EP2798273A1

EP2798273A1 - Oven with optical detection means

Info

Publication number: EP2798273A1
Application number: EP12808271.6A
Authority: EP
Inventors: Oner Hatipoglu; Gokhan Yildiz
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2011-12-26
Filing date: 2012-11-26
Publication date: 2014-11-05
Also published as: WO2013098004A1

Abstract

The present invention relates to an oven (1) comprising an exterior body (2), a cooking cavity (3) wherein the cooking process is performed and an optical detection means (4) that is located in the cooking cavity (3) and provides the detection of the data about a target (H) such as the cooked food or the tray whereon the food is placed and that has a transmitter (5) which sends light waves onto the target (H), a receiver (6) which detects the light waves reflected from the target (H), and a casing (7) which is located at the upper side of the cooking cavity (3) and whereon the transmitter (5) and receiver (6) are mounted side by side so as to face the cooking cavity (3).

Description

OVEN WITH OPTICAL DETECTION MEANS

The present invention relates to an oven comprising an optical detection means that is used for distance measurement or remote temperature measurement.
In the state of the art, optical detection systems are used in ovens for detecting the tray position, detecting the rise amount of the food in case that the cooked food is a pastry such as cake or detecting the surface temperature or color change of the food. Optical detection systems generally consist of a transmitter-light source or a receiver-light sensor pair. In optical detection systems, the light waves generated in the transmitter are sent in the direction of the target inside the oven, for example onto the cooked food or onto the tray whereon the food is placed, and the light is provided to be reflected from the target and the reflected light is converted into electrical signal by being projected onto the receiver. The optical detection systems are generally placed into a casing integrated onto the upper wall or side wall of the cooking cavity of the oven and are protected against high temperature by providing thermal insulation. In the ovens (1’) wherein the optical detection means (4’) is used, a transparent plate (8’) such as a glass plate having high resistance against heat is placed between the environment wherein the receiver (6') and the transmitter (5') are situated, and the cooking cavity (3'). The transparent plate (8’) provides the light generated by the transmitter (5’) to be transmitted to the target (H’) located in the cooking cavity (3') and the light reflected from the target (H’) to be transmitted to the receiver (6’) and at the same time, the transmitter (5') and the receiver (6') to be protected against the high temperature and humidity; however, the transparent plate (8’) also causes undesired light reflections between the transmitter (5’) and the receiver (6’) (Figure 1). Some of the light generated by the transmitter (5’) and directed from the transparent plate (8’) to the target (H’) is reflected from the transparent plate (8’) before being reflected from the target (H’) and the beams reflected from the target (H’) and the transparent plate (8’) reach the receiver (6’) by mixing with each other and cause the receiver (6’) to make false detections.
In the Japanese Patent Application No. JP56000934, a cooker is described that comprises an optical arrangement consisting of a light source and a light sensor, and a glass plate which is placed between the optical arrangement and the cooking chamber.
In the Japanese Patent Application No. JP2006242420, a heating cooker is described that comprises a LED and an infrared sensor which are arranged in the upper part of a cookroom.
The aim of the present invention is the realization of an oven wherein the optical detection means placed onto the cooking cavity is provided to make error-free measurements.
The oven realized in order to attain the aim of the present invention and explicated in the first claim and the respective claims thereof, comprises an optical detection means having a transmitter which is placed at the upper side of the cooking cavity and sends light waves onto a target inside the cooking cavity such as food or tray, a receiver which detects light waves reflected from the target and a casing whereto the transmitter-receiver pair is mounted. A glass plate is placed between the optical detection means and the cooking cavity in an inclined manner so as to prevent the beams sent from the transmitter from being reflected directly onto the receiver.
In an embodiment of the present invention, the transparent plate is placed at the lower side of the transmitter and receiver in an inclined manner so as to face the transmitter, and thus, the beams reflected from the upper surface of the glass plate are provided to be blocked inside the casing.
In another embodiment of the present invention, a separator, which separates the transmitter and receiver areas, is placed between the inclined transparent plate and the casing. The upper edge of the separator contacts the casing between the transmitter and the receiver, and the lower edge of the separator contacts the transparent plate. The separator extends in the vertical direction in an inclined manner so as to move away from the transmitter and thus, does not limit the field of view of the transmitter.
In an embodiment of the present invention, the transmitter is a LED light source generating visible light, and the receiver is a photo-detector detecting the visible beams.
In another embodiment of the present invention, the transmitter is an infrared LED light source generating infrared beams, and the receiver is an infrared sensor. In this embodiment, a transparent plate, which transmits the infrared light with certain wavelengths, is used in the oven.
In another embodiment of the present invention, a light barrier surrounding the receiver is integrated to the casing that carries the optical detection means, and the receiver is provided not to be exposed to other beams reflected from the environment.
In the oven of the present invention, by means of the transparent plate placed under the optical detection means in an inclined manner, the beams reflected from the upper surface of the transparent plate are prevented from reaching the receiver and the receiver is provided to be exposed only to the beams reflected from the food inside the cooking cavity or from the tray, and thus, to make accurate measurements.
The oven realized in order to attain the aim of the present invention is illustrated in the attached figures, where:
Figure 1 - is the schematic view of a state of the art oven.
Figure 2 - is the schematic view of the oven of the present invention.
Figure 3 - is the schematic view of the optical detection means in an embodiment of the present invention.
Figure 4 - is the schematic view of the optical detection means in another embodiment of the present invention.
The elements illustrated in the figures are numbered as follows:

Oven
Exterior body
Cooking cavity
Optical detection means
Transmitter
Receiver
Casing
Transparent plate
Separator
Light barrier

The oven (1) comprises an exterior body (2), a cooking cavity (3) wherein the cooking process is performed, and an optical detection means (4) which is located in the cooking cavity (3) and provides the detection of data such as the surface temperature, color change or position about the target (H) defined as the cooked food or the tray whereon the food is placed, and the control of the cooking process according to the data received from the target (H).
The optical detection means (4) comprises a transmitter (5) which sends light waves onto the target (H), a receiver (6) which detects the change in the intensity of the light waves that are sent by the transmitter (5) and that return by being reflected from the target (H), and a casing (7) which is located at the upper side of the cooking cavity (3) and whereon the transmitter (5) and receiver (6) are mounted side by side so as to face the cooking cavity (3).
The oven (1) of the present invention comprises a transparent plate (8) such as a glass plate which is placed between the optical detection means (4) and the cooking cavity (3) in an inclined manner with respect to the horizontal plane formed by the transmitter (5) and the receiver (6), thus, which prevents the beams, sent from the transmitter (5) and reflected from the upper surface thereof before entering the cooking cavity (3), from affecting the receiver (6) by diverting them.
The transparent plate (8) that is used in the oven (1) and placed between the optical detection means (4) and the cooking cavity (3) directs the beams generated in the transmitter (5) to the target (H) by refracting them to a degree according to the refraction index of the material it is produced from, and directs the beams reflected from the target (H) to the receiver (6). The transparent plate (8), furthermore, prevents the optical detection means (4) from being affected by the high humidity and temperature in the cooking cavity (3). Some of the beams generated in the transmitter (5) and directed to the target (H), for example 10% of them, does not pass through the transparent plate (8) and are reflected back from the upper surface of the transparent plate (8). In the embodiment of the present invention, since the transparent plate (8) is placed in an inclined manner, the “undesired” beams reflected upwards from the upper surface are diverted by the transparent plate (8) and prevented from reaching the receiver (6) and thus, the receiver (6) is not exposed to light reflections that can cause it to make wrong detections and the receiver (6) makes accurate measurements by detecting only the beams reflected from the target (H).
In an embodiment of the present invention, the transparent plate (8) is placed at the lower side of the transmitter (5) and receiver (6) so as to face the transmitter (5) and such that the vertical distance (h1) between the transparent plate (8) and the transmitter (5) is greater than the vertical distance (h2) between the transparent plate (8) and the receiver (6), and the transparent plate (8) extends from the level of the transmitter (5) to the level of the receiver (6) by rising (Figure 3).
In this embodiment, most of the beams sent from the transmitter (5) and reflected from the transparent plate (8) are directed to the lower surface of the casing (7) by being diverted and thus, the reflected beams are substantially prevented from reaching the transmitter (5). Furthermore in this embodiment, the beams reflected from the transparent plate (8) do not project out beyond the optical detection means (4) and are blocked between the transparent plate (8) and the casing (7).
In another embodiment of the present invention, the oven (1) comprises a separator (9) which extends between the transparent plate (8) and the casing (7) and separates the transmitter (5) and receiver (6) areas in the optical detection means (4), and the upper edge of which contacts the casing (7) between the transmitter (5) and the receiver (6) and the lower edge of which contacts the transparent plate (8), and which is produced from light-proof material such as plastic or metal (Figure 4). In this embodiment, the beams that are sent from the transmitter (5) and reflected from the transparent plate (8) are almost completely prevented from reaching the receiver (6). The separator (9) extends between the casing (7) and the transparent plate (8) in an inclined manner so as to move away from the transmitter (5) in the vertical direction. The separator (9) does not narrow down the visual field range of the transmitter (5) and furthermore, full contact is provided between the lower and upper edges of the separator (9), and the lower surface of the casing (7) and the upper surface of the transparent plate (8) and thus, light leaks are prevented.
In another embodiment of the present invention, the transmitter (5) is a LED light source generating visible light, and the receiver (6) is a photo-detector detecting the visible beams reflected from the target (H).
In another embodiment of the present invention, the transmitter (5) is a LED light source generating infrared light, and the receiver (6) is an infrared sensor detecting the infrared beams reflected from the target (H). In this embodiment, the oven (1) comprises a transparent plate (8) produced from glass material which transmits the infrared beams having certain wavelengths, for example wavelengths between 500 nanometers and 2.5 micrometers (2500 nanometers).
In another embodiment of the present invention, the optical detection means (4) comprises a light barrier (10) which is produced from light-proof material, mounted to the casing (7) and surrounds the receiver (6), and which prevents the beams reflected from the outer environment from affecting the receiver (6) (Figure 4). In the optical detection means (4), the environmental light reflections affecting the receiver (6) are minimized and there is a high probability that data can be obtained from the target (H).
In the oven (1) of the present invention, by means of the transparent plate (8) placed between the optical detection means (4) and the cooking cavity (3) in an inclined manner, the beams sent from the transmitter (5) and reflected from the upper surface of the transparent plate (8) are prevented from reaching the receiver (6) and almost only the beams reflected from the target (H) are provided to reach the receiver (6). The receiver (6) is protected from the undesired light reflections and measurement errors are minimized.
It is to be understood that the present invention is not limited by the embodiments disclosed above and a person skilled in the art can easily introduce different embodiments. These should be considered within the scope of the protection disclosed by the claims of the present invention.

Claims

An oven (1) comprising an exterior body (2), a cooking cavity (3) wherein the cooking process is performed, an optical detection means (4) that is located in the cooking cavity (3) and provides the detection of the data about a target (H) such as the cooked food or the tray whereon the food is placed and that has a transmitter (5) which sends light waves onto the target (H), a receiver (6) which detects the light waves reflected from the target (H), and a casing (7) which is located at the upper side of the cooking cavity (3) and whereon the transmitter (5) and receiver (6) are mounted side by side so as to face the cooking cavity (3), characterized in that a transparent plate (8) which is placed between the optical detection means (4) and the cooking cavity (3) in an inclined manner with respect to the horizontal plane formed by the transmitter (5) and the receiver (6).
An oven (1) as in Claim 1, characterized in that the transparent plate (8) that is placed at the lower side of the transmitter (5) and receiver (6) so as to face the transmitter (5) and such that the vertical distance (h1) between the transmitter (5) and the transparent plate (8) is greater than the vertical distance (h2) between the receiver (6) and the transparent plate (8).
An oven (1) as in Claim 1 or 2, characterized in that a separator (9) which extends between the casing (7) and the transparent plate (8) and separates the transmitter (5) and receiver (6) areas in the optical detection means (4).
An oven (1) as in Claim 3, characterized in that the separator (9), the upper edge of which contacts the casing (7) between the transmitter (5) and the receiver (6), and the lower edge of which contacts the transparent plate (8) and which is produced from light-proof material.
An oven (1) as in Claim 3 or 4, characterized in that the separator (9) which extends between the casing (7) and the transparent plate (8) in an inclined manner so as to move away from the transmitter (5) in the vertical direction.
An oven (1) as in any one of the above claims, characterized in that the transmitter (5) that is a LED light source generating visible light, and the receiver (6) that is a photo-detector detecting the visible beams reflected from the target (H).
An oven (1) as in any one of the Claims 1 to 5, characterized in that the transmitter (5) that is a LED light source generating infrared light, and the receiver (6) that is an infrared sensor detecting the infrared beams reflected from the target (H).
An oven (1) as in Claim 7, characterized in that the transparent plate (8) that is produced from glass material which transmits the infrared beams having certain wavelengths.
An oven (1) as in any one of the above claims, characterized in that the optical detection means (4) that has a light barrier (10) which is produced from light-proof material, mounted to the casing (7) and surrounds the receiver (6).