistor G8 is substantially shorted to earth E and the transistor G8 switches on to energise the buzzer B. When the transistor G7 and hence the transistor G8 returns to a blocking state, the buzzer B ceases to operate.

The capacitor C2 functions, as hereinafter described, as a timing element to determine the time interval during which the motor M operates. The transistor G3 is provided to discharge or reset the capacitor C2 when in a conducting state. The switch SW provides an alternative to the transistor G3 for manual operation of the fish food dispenser.

The transistor G5 controls the switching operation of the transistor G6, which are referred to in Figure 3 as the amplifier A4. With the transistor G5 in a saturated state, the base of the transistor G6 is substantially shorted to earth E and the transistor G6 conducts to energise the motor M. The capacitor C4 stabilises the operation of the motor M. Conversely, when the transistor G6 is in a blocking state with the transistor G5, the operation of the motor M is disabled.

The transistor G5 remains in a blocking state when the transistor G4 is in a conducting state which lowers the potential of the base of the transistor G5 substantially to earth potential. With the transistor G4 in a blocking state, the switching of the transistor G5 is controllable via the circuit path comprising the capacitor C2 and the resistors R8 and Rg by the charging condition of the capacitor C2.

The capacitor C2 can be fully discharged by means of either the transistor G3 or the manually operable switch SW. When the transistor G3 returns to a blocking state at the end of the alarm signal or when the switch SW is released, electric current starts to flow along the circuit path. The base potential of the transistor G5 rises to switch on the transistor G5 and subsequently energise the motor M. Charge begins to accumulate in the capacitor C2. A preset period of time later, which is determined by the time constant of the circuit path, the capacitor C2 will be sufficiently charged to prevent further current flowing along the path. The transistor G5 is thereby switched off resulting in the motor M being de-energised.

With this arrangement, the motor M starts to operate when the transistor G3 returns from a conducting state to a blocking state, i.e. when the alarm signal from the clock CK ends. The motor M runs for a preset time interval which is determined by the time constant of the circuit path comprising the capacitor C2 and the resistors R8 and Rg. Hence the capacitor C2 functions as a timing element whose charging time is presettable by the variable resistor Rg. The capacitor C2 and resistor Rg are selected to give a presettable time range between 1 and 12 seconds.

When the transistor G4, which is referred to in Figure 3 as the control element CE, is in a conducting state, the collector-emitter path thereof ensures the blocking state of the transistor G5. This avoids any premature operation of the motor M.

When the motor M starts to run, it produces virtually no back EMF at its terminals. Hence the motor starting current will be a few times higher than its normal running current. This requires a large base current to maintain the conducting state of the transistor G6, and in turn a large base current to maintain the conducting state of the transistor G5. As the circuit path comprising the capacitor C2 and the resistors R8 and Rg is unable to provide sufficient base current to the transistor G5, the capacitor C3 is provided as a feedback of the motor starting current to the base of the transistor G5 via the resistors R8 and Rg. This prevents the malfunction of the transistors G5 and G6 when the motor M starts to run.

Various modifications will be apparent to those skilled in the art, and it is intended to include all such modifications as fall within the scope of protection defined by the appended claims.

Claims

1. A fish food dispenser comprising a container for fish food, power driven dispensing means for dispensing fish food from the container, and means for energising the dispensing means at a preset time.

2. A fish food dispenser as claimed in claim 1, wherein the power driven dispensing means comprise a motor driven metering device.

3. A fish food dispenser as claimed in claim 2, wherein the motor driven metering device comprises a rotatable metering screw, an electric motor for rotating the metering screw, and a reduction gear train between the motor and the metering screw.

4. A fish food dispenser as claimed in any one of the preceding claims, wherein said energising means include a clock settable to generate a dispensing signal at a preset time.

5. A fish food dispenser as claimed in any one of the preceding claims, wherein said energising means include means for varying the period for which the dispensing means is energised.

6. A fish food dispenser as claimed in any one of the preceding claims, including means for signalling that fish food is about to be dispensed.

7. A fish food dispenser as claimed in any one of claims 1 to 3, having a control circuit comprising a clock for providing an alarm signal at a preset time or times, first means responsive to the alarm signal for giving a warning signal and second means responsive to the alarm signal for energising the dispensing means.

8. A fish food dispenser as claimed in claim 7, wherein said second means energises the dispensing menas after said warning signal has been given.

9. A fish food dispenser as claimed in claim 8, including means for preventing energising of said dispensing means while said warning signal is being given.

10. A fish food dispenser substantially as hereinbefore described with reference to the accompanying drawings.