GB2458650A

GB2458650A - Fish tank heater

Info

Publication number: GB2458650A
Application number: GB0805388A
Authority: GB
Inventors: Chiao-Ming Wang
Original assignee: Meiko Pet Corp
Current assignee: Meiko Pet Corp
Priority date: 2008-03-25
Filing date: 2008-03-25
Publication date: 2009-09-30
Also published as: GB0805388D0

Abstract

A fish tank (aquarium) heater includes an outer tube 1 to hold a circuit board 2, the heating coil 3 and a temperature regulation assembly 4. The circuit board has a control circuit 20 and a thermal switch 22. The control circuit is activated through a TRIAC 21 which has an anode connecting to the heating coil and a gate connecting to the thermal switch. ON/OFF of the TRIAC circuit is controlled by the thermal switch to activate the heating coil, thus reducing the current flowing through the thermal switch.

Description

FISH TANK HEATER

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fish tank heater that does not require a thermal switch of a great voltage (current) and can improve durability, enhance accuracy of temperature control and be fabricated at a lower cost.

2. Description of the Prior Art

Conventional temperature control methods for fish tanks generally can be divided into electronic type and mechanical type. For instance Taiwan patent publication No. 454873 discloses an electronic fish tank heater which can accurately control temperature. But its elements are expensive and the cost is higher, thus is not well accepted on the market. The mechanical fish tank heater is less expensive, thus is widely accepted by consumers and becomes the mainstream on the market. U.S. patent No. 6,504,998 (called cited reference hereinafter) is a typical example of such products (refer to FIG. 1 for its structure). The cited reference mainly includes a metal sheet 91 which is warped and deformed when subject to temperature variation so that it can connect to or be separated from an electric contact 92, thereby to control ON/OFF and heating of a heating colt 93. While its structure is simpler and less expensive, it still has drawbacks when in use, notably: 1. The fish tank heater 9 controls heating by means of warping and deformation of the metal sheet 91 caused by temperature variation to connect or separate the electric contact 92. The temperature sensitive and accuracy of the metal sheet 91 is much lower than the electronic type. As a result water temperature in the fish tank often is too hot or too cold. it leaves a lot to be desired in terms of use and control.

2. The metal sheet 91 is directly connected to the electric contact 92 to be coupled with circuit of the heating coil 93. The heating coil 93 is a load of a higher voltage (current). Hence when the higher voltage (current) presents a sparking or arcing phenomenon often occurs when the metal sheet 91 and the electric contact 92 are connected. This result in a carbonized effect on the electric contact 92, and electric connection could suffer. Moreover, the sparking or arcing phenomenon could easily damage the circuit.

Hence how to improve temperature control accuracy and make the cost lower are hot issues in the industry pending to be resolved.

SUMMARY OF THE INVENTION

Therefore it is an object of the invention to provide a fish tank heater that provides a longer durability and can be fabricated at lower cost. It includes an outer tube to hold a circuit board, a heating coil and a temperature regulation assembly inside. The circuit board has a control circuit which is activated through a TRIAC (TRiode Alternating Current, i.e. two silicon-controlled rectifiers) which serves as an operation switch. The TRIAC has an anode connecting to the heating coil and a gate connecting to a thermal switch. The thermal switch has a first connection blade and a second connection blade spaced from each other. The spaced distance can be adjusted by means of the temperature regulation assembly to do setting of temperature control.

Through the thermal switch, ON/OFF of the TRIAC circuit can be controlled to make the heating coil to generate heat. Such a structure does not need to supply a great voltage (current) to the thermal switch. Thus the durability of the fish tank heater is longer, accuracy of temperature control improves and the cost can be reduced.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. I is a perspective view of a conventional fish tank heater.

FIG. 2 is a perspective view of the invention.

FIG. 3 is an exploded view of the invention.

FIG. 4 is a simplified control circuit diagram of the invention.

FIG. 5 is a sectional view of the temperature control assembly of the invention in an operating condition.

FIG. 6 is a sectional view of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 2, 3 and 4, the fish tank heater according to the invention includes an outer tube 1 to hold a circuit board 2, a heating coil 3 and a temperature regulation assembly 4 inside.

The outer tube 1 has a housing chamber, an opening 11 at one end and a closed other end 12.

The circuit board 2 has a control circuit 20 and a thermal switch 22.

The heating coil 3 is held in the outer tube 1 to supply heat source.

The temperature regulation assembly 4 is coupled on the opening 11 of the outer tube 1 and has a regulation switch 14 at one end.

The invention includes the following features: The control circuit 20 is activated by a TRIAC 21. The TRIAC 21 has an anode connecting to the heating coil 3 and a gate connecting to the thermal switch 22. The thermal switch 22 has a first connection blade 221 and a second connection blade 222 spaced from each other at a selected distance which can be adjusted through the regulation switch 41 to control temperature setting. Through the thermal switch 22; ON/OFF of the TRIAC 21 can be controlled to make the heating coil 3 to generate heat.

By means of the construction set forth above users can set a required temperature through the regulation switch 41 (referring to FIG. 5). Moreover, by turning the regulation switch 41 to push the position of the second connection blade 222 the distance between a second contact B located thereon and a first contact A located on the first connection blade 221 can be adjusted to control the temperature setting. When the control circuit 20 is connected to a power source, if water temperature in the fish tank does not reach the temperature set by the temperature regulation assembly 4, the first contact A and the second contact B are connected (referring to FIG. 6) so that the gate of the TR1AC 21 is activated to set the TRIAC 21 ON in a positive direction to allow the heating coil 3 connected to the anode to generate heat.

On the contrary, if the water temperature of the fish tank has reached the setting temperature, the second connection blade 222 is deformed by receiving heat, thus the first connection blade 221 and the second connection blade 222 bounce away from each other (namely the first contact A and the second contact B are separated). Therefore the gate of the TRIAC 21 is not activated, and the heating coil 3 stops heat generation.

According to the invention, only the control circuit 20 receives a higher voltage (current). The thermal switch 22 receives only a small current (voltage). A radiation fin 23 may also be connected to the junction of the control circuit 20 and the heating coil 3 to disperse heat and reduce the thermal loading of the control circuit 20.

The control circuit 20 further includes an indication light 24 to inform users whether the heater is in a heat generating condition. The indication light 24 is a LED or a light bulb.

As a conclusion, the invention is simply structured and can be fabricated at a lower cost. It requires only a small amount of electric power to control ON/OFF of a greater voltage (current) to prevent the disadvantages of the conventional fish tank heater.

While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.

Claims

SI claim: 1. A fish tank heater, comprising: an outer tube which has a housing chamber, an opening at one end and a closed other end; a circuit board which is located in the outer tube and has a circuit board and a thermal switch; a heating coil held in the outer tube to supply heat source; and a temperature regulation assembly which is coupled with the opening of the outer tube and has a regulation switch at one end thereof; wherein the control circuit is activated through a TRiode Alternating Current (TRIAC) which has an anode connecting to the heating coil and a gate connecting to the thermal switch, the thermal switch controlling ON/OFF of the TRIAC to make the heating coil to generate heat.
2. The fish tank heater of claim 1 further having an indication light.
3. The fish tank heater of claim 1, wherein the control circuit and the heating coil are coupled on a junction which is connected to a radiation fin.