The present invention relates to personal appliances according to the preamble of claim 1 and is concerned with an improved personal appliance comprising a sensor.

In the different fields of personal appliances, efforts are taken to make the appliance efficient and user-friendly. Some appliances comprise sensors.

Published German patent application DE 31 12 384 A1 (filed by Müholos-Werk Alfred Müller) discloses a hood dryer. Conventional hood dryers are described as typically allowing for the selection of a heating temperature and a speed of the fan. Both values can often be selected continuously. However, according to this disclosure, it takes a lot of experience, even for a hair dresser, to make the right selections. Therefore, it can happen that the hair is still wet when the hood dryer is switched off according to the selection made when starting the drying process. The disclosed invention attempts to avoid this by providing a wetness sensor. This wetness sensor is supposed to end the process when the hair is sufficiently dry. Air circulating within the hood dryer is guided to the wetness sensor and the sensor is connected to an electrical circuit which can end the drying process by switching off the ventilation fan and the heater.

A dryer hood is a relatively spacious personal appliance. Hence, it is relatively easy to place one or several sensors in a dryer hood. As a dryer hood is a very specific type of a personal appliance comprising the hood as a closed space, it is relatively easy to find an appropriate place for a sensor and to make representative measurements.

US patent 4,602,143 (to Clairol Incorporated) discloses an infrared hair styling device. This device is provided in the form of a curling iron with an infrared radiation source. The curling iron comprises a hollow barrel for radiating infrared radiation. The barrrel is substantially transparent to radiation. The curling iron is also provided with a circuit for energizing the infrared source in a cyclical manner in order to maintain the temperature of the barrel within a predetermined range. This device also comprises a temperature sensor to sense the temperature of the barrel in order to activate the control unit for maintaining the predetermined temperature range. Hence, within a predetermined temperature range the infrared source will cycle on and off.

Operating a curler with infrared light requires, inter alia, the use of a transparent barrel for the curler. This is a somewhat costly approach, not necessarily required for all curlers. Curlers with simpler resistive heating, cannot employ the same type of sensor and setup. Further, the circuit allows only to keep one preselected temperature. Individual user needs and habits are not comprehensively addressed.

EP 2 524 617 A2 published after the priority date of the current application discloses a hair styling apparatus with a heating device and a hair protection function. It discloses a temperature-sensing unit, a temperature setting by the user and a moisture sensor in order to select suited temperature for the hair treatment. The moisture sensor comprises two electrodes housed in a base. The hair contact portion of the electrodes and the hair contact surface of the base are disposed below the hair heating surface.

In the US 2001/055501 A1, a hair treatment device, such as a hair straightener, with a temperature control is disclosed. The temperature control has two sensors that are disposed at the outside of the opposing legs of an U-shaped heating surface such, that heating surface and the sensor contact surface of a sensor housing are adjacent to and at level with and/or with step free transition with the heating surface. However, the sensors are provide in a separate senor housing.

The US 2007/0119844 A1 discloses a hair styling device with a tubular heating element. Inside the tubular heating element, two sensors are provided integral with the heating unit.

The present invention attempts to improve these concepts found in the prior art. In particular, the present invention atempts to provide a personal appliance which provides an optimal mode of usage for different users and for different usage situations.

The present invention relates to personal appliances according to claim 1 and is concerned with an improved personal appliance comprising a sensor. In particular, the invention concerns a personal appliance for performing a grooming task on a user, the appliance comprising a grooming element, the grooming element comprising a grooming surface and the appliance comprising a sensor and a sensor housing, the sensor housing comprising a sensor contact surface, wherein the sensor contact surface is adjacent to and at level with the grooming surface.

Fig. 1

shows a hair straightener which is a personal appliance, which implements the present invention.

Fig. 2

shows another schematic representation of another spatial relationship between the above two elements.

Fig. 3

shows yet another spatial relationship between grooming element and two sensor elements.

Fig. 4

shows a scheme illustrating the cooperation of key components of the present invention.

A personal appliance can take a variety of forms. The personal appliance can be can be a grooming appliance, for example a shaver, a trimmer, a beard trimmer, an epilator, or a hair care device, e.g. a curler, a straightener, a brush, a hair dryer, and the like. Depending on the personal appliance the grooming task is different and hence the grooming element and the sensor can be different. Where the personal appliance is a shaver, the grooming element can comprise a hair removing element and can further comprise a heating or cooling element. Such heating or cooling elements can make shaving a more efficient and more pleasant experience. Where the personal appliance is a hair care appliance, the grooming task will typically be the task of drying hair or straightening hair or curling hair. In hair care grooming tasks the temperature at which the task is performed is critical. Therefore, the grooming element will normally be a heating element. In accordance with the present invention the personal appliance is a hair straightener and comprises a grooming element, the grooming element comprising a grooming surface. The grooming surface will be the surface of the grooming element, which is in contact with the skin when the personal appliance is used in the intended manner.

The personal appliance will further comprise a sensor. The choice of the sensor will also depend on the grooming task. Suitable sensors are temperature sensors or humidity sensors or pressure sensors. A temperature sensor, for example can measure the heat of a skin or hair surface which is treated by the grooming element. A humidity sensor can, for example, measure the humidity of hair to be dried. A pressure sensor can measure, for example, the pressure which is applied to the skin or hair, which is treated and on to which pressure is exerted by the grooming element.

In accordance with the present invention the sensor is comprised by a housing and the housing comprises a sensor contact surface. The sensor contact surface is adjacent to (that is in close spatial proximity to) and at level with the grooming surface.

It has been found useful to have sensor contact surface and a grooming surface which are co-planar. Hence, the two surfaces are arranged in one plane.

According to the present invention, the sensor contact surface and the grooming surface are integral. Hence, both surface can be provided from one piece of material and can form part of one larger surface of that piece of material. It has been found useful to provide a sensor housing which comprises a contact plate. The contact plate comprises a front surface and a rear surface. The front surface of the contact plate provides the sensor contact surface. In a further aspect, it has been found useful to use a rear surface which comprises a groove. The sensor can then be at least partially comprised by the groove. If the groove is of suffficient depth and size, the sensor can also be fully comprised by the groove. It has been found useful to provide a groove which is V-shaped.

A groove of declining width, such as and particularly, a V-shaped groove is useful for providing a defined position for sensors and can safely accommodidate sensors of different sizes. The sensors are supported by two wall of the groove and hence make contact with two wall of the groove. Thereby, the sensors are in contact with the sensor housing at least at two points. Such contact normally helpful for increasing the reliability of measurements made with the sensor, for example temperature measurements. In a further important aspect, a groove of declining width, such as and particularly, a V-shaped groove will only have minimal negative impact on the mechanical stability of the sensor housing. In a yet further important aspect, a groove of declining width, such as and particularly, a V-shaped groove will make it easy to position the sensor in a pre-defined position within the groove.

The sensor can be mechanically held down in the groove, for example by a down-holder, for example a spring of the like. Alternatively, but also additionally, the sensor can be held in the groove by an adhesive.

In one embodiment the appliance can comprise two sensor housings and each sensor housing can comprise a sensor contact surface and the sensor contact surfaces can each be adjacent to and at level with the grooming surface. In another embodiment of the present invention comprising two sensor housings both sensor housings are integral with the grooming surface. In such an embodiment, the sensor housings can further be situated at two opposing sides of the grooming surface.

According to the present invention the personal appliance can be a hair care appliance. The appliance can in particular be a straightener.

In some embodiments of the present invention, the data measured by the at least one sensor form a first data set. The first data set comprises a first number of data. In such embodiments a second data set comprising a second number of data can be generated using data from the first data set, the second number being smaller than the first number. In other words, a data set is reduced to a smaller data set. As the smaller data set comprises less data, it in some sense comprises less information. Nevertheless, in relationship to a given question, the data set comprising lesser data can be more meaningful. However, it is critical for providing a meaningful second data set, that the data of the first data set are meaningful. As the data from the first data set come from sensor information, it is important in such situations, that the sensor is arranged to provide reliable data.

In embodiments of the present invention the personal appliance can comprise at least one sensor which measured data, the data forming a first data set comprising data representing a first physical property and wherein a second data set, which comprises data representing a second physical property is generated using data from the first data set and wherein the second physical property is different from the first physical property. In this embodiment, data representing a first physical property, for example temperature, are used to create a data set of data representing another physical property. This other physical property can for example be hair humidity. It has been found, that the hair temperature curves measurable by sensors are representative for hair humidity, as hair responds differently to heat exposure depending on its humidity. Of course, the quality of the data and therefore the mechanical arrangement of the sensors yielding the first data is critical to allow an effective transformation of the first data set to a second data set.

It has been found useful to use two sensors. The two sensors can measure the same property, for example temperature. Two sensors can achieve a more accurate temperature measurement as compared to a single sensor.

Alternatively or additionally, temperature data received from two sensors can be processed for achieving a different quality of information rather than temperature. For example, the temperature difference between the front end and the rear end of the heating plates of a hair straightener can be representative for the dryness of the hair. If the hair is wet, it will normally absorb more heat from the heated plates of a hair straightener, and hence the temperature drop between the front sensor and the rear sensor (in a given stroke direction) is more pronounced. Therefore, a set of temperature data can be transferred into a set of dryness data. Dryness data are referred to as a data set of a different nature as compared to the temperature data set.

In the context of the present invention, a personal applicance is considered useful, wherein the data measured by the at least one sensor form a first data set comprising a data representing a first physical property and wherein a second data set comprising a data representing a second physical property is generated using data from the first data set and the second physical property is different from the first physical property. With reference to the example given above, the first set of data can be temperature data and the second set of data can be dryness data.

In one useful way of practicing the invention, this conversion can be achieved by relying on data stored in the data storage. For example, the data storage may have representative data for temperature drop depending on hair dryness. Hence, by relying on the stored data, it is possible to reliably transform temperature data into dryness data. When the first set of data is created by a single sensor, the quality of the second set of data can be increased by additionally relying on data from the data storage.

It is also possible that the personal appliance comprises a third sensor which measures data of a different nature than the first and the second sensor. For example, in case of a hair straightener, the third sensor may measure hair dryness directly. The data of the third sensor can then be compared with the process data of the first two sensors. The comparison can then lead to an estimate about the reliability of the sensors and to an overall more accurate measurement. Generally, in accordance with the present invention, any sensor, including the third sensor, used in a personal applicance comprising a grooming element can be placed in a groove, for example a groove of declining width, such as and particularly, a V-shaped groove.

Alternatively, the data of the third different sensor can be used to create a data set of yet different quality. For example, when the dryness of the hair is known from data generated by the third sensor, the temperature data generated by the first and second sensor could be used to have an estimate for the speed with which the device is moved through the hair. The third sensor or a fourth sensor could also be a sensor measuring the position of the hair straightener.

Fig. 1 shows a hair straightener, which embodies the present invention. The hair straightener 200 comprises a gripping unit 210. the gripping unit essentially comprises a first arm 212 and a second arm 214. Both arms are linked at joint 216. A cable 218 is provided at one end of the straightener 200. As an interface the straightener comprises a dial knob 220. Further, the straightener 200 comprises a hair treatment unit 230. This hair treatment unit also comprises a first arm 232 and a second arm 234. At one end of the first arm 232 a gripping unit 236 is provided. Both arms comprise heated surfaces and for the second arm 214 the first heating surface 250 can be clearly seen. Adjacent to the first heating surface 250 an area 240 for the first sensor is provided and an area 242 for the second sensor is provided.

Fig. 2 schematically shows an arrangement of a grooming element 10 and a sensor housing 20 according to the present invention.

In this arrangement the sensor housing has a sensor contact surface 22 which is co-planar and even integral with the grooming surface 12. The sensor housing 20 encases the sensor 24. The upper portion of the sensor housing 20 is provided in the form of contact plate 26. Contact plate 26 comprises a front surface, which serves as the sensor contact surface 22 and comprises a rear surface 28.
Fig. 3 represents a useful embodiment of the present invention in a cross-sectional view. The central portion of the combined grooming and sensor housing element is comprised by the grooming element 10. Grooming element 10 comprises the grooming surface 12. Opposite to the grooming surface 12, there is a grooming element rear surface 14. This rear surface 14 can be used to arrange a functional element on it, preferably a heating element 16 as shown. At the right end side of the grooming element 10 a sensor housing 20 is arranged. The sensor housing comprises a sensor contact plate 26 comprising the sensor contact surface 22 and at the opposite side comprises the rear surface 28. The rear surface 28 of the sensor contact plate 26 comprises a groove. This groove is V-shaped, as can be seen on this cross-section. The sensor 24 is arranged in groove 30. Groove 30 is provided deep enough to fully comprise and encase sensor 24. The position of the sensor 24 in groove 30 is secured by hold-down element 32.

On the left hand side a further sensor housing 20A is provided. It is arranged in mirror symmetry to the right hand side sensor housing 20. It also comprises all the elements comprised by sensor housing 20. The corresponding elements are marked with corresponding reference numbers, to which an "A" has been added.

The grooming element 10 is formed as a profile, preferably made from a metal strand casting, which is flat at its front surface for straightening hair and which is provided at its rear side with protruding extensions for separating the heating element (16) from the sensors (24). Those extensions limit the heat emission from the heating element to the senor and increase thus the measuring accuracy of the measured hair temperature. Preferably the the rear surface of the combined grooming and sensor housing element is in the shape of three reversed "U's" - see Fig 5.

Fig. 4 provides a schematic illustration of the functioning of the present invention, without providing actual parts of the invention as embodied in a personal appliance. The personal appliance might generate first sensor data SD1 and second sensor data SD2. Additionally, the user can enter data by a suitable interface, such that further data ED are available. All these data are transmitted to a central processing unit P. This unit will then generate an output signal O, which can be used select a desirable grooming mode.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."