GB2110143A

GB2110143A - Electrically heated soldering iron

Info

Publication number: GB2110143A
Application number: GB08231574A
Authority: GB
Inventors: Colin P Adamason
Original assignee: LIGHT SOLDERING DEVELOPMENTS L
Current assignee: LIGHT SOLDERING DEVELOPMENTS L
Priority date: 1981-11-09
Filing date: 1982-11-04
Publication date: 1983-06-15
Also published as: GB2110143B

Abstract

An electrically heated soldering iron with a temperature control circuit derives a low voltage for the circuit from a dropper resistance Rd which is tapped from the main heating element Re or, as shown, wound around the main heating element, whereby heat dissipated in the dropper does not warm the handle. The arrangement is primarily for use on mains voltages. <IMAGE>

Description

SPECIFICATION Improvements in electrically heated soldering irons This invention relates to electrically heated soldering irons and more particularly to soldering irons designed to operate from higher voltages, for example 110 or 240 volts, such as mains voltage. With soldering irons of this kind which operate directly from the mains, that is without using a separate power supply unit, it is necessary to provide for dropping of the supply voltage in the actual instrument when a lower voltage is required for feeding electronic circuits for control purposes.

It is found that even when power dissipation is kept to a minimum practical value say about 1.6 watts, unacceptable heating of the handle of the instrument still occurs. When the soldering iron is of the low-voltage kind, say 24 volts, the dissipation is much smaller and no problem arises in such a case.

This invention has for an object to seek to provide a construction30f soldering iron primarily for use on mains voltages wherein the aforesaid drawback is overcome.

According to this invention there is provided an electrically heated soldering iron including a voltage dropping resistance for the supply of a low voltage control circuit, wherein the dropping resistance is incorporated into the electrical resistance heating element structure of the iron.

The dropper resistance may be a seperate resistance element wound around the main heating element or it may comprise a tapping on the heating element. The dropper resistance is therefore in the nature of a extra resistance winding on the structure of the heating winding. The advantages of this arrangement are that the dissipated heat from the dropper resistance is no longer a problem in so far as heating of the handle is concerned and the heat is usefully used in the element. Reduction of the dissipation in the dropper is therefore not so much of a concern.

The invention is further described and illustrated in conjunction with the accompanying drawings, wherein: Figure 1 shows a circuit diagram of the heating element and dropperfor a soldering iron, Figure 2 shows a schematic perspective view of the element structure, and Figure 3 shows a longitudinal section through a typical element structure.

Referring to the drawings Figure 1 shows the electrical circuit wherein Re is the heating element connected across the mains supply points S,C, and Rd is the dropper resistance for supply fo a low voltage between points S,LV. The dropper Rd is located in the heating element structure S and conveniently lies around the element Re as shown in Figure 2. The structure S of the body of the instrument is conventional and typically includes a thermistor in the bit mount to effect control of the temperature. The electrical connections for the resistance Rd and element Re and brought out to a terminal block T, which will be contained in the housing forming the handle. Conventional and known parts of the soldering iron structure are not shown in the drawings.

In Figure 3 the structure is shown in more detail and this comprises the bit mount B which extends up from the handle (not shown) and around the upper end of which is secured the heating element Re wound on a copper body M. The dropper Rd is wound around element Re and the appropriate connection wires are brought out to the terminal block T. The temperature sensing thermistor is located in the bit mount body which is hollow and the leads pass therethrough to connect with a small printed circuit board containing the control circuit which is positioned adjacent the terminal and attached to the terminal pins. This assembly being normally mounted in the housing.

Other configurations are possible within the scope of the invention the essential feature being the dissipation of heat from the dropper to the bit itself and away from the handle.

1. An electrically heated soldering iron including a voltage dropping resistance for the supply of a low voltage control circuit, wherein the dropping resistance is incorporated into the electrical resistance heating element structure of the iron.

2. An electrically heated soldering iron as claimed in Claim 1, wherein the dropper resistance is a seperate resistance wire wound around the main heating element structure.

3. An electrically heated soldering iron as claimed in Claim 1, wherein the dropper resistance is formed by a tapping on the main heating element.

4. An electrically heated soldering iron as claimed in Claim 1 or 2 or 3, wherein the handle of the iron incorporates the control circuit operatively associated with a temperatu#re sensor in the bit mount, the control circuit being secured adjacent a terminal blockforthe heating element and dropper connections.

5. An electrically heated soldering iron as herein described and illustrated in the drawings.

The drawings originally filed were informal and the print here reproduced is taken from a later filed formal copy.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in electrically heated soldering irons This invention relates to electrically heated soldering irons and more particularly to soldering irons designed to operate from higher voltages, for example 110 or 240 volts, such as mains voltage. With soldering irons of this kind which operate directly from the mains, that is without using a separate power supply unit, it is necessary to provide for dropping of the supply voltage in the actual instrument when a lower voltage is required for feeding electronic circuits for control purposes. It is found that even when power dissipation is kept to a minimum practical value say about 1.6 watts, unacceptable heating of the handle of the instrument still occurs. When the soldering iron is of the low-voltage kind, say 24 volts, the dissipation is much smaller and no problem arises in such a case. This invention has for an object to seek to provide a construction30f soldering iron primarily for use on mains voltages wherein the aforesaid drawback is overcome. According to this invention there is provided an electrically heated soldering iron including a voltage dropping resistance for the supply of a low voltage control circuit, wherein the dropping resistance is incorporated into the electrical resistance heating element structure of the iron. The dropper resistance may be a seperate resistance element wound around the main heating element or it may comprise a tapping on the heating element. The dropper resistance is therefore in the nature of a extra resistance winding on the structure of the heating winding. The advantages of this arrangement are that the dissipated heat from the dropper resistance is no longer a problem in so far as heating of the handle is concerned and the heat is usefully used in the element. Reduction of the dissipation in the dropper is therefore not so much of a concern. The invention is further described and illustrated in conjunction with the accompanying drawings, wherein: Figure 1 shows a circuit diagram of the heating element and dropperfor a soldering iron, Figure 2 shows a schematic perspective view of the element structure, and Figure 3 shows a longitudinal section through a typical element structure. Referring to the drawings Figure 1 shows the electrical circuit wherein Re is the heating element connected across the mains supply points S,C, and Rd is the dropper resistance for supply fo a low voltage between points S,LV. The dropper Rd is located in the heating element structure S and conveniently lies around the element Re as shown in Figure 2. The structure S of the body of the instrument is conventional and typically includes a thermistor in the bit mount to effect control of the temperature. The electrical connections for the resistance Rd and element Re and brought out to a terminal block T, which will be contained in the housing forming the handle. Conventional and known parts of the soldering iron structure are not shown in the drawings. In Figure 3 the structure is shown in more detail and this comprises the bit mount B which extends up from the handle (not shown) and around the upper end of which is secured the heating element Re wound on a copper body M. The dropper Rd is wound around element Re and the appropriate connection wires are brought out to the terminal block T. The temperature sensing thermistor is located in the bit mount body which is hollow and the leads pass therethrough to connect with a small printed circuit board containing the control circuit which is positioned adjacent the terminal and attached to the terminal pins. This assembly being normally mounted in the housing. Other configurations are possible within the scope of the invention the essential feature being the dissipation of heat from the dropper to the bit itself and away from the handle. CLAIMS