Claims:I CLAIM

1. A compact automatic food dryer (5) programmed for multiple food items comprising an inner cabinet (8), a pre- programmed microcontroller outside the inner cabinet (8), a Load cell (10), a heater element interfaced with the preprogrammed microcontroller, a temperature sensor interfaced with the preprogrammed microcontroller, an air blower interfaced with the preprogrammed microcontroller, a cooling fan (17) and a user interface (2) to display as well as accepting the input of dynamics of food dryer
WHEREIN:
- Moisture in food item is not sensed using moisture sensor but a continuous measurement of weight reduction percentage calculation using the load cell (10) is utilized to measure moisture content in food item;
- Load cell (10) is fitted outside the inner cabinet (8) and is attached with the means of a mechanical weight transfer link (9) via a through hole (14) available over the inner plane surface (15) of the inner cabinet (8).

2. The compact automatic food dryer (5) as claimed in claim 1 WHEREIN :
- Weight of the sample over the said sliding trey (6) inside the drying compartment is transferred to the load cell (10) placed outside the drying compartment through the means of mechanical weight transfer link (9);
- Load cell (10) provides an analog voltage proportional to weight of the sample and further transfers to the microcontroller;
- A continuous measurement of weight reduction percentage calculation using the load cell (10) is done and is forwarded to the microcontroller for setting the heating conditions within the inner cabinet (8) accordingly;
- The preprogrammed microcontroller consists of pre fed drying conditions of various food items to be dried and inputting the favorable temperature of the sample to be dried via the user interface (2).

3. The compact automatic food dryer (5) as claimed in claim 1 WHEREIN :
- A flexible diaphragm (16) made of any suitable flexible material and of negligible stiffness is fixed between the inner cabinet (8) and the means of mechanical weight transfer link (9) for restricting escape of air through the drying compartment;
- A first air vents (3) is maintains a uniform flow of moist air out of food dryer;
- A second air vents (12) prevents overheating of circuitry and the load cell (10).

4. The compact food dryer (5) as claimed in claim 1 WHEREIN the method of performing the drying operation consists of following steps:
- Open the compact food dryer (5) by the handle (4) and putting the sample over the plurality of the sliding treys (6);
- Setting the favorable temperature using user interface (2);
- As preprogrammed in the console of the microcontroller for instructions to various components for further drying process till completion, initiating the sensing operation of the initial temperature of the drying compartment by the temperature sensor and setting the duty cycle of the heater element within the drying compartment as per the defined algorithm below
(i) If (favorable temperature – initial temperature) > 5, duty cycle = 100%;
(ii) If (favorable temperature – initial temperature) < -5, duty cycle = 0%;
(iii) If -5 < (favorable temperature – initial temperature) < 5, duty cycle = (50 + (favorable temperature – initial temperature)*10) %.
- Obtaining voltage corresponding to weight of the sample from the load cell (10) as a continuous measurement of weight at a predefined interval ‘t’ as per the weight data reverted by the load cell (10);
- Multiplying with a gain of 128;
- Performing A to D conversion using A to D converter chip;
- Storing in FIFO register for predefined ‘n’ elements a[0], a[1], a[2]….a[n-1] wherein a[0] corresponds to first measured weight of the sample, a[1] corresponds to second measured weight of the sample at a predefined interval of ‘t’ seconds from the first sample a[0] and so on;
- Performing percentage weight reduction (PWR) calculation between latest value and the last value of FIFO register as per the defined formula

Percentage Weight Reduction (PWR) = 100*(abs (a[0] - a[n-1])/a[n-1]);

- Comparing the percentage weight reduction (PWR) with defined ideal percentage weight reduction (PWR) of the sample and repeating the percentage weight reduction (PWR) calculation for the next weight reading if the computed percentage weight reduction (PWR) of the sample comes out to be more than ideal percentage weight reduction (PWR);
- Increasing a count value by one and repeating the percentage weight reduction (PWR) calculation for the next weight reading if the count value comes out to be less than defined minimum number of iterations to be performed;
- Instructing the heater element to turn off if the count value comes out to be more than defined minimum number of iterations to be performed;
- Displaying the completion of drying process via user interface (2) and;
- Taking the sample out of the compact automatic food dryer (5).

KOMPAL BANSAL (PA NO. 1754)
Dated: January 17, 2018 PATENT AGENT FOR THE APPLICANT

, Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

COMPACT AUTOMATIC FOOD DRYER AND METHOD OF USE THEREOF

SICKLE INNOVATIONS PRIVATE LIMITED
I-1, VENTURE SPACE
CIIE BUILDING, IIMA NEW CAMPUS
VASTRAPUR, AHMEDABAD-380015
GUJARAT
INDIA

The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF INVENTION
The present invention relates broadly to the field of food drying devices using electronic means. More specifically, it pertains to a compact automatic food dryer and method of use thereof.
BACKGROUND OF THE INVENTION
Food has to be dried to particular moisture level to avoid over or under drying. Some spices like saffron has to be dried at a suitable temperature and quickly to retain the critical ingredients for produce good quality. Conventional methods like solar drying take up lot of time and oven dryers can over dry causing the saffron to degrade.
Common practices include to dry the food naturally under the sun in open air. Such method is time consuming, the condition is not controllable, and the food is subject to contamination.
Food dehydrating devices have been developed for drying food products by artificial means in which the food is subjected to low heat and air stream applied slowly to it over an extended period of time. The main drawback of known dehydrators is the degree of dehydration cannot be controlled or adjusted. Another problem is the individual operating the food dehydrator must visually observe the food pieces during dehydration to turn the dehydrator off once a satisfactory level of dehydration has been accomplished since excessive dehydration results in degradation or loss of key ingredients of the food produce like saffron. Excessive dehydration also consumes an excessive amount of electrical energy, thus losing a certain degree of efficiency.
Attempts have been made to find the moisture level in the substance by weight of the product as a tool to determine the moisture content of a product. This method is known as gravimetric method but determining moisture level depends on the initial state of the food which cannot be identified unless completely dried. Hence it is not enough and an innovative approach is needed to control the dehydration and stop once the product is dried as per requirements. The real time measurement of moisture content from the sensor in the drying chamber is not an indicative of the moisture content of the food as it depends on widely varying parameters like type of food, thickness, dryness , temperature and air used etc.
Apart from above mentioned limitations, other problem such as calibration of the weight sensor frequently occurs because of placing the weight sensor inside the drying compartment for calculating the moisture reduction generally heats up due to heater operation thereby providing the wrong indication of weight and so is the moisture content. This may become a severe problem as some spices need continuous monitoring of weight and displaying the false weight will provide the wrong calculation of moisture which may over burn or under burn the sensitive sample like spices. General sensors are not calibrated for high temperatures and the ones which are calibrated to operate are quite expensive.
Solution offered by the present invention
In order to resolve the problem faced earlier, the inventors have developed a compact automatic food dryer programmed for multiple food items wherein the food items is placed within drying compartment over a sliding/removable tray suspended with a mechanical weight transfer means connected to a load cell. A flexible diaphragm used between drying compartment and mechanical transfer means restricts the escaping of hot air from drying compartment. As per initial temperature of compartment by sensor, duty cycle of heater is varied by microcontroller. Measured weight is continuously transferred to the load cell which is placed outside the drying compartment which converts sample weight into appropriate analog voltage. The load cell communicated with a microcontroller chip embedded outside drying compartment keeps converting obtained analog voltage value into 24 bit digital voltage value and stored in FIFO register within microcontroller and at a predefined intervals a percentage weight loss is calculated from latest value and last value of FIFO register and compared with ideal percentage weight loss as defined in microcontroller. Whole process is repeated for predefined iterations. The microcontroller accordingly sets the heat intensity within drying compartment.

PRIOR ART PATENTS/ RESEARCH ARTICLES
S no. Prior Arts Comparison with present invention
1. US4316384- Disclosed prior art is detailed upon the measuring the moisture content continuously and using the input to control the drying intensity The prior art does not define the cutting off parameter which becomes crucial for expensive and delicate food articles such as saffron. Moreover, the prior art does not use the method of placing weight sensor outside the drying compartment utilized for percentage weight reduction using microcontroller means.
2. US 4889201- Disclosed prior art uses a balance scale and a digital evaluating unit for calculating the moisture level. It proposes a method that cuts off the drying at the right moisture level. However, it uses the inflection point as a base for reference. Using the inflection point as mentioned in the prior art is not guaranteed to be obtained if partly dried food is placed limiting its scope. Moreover, the sample size, if varied, will give different inflection points hence the system inherently generates error and practically cannot be used for sensitive applications like saffron. Also, the prior art does not use the method of placing weight sensor outside the drying compartment utilized for percentage weight reduction using microcontroller means.
3. CN 201365509 Y- The prior art discloses a drying house for automatically controlling dehydration and drying of food, comprising a drying room, baking vehicle and a running track. It comprises automatic temperature controller, humidity control, product weight recoding, and an alarm which operate together. Baking procedure for temperature change, humidity change and weight change is set in the computer to accurately master the baking yield of the product so as to automatically control the temperature and the humidity inside the drying room and the baking yield of the product and ensure stable flavor of the baking product. The prior art uses various sensors connected with a computer for monitoring the internal conditions of the dryer and setting the internal temperature accordingly. The difference with the present invention lies in placing the weight sensor. The prior art places a weight sensor inside the drying compartment which can harm it during the drying process thereby yielding the error in measurement whereas in the present invention, weight sensor is kept outside the drying compartment. Moreover, in the present invention, utilization of moisture using moisture sensor is eliminated by calculating the percentage weight reduction in the sample.
4. US 7441443 B2- The prior art discloses a drying balance including a pan that rests on a weighing system as well as a heat source for drying and drying a sample on the pan. A sensor measures the absorption coefficient, transmission coefficient, or reflection coefficient of the sample in at least one predefined spectral range, or measures the moisture dependent dielectric constant of the sample while the weighing system measures the moisture dependent weight of the sample. The drying balance allows the entire calibration curve of the sensor to be determined in a single drying process. The difference lies in the fact that the prior art uses a weight sensor placed within the drying compartment which can affect its working due to heat during drying process whereas in the present invention weight sensor is placed outside the drying compartment and weight transfer means is connected between food tray and weight sensor.

No relevant patent was found in Indian patent database.
Therefore, it can be concluded from the above that in spite of all the efforts made, the solutions previously proposed and known in the prior art do not meet all the essential requirements which are taken into consideration in the present invention.
OBJECTS OF THE INVENTION

The primary object of the present invention is to disclose a compact automatic food dryer for moisture control using percentage weight reduction method.
One more object of present invention is to disclose a compact automatic food dryer for moisture control which is so designed that it eliminates the chances of weight sensor to getting damaged during the working of the dryer due to heat.
SUMMARY OF THE INVENTION
The proposed invention is a compact automatic food dryer programmed for multiple food items wherein the food items are placed within drying compartment over a sliding/removable tray suspended with a mechanical weight transfer means connected to a load cell. A flexible diaphragm used between drying compartment and mechanical transfer means restricts the escaping of hot air from drying compartment. As per initial temperature of compartment by sensor, duty cycle of heater is varied by microcontroller. Measured weight is continuously transferred to the load cell which is placed outside the drying compartment which converts sample weight into appropriate analog voltage. The load cell communicated with a microcontroller chip embedded outside drying compartment keeps converting obtained analog voltage value into 24 bit digital voltage value and stored in FIFO register within microcontroller and at a predefined intervals a percentage weight loss is calculated from latest value and last value of FIFO register and compared with ideal percentage weight loss as predefined in microcontroller. Whole process is repeated for predefined iterations. The microcontroller accordingly sets the heat intensity within drying compartment.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig 1: Proposed Automatic Food Dryer
1. Outer body
2. User Interface
3. First Air Vents
4. Handle
5. Dryer
Fig 2: Inner view of Automatic Food Dryer
1. Outer body
2. User Interface
3. First Air Vents
4. Handle
5. Dryer
6. Sliding Tray
7. Suspended tray support
8. Inner cabinet
Fig 3: Weight Transfer Mechanism Using Load Cell
2. User Interface
3. First Air Vents
4. Handle
5. Dryer
9. Mechanical Weight Transfer Link
10. Load Cell
11. Back Panel
12. Second Air Vents
13. Mounting Board
14. Through Hole
15. Inner Plane Surface
Fig 4: Cross-Sectional View of Dryer
1. Outer body
5. Dryer
6. Sliding Tray
8. Inner cabinet
9. Mechanical Weight Transfer Link
10. Load Cell
11. Back Panel
15. Inner Plane Surface
16. Flexible Diaphragm
17. Cooling Fan

DETAILED DESCRIPTION OF THE INVENTION
The present invention resolves all the shortcomings described in the prior arts and gives an apparatus and a method to dry or dehydrate delicate food articles that require uniform heat at a set temperature for right drying.
Figure 1 displays the invented dryer (5) comprising of a heater element (not shown), Air Blower (not shown), handle (4), user interface (2) to control the dynamics of the dryer (5), first air vents (3) are designed to maintain a unifrom flow of moist air out of the dryer. Whole system is encased in an outer body (1). The said heater element (not shown) and air blower (not shown) are controlled using a preprogrammed micro controller (not shown) taking the inputs of load (sample) and temperature to maintain the required temperature and to turn off the system when desired drying is obtained so that the product does not under dry or over dry. End of drying is obtained by comparing the percentage of weight loss calculated using weight at that instance, if it matches the preprogrammed percentage defined in the microcontroller then the microcontroller informs via user interface (2) about completion of drying process. The dryer (5) is designed to dry large quantities of material on the plurality of sliding trays (6). The entire sensing of rate of moisture loss from the sample is based on the load cell (10) that is placed outside of the inner cabinet (8) so that the temperature inside the chamber does not affect the calibration of the load cell (10). The load cell (10) is also ventilated from all the sides to prevent any accumulation of heat thereby eliminating the chances of malfunctioning.
Figure 2 shows the internal structure of dryer (5) compriseing a plurality of sliding trays (6) which are made up of food grade perforated steel and are designed to slide forward in order to place the food to be dried. The food is dried inside the inner cabinet (8) which is again made of food grade steel. Plurality of sliding trays (6) are connected through a Suspended tray support (7). Inner cabinet (8) also contains a temperature sensor (not shown) and a drying element (not shown) which are in direct communication with the microcontroller.
Figure 3 displays upper part connection within dryer (5). A mechanical weight transfer link (9) is used to suspend plurality of trays (6) via a through hole (14) over inner plane surface (15). The midpoint of the mechanical weight transfer link (9) over inner plane surface (15) is connected to a load cell (10). As the load cell (10) resides outside the inner cabinet (8) over the inner plane surface (15), inner cabinet (8) heat during food drying cannot damage the load cell (10). This mechanical arrangement of mechanical weight transfer link (9), load cell (10) and sliding trays (6) transfers the weight from the sliding trays (6) to the load cell (10).
The microcontroller (not shown) is placed at the mounting board (13) which contains FIFO registers, appropriate A/D convertors, gain multipleirs using adders, various relays, memory units and initial defined ideal moisture contents of various food items and spices which needs to be dried.
Upon placement of the food item to be dried, the load cell (10) signals the microcontroller chip (13) mounted on the mounting board (13) which converts the signal from analog to digital. The back panel (11) protects the electric circuits mounted on the mounitng board (13) and comprises of plurality of second air vents(12) that prevents the circuits from bring overheatted and allows the cooling fan (17) to take in air. The readings obtained from the sensors are sent to microcontroller that displays the programmed data on display panel over user interface (2).
Figure 4 shows a crossectional view of the dryer (5). The sliding tray (6) is suspended from the top roof of the inner plane surface (15) within inner cabinet (8) through a flexible diaphram (16). The flexible diaphram (16) is made of very flexible material and with negligible stiffness. The main purpose of flexible diaphram (16) is to stop the air escape via a through hole (14) and since because of its negligible stiffness, it does not interfere with the measurements of the load cell (10).
Method of use of the system
The ideal moisture percentage of the sample is defined in the microcontroller. As an example, saffron is used as a sample to be dried in a controlled way. As per the experimental data, 50 to 500 grams can be dried in 10 min to 45 min. Drying operation for other food or spices is defined in the microcontroller. User need to set the drying operation specific to the sample using user interface (2).
Step 1:-Sample placement and Initial temperature adjustment of dryer compartment by microcontroller
As an example, saffron is used as a sample to be dried.
Initially the sample is kept inside the dryer (5) over the sliding tray (6). A temperature is set to 60C by user interface (2) which is ideal for drying saffron. Actual temperature of chamber is measured by temperature sensor (not shown) using serial communication. The difference in temperature is calculated and heater element is actuated based on following rules:-
(1) If (set temperature – initial temperature) > 5 then duty cycle for heater element is 100% as set by microcontroller.
(2) If (set temperature – initial temperature) < -5 then duty cycle of heater element is 0% as set by microcontroller.
(3) If -5 < (set temperature – initial temperature) <5 then duty cycle of heater element is (50+( set temperature – initial temperature)*10)% as set by microcontroller.
Step 2:-Weight calculation using load cell and data transfer to microcontroller
Weight of saffron is measured using load cell (10) which provides an analog voltage proportional to weight of the sample. Within microcontroller, voltage is multiplied with a gain of 128 and A to D conversion is done using A to D converter chip as defined in microcontroller chip. The digital value obtained is read by microcontroller using shift in register.
Step 3:-Weight percentage reduction calculation by microcontroller using stored data
Continuous measurement of weight by microcontroller is done at a predefined interval ‘t’ as per the weight data reverted by load cell (10). Weight measured are stored in FIFO array of predefined ‘n’ elements a[0], a[1], a[2]….a[n-1] wherein a[0] corresponds to first measured weight of the sample, a[1] corresponds to second measured weight of the sample at a predefined interval of ‘t’ seconds from the first sample a[0], a[2] corresponds to third measured weight of the sample at the interval of next ‘t’ seconds from the second sample a[1] and so on. This overall ‘n’ samples corresponds to data recording of n*t seconds. At every ‘t’ seconds new entry come and whole array is shifted one value right. In this way FIFO always stores latest ‘n’ readings from load cell (10). Also at every ‘t’ seconds, percentage weight loss is calculated between latest value FIFO and last value of FIFO as defined in the microcontroller as following defined formula
Percentage Weight Reduction (PWR) = 100*(abs(a[0]-a[n-1])/a[n-1])
If Percentage weight reduction (PWR) comes out to be less than X% (wherein X% is defined in the microcontroller as an ideal appropriate moisture percentage suitable for a sample) then a defined variable count is incremented by one. The process is repeated until variable count value reaches Y (wherein Y corresponds to the number of iterations to be performed predefined in the microcontroller) which correspond PWR to be less than X% for more than Y counts. This condition is incorporated in the algorithm within microcontroller to avoid any false detection of completion of drying. The microcontroller then accordingly turns off the heater element.
The same is defined in the flow chart also as below:

(1) Sample placement and initial temperature adjustment of dryer compartment by microcontroller

(2) Weight calculation using load cell and data transfer to microcontroller

(3)Weight Percentage Reduction Calculation

Those skilled in the relevant art will appreciate the design of the invented dryer. Further modification can be done as modified load cell can be placed which can result in accurate data of moisture percentage.
The above are only embodiments of the present invention, not to limit the patent scope of the present invention, therefore, the use of all contents of the specification and drawings of the present invention is made equivalent structures or equivalent processes transform, or direct or indirect application in the other related technical fields, are included within the same reason patentable scope of the invention.

NOVELTY, INVENTIVE STEP AND INDUSTRIAL APPLICATION
NOVELTY
Novelty of the present invention lies in disclosing a food dryer programmed for drying multiple food and spices wherein the moisture content of the sample is being monitored as per the weight loss percentage of the sample to be dried. A weight transfer means connected with the tray of sample is used for transferring the weight of sample to a load cell. Said load cell is placed outside the drying compartment which reverts the sample weight to a microcontroller. Embedded microcontroller is preprogrammed to monitor the weight percentage reduction of the sample at a predefined interval and accordingly the microcontroller sets the drying compartment.
INVENTIVE STEP
The technical advancement of knowledge lies in disclosing a compact automatic food dryer programmed for multiple food items wherein the food items is placed within drying compartment over a sliding tray suspended with a mechanical weight transfer means connected to a load cell. A flexible diaphragm used between drying compartment and mechanical transfer means restricts the escaping of hot air from drying compartment. Measured weight is continuously transferred to the load cell which is placed outside the drying compartment which converts sample weight into appropriate analog voltage. The load cell communicating with a microcontroller chip embedded outside drying compartment keeps converting obtained analog voltage into 24 bit digital voltage and stored in FIFO register within microcontroller and at a predefined intervals a percentage weight loss is calculated from latest value and last value of FIFO register and compared with ideal percentage weight loss as defined in microcontroller. The whole process is repeated for predefined iterations. The microcontroller accordingly sets the heat intensity within drying compartment. As per initial temperature of compartment by sensor, duty cycle is varied by microcontroller. All these features make clear that inventors have put in intellectual effort and thus this automatic food dryer is inventive as compared to existing food dryers of similar type.
INDUSTRIAL APPLICATION
The present invention has application in various food drying applications including various spices where maintaining temperature is crucial as far as moisture content is concerned. Being lightweight the invented dryer is easily portable. Hence finds a huge application in food drying equipment industry.

KOMPAL BANSAL (PA NO. 1754)
Dated: January 17, 2018 PATENT AGENT FOR THE APPLICANT