Description AN OVEN

[1] This invention relates to an oven wherein means are provided to control the cooking of the foods which tend to rise during the cooking procedure.

[2] In ovens of the current state of the art, while cooking pastries such as a cake which tend to rise during the cooking process, to be able to control the cooking, it is necessary to detect the increase in height of the food correctly and on time. According to the detected height increase, the operation temperatures and durations of the heaters may be determined. For instance, in ovens wherein several heat sources are utilized, if the height increase of the food rising during the cooking procedure is detected on time, the transition moment from one heat source to another is determined more correctly and a more effective cooking control can be performed. If the mentioned transition moment is not determined correctly, either the cooked food is overdried or the inner portion is left uncooked and energy consumption increases.

[3] In the Japanese Patent Document JP 6113714, a description is given of an embodiment wherein, in an oven, by utilizing a microwave type high frequency heater and a radiative type heater used to crisp the surface of the cake, a two-stage cooking procedure is performed. In the first stage of the cooking procedure, by means of the high frequency heating, the cake is cooked until it rapidly rises whereas in the second stage it gets crispy via radiation. The transition moment from the first stage to the second stage of cooking is decided by a control unit wherein a temperature sensor or a humidity sensor is utilized together with a weight sensor in deciding the mentioned transition moment.

[4] In the International Patent Application WO 2005022144, in a cooking device, ultrasonic transducers are utilized for detecting the cooking wherein the change in the ultrasonic signal permeability of the food is sensed by processing the signals sent via the transmitter. The ultrasonic transmitter located at one side of the cooking container sends a signal whereas the change in the sound frequency is sensed by the receiver located at the other side of the cooking container. When a predetermined value of the mentioned sound frequency change is obtained, it is decided that cooking is finished.

[5] The aim of the present invention is the realization of an oven wherein means are provided to cook food which tends to rise during the cooking procedure in accordance with the user preferences by controlling the height increase inside the cooking container.

[6] The oven realized in order to attain the aim of the present invention is described in the claims.

[7] In the oven of the present invention, in order to cook the pastry such as a cake that

tends to rise during the cooking process and to obtain the surface crispiness preferred by the user, there are provided a microwave, an induction heater or a heater-fan mechanism and such a broiler as an electrical heater or a halogen lamp which operates within the principles of radiation to make the surface of the foods crispy. The height change of the upper surface of the food rising during the cooking process is detected by means of an ultrasonic sensor wherein a microprocessor evaluating the signals received from the mentioned ultrasonic sensor decides when the broiling and heating elements will be activated and deactivated.

[8] The ultrasonic sensor comprises a transmitter which sends sound waves at a certain frequency to the upper surface of the cooked food and a receiver sensing the change in the duration of reflection and magnitude of the sound waves which return by being reflected from the upper surface of the food, wherein said transmitter and receiver are positioned side by side at the ceiling of the cooking chamber so as to face the middle portion of the cooked food.

[9] Since the ultrasonic sensor is not affected by the color change of the cooked food, in the embodiment of the present invention, a better result is obtained compared to o ther embodiments where infrared or similar level sensors are utilized.

[10] By means of the ultrasonic sensor, the cooking control is performed in a more effective manner wherein pastries like cakes etc. are cooked with the desired level of rising, surface color, crust thickness and hardness preferred by the user, as the transition moment from the rising to broiling is determined correctly.

[11] The oven realized in order to attain the aim of the present invention is illustrated in the attached figures where:

[12] Fig.l - is a schematic representation of an oven.

[13] Fig.2 - is a front view of an oven.

[14] Elements shown in figures are numbered as follows:

[15] 1. Oven

[16] 2. Cooking chamber

[17] 3. Food container

[18] 4. Heater

[19] 5. Broiler

[20] 6. Ultrasonic sensor

[21] 7. Microprocessor

[22] 8. Transmitter

[23] 9. Receiver

[24] The oven (1) comprises a cooking chamber (2) where cooking procedure is performed, a food container (3) which is placed into the cooking chamber (2) and into which such foods as pastries like cakes etc. that tend to rise during cooking are placed

to be heated or cooked and, a microwave or induction heater (4) or a heater - fan mechanism whereby foods in the food container (3) are cooked.

[25] The oven (1) in accordance with the present invention, further comprises an ultrasonic sensor (6) used to detect the height change of the upper surface of the food rising during the cooking procedure and a microprocessor (7) which controls the cooking procedure by evaluating the signals received from the ultrasonic sensor (6).

[26] The ultrasonic sensor (6) incorporates a transmitter (8) which sends sound waves at a certain frequency to the upper surface of the cooked food and, a receiver (9) which detects the change in the duration of reflection and magnitude of the sound waves sent by the mentioned transmitter (8) and return by being reflected by the upper surface of the cooked food.

[27] By evaluating the sound wave sent by the transmitter (8) and received by the receiver (9), the microprocessor (7) decides that the rising of the surface of the cooked food is continuing if it monitors a change in the duration of reflection and magnitude of the sound waves sent by the transmitter (8) and received by the receiver (9) and, decides that the rising of the surface of the cooked food is completed if it monitors a decrease in the change in the magnitude of the sound waves and in the duration of the reflection or that the magnitude of the sound waves and the duration of the reflection continues constantly without being changed.

[28] The ultrasonic sensor (6) is positioned at the ceiling of the cooking chamber (2) so as to face the middle portion of the cooked food where the rising of the food is sensed effectively, in such a manner that the transmitter (8) and the receiver (9) are located side by side. Thereby, it is achieved that the sound waves sent by the transmitter (8) and reflected by the surface of the food are detected by the receiver (9) effectively .

[29] In another embodiment of the present invention, the oven (1) further comprises such a broiler (5) as an electrical heater or a halogen lamp which operates within the principles of radiation whereby the surface of the foods gets crispy.

[30] In that embodiment, in the oven (1), a two-stage cooking procedure is performed in order to cook such a pastry as a cake that tends to rise during the cooking process. In the first stage of the cooking, the heater (4) is activated to cook the pastry and the food starts to rise during this period. The increase in the height of the food as it rises is detected by means of the ultrasonic sensor (6) and signals are sent to the microprocessor (7). When the microprocessor (7) decides that the rising of the surface of the cooked food is finished, it starts the second stage of the cooking procedure by deactivating the heater (4) and operating the broiler (5). By means of the broiler (5), the surface of the food which is risen in the first stage of the cooking procedure and the height of which now at the maximum level, is crisped.

[31] The ultrasonic sensor (6) stays activated from the beginning of the cooking until the

transition to the broiling stage and is deactivated after this transition as the broiler (5) being operated. Thereby, since the ultrasonic sensor (6) and the broiler (5) which are positioned at the ceiling of the cooking chamber (2) near each other, operate at different times, it is prevented that they affect each other.

[32] In an oven (1) where cooking procedure is respectively performed by means of such a heater (4) as a magnetron and a broiler (5) operating within the principles of radiation, the ultrasonic sensor (6) is activated at the instant where the first stage of the cooking procedure is started for such a food as a cake which tends to rise and is placed into the food container (3) and the height change of the cake dough is started to be detected. Depending on the change in the duration of reflection and the magnitude of the sound wave that is reflected by the surface of the cake, signals are sent from the receiver (9) part of the ultrasonic sensor (6) to the microprocessor (7). According to the signal received from the receiver (9), by means of the microprocessor (7), process control is achieved. In the first stage of the cooking procedure, the cake dough is rapidly cooked as it rises as a result of the operation of the heater (4). In the vicinity of the outer surface of the cake dough, free water evaporates at the boiling temperature. From that moment, crust formation is observed on the cake dough. The crust formed does not permit the dough to further rise and following the mentioned crust formation, rising stops. As the rising decelerates and eventually stops, the magnitude of the sound wave being reflected by the surface and the duration of reflection sensed by the ultrasonic sensor (6) do not change. As no change is noticed in the incoming signals, the microprocessor (7) starts the second stage of the cooking process wherein the microprocessor (7) deactivates the heater (4) and activates the broiler (5). In this part of the procedure, the ultrasonic sensor (6) is deactivated. The second stage of the cooking procedure, wherein the surface of the cake is crisped, ends at an instant in relation to the surface crispiness preferred by the user.

[33] In the oven (1), the object of the present invention, the cooking control is effectively performed by means of the ultrasonic sensor (6) wherein it is achieved to control the cooking procedure of such foods as patty for which rising is not preferred as well as of such foods as cake for which rising is preferred. The ultrasonic sensor (6) correctly detects the height increase without being affected by the color change during the cooking procedure. It is accomplished to save energy by decreasing the cooking time and to cook such pastries as cake with preferred puffiness, surface color, crispiness, thickness and hardness since broiling is performed on time as the rising is completed.