Hair straightener

Abstract

A hair treatment device comprising a base having means for collection to an electrical power supply, the base including a socket including a first electrical connector, tongs comprising a pair of limbs including at least one resistive of heating element, the limbs being connected by a hinge, the tongs further comprising a socket engaging portion including a second electrical connector, the socket engaging portion being adapted to releasably engage the socket so that the first electrical connector connects to the second electrical connector to connect the resistive element to the power supply, wherein the limbs are arranged to extend upwardly when engaged to the base.

Description

This invention relates to an electric hair straightening or hair curling device, particularly, but not exclusively, a hair straightener.

Conventional hair straighteners comprise a pair of heatable plates having heating elements in hinged limbs permanently attached to a power cable for connection to a mains supply. Such a device has a number of disadvantages. Permanent connection of the power cable can be inconvenient, hampering free use of the straightener.

The limbs of such prior devices are biased outwardly by a spring. This leads to a risk that a user may inadvertently grasp one of the heated limbs when picking up the device. Furthermore, the heated tongs may be laid down on a thermally sensitive surface or combustible material.

According to the present invention a hair treatment device comprises a base having means for connection to an electrical power supply, the base including a socket including a first electrical connector,

• • the straightener body comprising a pair of limbs including at least one resistive of heating element, the limbs being connected by a hinge,
  • the straightener further comprising a socket engaging portion including a second electrical connector, the socket engaging portion being adapted to releasably engage the socket so that the first electrical connector connects to the second electrical connector to connect the resistive element to the power supply, wherein the limbs are arranged to extend upwardly when engaged to the base.

The present invention provides a cordless connection for a hair straightening or curling device and confers several advantages over previously known devices. The heating limbs are prevented from contacting and damaging an underlying surface such as a polished dressing table. Furthermore the upward arrangement of the limbs during heating allows a higher power to be supplied without a risk of damage to an underlying thermally sensitive or combustible surface.

In a preferred embodiment a releasable latch is provided to retain the tongs in the socket.

In preferred embodiments both limbs include resistive elements and have a heated hair engaging surfaces. The width of each heatable surface may be equal to or greater than 2.5 cm. Alternatively a narrower but thicker arrangement may be provided to afford a high thermal mass. In such arrangement a higher thermal mass is provided than with a conventional narrow heating element for a hair curling or straightening device.

In preferred embodiments the opening of the socket extends upwardly from the base.

Resilient means are preferably provided to urge the limbs into an open, spaced apart orientation. The resilient means may comprise one or more springs.

In a particularly preferred embodiment the limbs are partially closed when the tongs are engaged in the socket. The reduced separation between the tongs in the partially closed position may be selected to make it difficult for a user to accidentally insert a finger between the heated limbs while the tongs are engaged in the socket. This is particularly beneficial with a relatively high powered device.

Partial or complete closing of the limbs when engaged in the socket confers the additional advantage that heat loss from the heating elements is reduced because radiant heat from one element impinges on the other adjacent element. In preferred embodiments the two elements do not touch during the heating process to avoid a risk of over heating.

Use of heating elements with a width of 2.5 cm or more has the advantage that a greater surface area is available to allow hair to be straightened more quickly. Further the larger thermal mass means that the device can be used for longer periods without re-heating. However heating of a higher thermal mass may be slower. In preferred devices in accordance with the present invention a higher power capacity is provided. This is possible as the limbs are safely stowed in a upright position during heating.

The heating element may comprise an aluminium core coated with a ceramic material. A ceramic resistive heating element may be provided within the core. This heating arrangement has a higher thermal mass than alternative arrangements, allowing heat to be retained and also permitting use of high power resistive elements. Furthermore, ceramic coated aluminium elements are cheaper and easier to manufacture than solid ceramic elements. However, solid ceramic elements may he used if desired.

Aluminium cored heating plates having ceramic elements are beneficial because the heating time is quicker facilitating use in a cordless unit.

In the preferred embodiments of the invention the heating elements reach a temperature of 180-220° C. when the plates are in the open position. This temperature may be achieved within 1 minute. When removed from the base the heating plates may maintain a temperature above 140° C. for at least 4 minutes and re-heat from 140-200° C. within 20 seconds or less when engaged from the base.

Use of a separate base allows provision of a digital display and convenient actuation controls. This avoids the need for provision of controls in the electrical connector lead. Furthermore the digital display in the base can be readily observed irrespective of the orientation or location of the tongs.

In an alternative embodiment a display may be provided in the straightener. Use of wider plates than in conventional devices allows the read out to be located at an upper portion of the tongs if required, facilitating legibility of the display. In previous devices a display has been provided in the handle or making it difficult to observe the display during use.

In preferred embodiments the socket securely engages the straightener to that a secure electrical connection is provided. The socket may be axially elongate, extending upwardly to provide a generally cylindrical socket to receive the tongs.

The latch may be integral with one limb of the straightener so that the latch may be released by urging the plates together against the action of the spring. This avoids the need for a separate moving part. In a preferred embodiment the latch includes a tooth or otherwise shaped formation which engages an annular recess on the exterior of the cylindrical socket.

In the preferred embodiments the case may incorporate a rotatable spool for storage of the power supply cable.

The invention is further described by means of example but not in a limitative sense with reference to the accompanying drawings of which

FIG. 1 is a perspective view of a hair straightener in accordance with this invention,

FIGS. 2 and 3 shows the base of a straightener in accordance with the invention,

FIGS. 4 to 6 contain several views of the straightener body.

The hair straightener shown in FIG. 1 comprises a base (1) having a mains power cord (not shown) extending to a plug (not shown), The cord extends from the rear of the base. A switch (3) and LED displays (4) are mounted on the front of the base to permit the device to be switched off or between on and standby positions and to indicate the status of the device.

A cylindrical socket (5) extends axially upwardly from the centre of the generally cylindrical base (1) and provides a recess (13) into which a corresponding shaped lower portion (6) of the straightener body or tongs (7) may be received and engaged to an electrical connection (4) between the straightener (7) and power supply to a latch (8) integral with one limb of the straightener (14) engages a formation (15) in the outer surface of the socket (5) to retain the tongs when engaged within the socket. The latch (8) may comprise an arm having an inwardly facing tooth (16) or otherwise shaped projection to engage within an annular recess in the exterior of the cylindrical sleeve (5).

The straightener body includes two plates (9),(10) joined for pivoted movement at a lower hinge (11) and biased outwardly by means of a spring (not shown). When the straightener body is removed from the base the plates are urged apart by the spring to allow a users hair to be inserted between them.

In a preferred embodiment the limbs must be partially or completely closed to allow the lower portion (6) to be received within the socket (5).

Each plate (9),(10) includes a heating element electronically connected to the base (6) of the body for connection to the power supply. Each element comprises a generally rectangular ceramic element having a lateral width of 2.5 cm or more. Each element comprises an aluminium core coated with a ceramic material and having a ceramic resistive element within the aluminium core. Each element has a power consumption of 40-80 W more preferably about 80 W in the steady state rising to a peak of 400-500 W when the element is heating from cold when first turned on.

In use of the hair straightener the heated plates are manually pressed together, the base inserted into the socket and the plates released so that the latch (8) engages the outer surface of the cylindrical sleeve (5). The power may then be turned on to heat the elements (11),(12) an LED display shows when the elements have reached the temperature. The handle of the straightener may then be grasped urging the limbs together to release the latch (8). Relaxation of the hand grip allows the straightener to open for hair to be inserted. The tongs can then be closed grasping the hair until the temperature of the elements drops below the working temperature. The straightener is then reinserted into the base to allow them to reheat.

Claims

1. A hair treatment device comprising:

a base having means for connection to an electrical power supply, the base including a socket, the socket including a first electrical connector; and

a straightener comprising:

a pair of limbs including at least one resistive of heating element, the limbs being connected by a hinge; and

a socket engaging portion including a second electrical connector, the socket engaging portion being adapted to releasably engage the socket so that the first electrical connector connects to the second electrical connector to connect the resistive element to the power supply, wherein the limbs are arranged to extend upwardly when engaged to the base.

2. A device as claimed in claim 1, including a releasable latch to retain the straightener in the socket.

3. A device as claimed in claim 1, comprising two limbs each including a resistive element having heatable hair engaging surfaces.

4. A device as claimed in claim 3, wherein the width of the heatable surface is equal to or greater than 2.5 cm.

5. A device as claimed in claim 1, wherein the opening of the socket extends upwardly from the base.

6. A device a as claimed in claim 1, including resilient means arranged to urge the limbs into an open spaced apart orientation.

7. A device as claimed in claim 1, wherein the limbs are partially closed when the straightener are engaged in the socket.

8. A device as claimed in claim 1, wherein the heated plates comprise an aluminium core coated with a ceramic material.

9. A device as claimed in claim L wherein the socket is axially elongate extending upwardly to provide a generally cylindrical socket to receive the straightener.

10. A device as claimed in claim 1, wherein the latch is integral with one limb of the straightener.