阅读说明：本技术 全自动连续膨化系统及控制方法 (Full-automatic continuous puffing system and control method ) 是由 高火星 郝育红 于 2020-11-23 设计创作，主要内容包括：本发明提供一种全自动连续膨化系统及控制方法,它包括依次连接的微波加热滚筒和电磁加热滚筒,微波加热滚筒位于上游；所述的微波加热滚筒内设有微波加热器,用于使玉米粒均匀加热；所述的电磁加热滚筒外壁设有电磁发生器,用于使玉米粒的外壁加热。使用时,将玉米粒在微波加热滚筒内加热到爆发前的临界状态；将玉米粒在电磁加热滚筒内加热到爆开成爆米花；将爆米花送入到筛筒内筛除碎屑和未爆开的玉米粒；将调味料粉喷吹在热的爆米花的表面；在爆米花跌落的过程中,以压缩空气将调味浆料喷吹到爆米花的表面。通过采用微波加热滚筒和电磁加热滚筒连续加热的方式,在实现全自动连续膨化的同时,并且能够获得更佳的口感。(The invention provides a full-automatic continuous puffing system and a control method, which comprises a microwave heating roller and an electromagnetic heating roller which are sequentially connected, wherein the microwave heating roller is positioned at the upstream; the microwave heating roller is internally provided with a microwave heater for uniformly heating the corn kernels; the outer wall of the electromagnetic heating roller is provided with an electromagnetic generator for heating the outer wall of the corn kernels. When in use, the corn kernels are heated in a microwave heating roller to a critical state before explosion; heating the corn kernels in an electromagnetic heating roller until the corn kernels are popped into popcorn; conveying the popcorn into a screen cylinder to screen out the chips and unpopped corn kernels; spraying the seasoning powder on the surface of the hot popcorn; during the fall of the popcorn, the seasoning paste is blown with compressed air onto the surface of the popcorn. By adopting the continuous heating mode of the microwave heating roller and the electromagnetic heating roller, the full-automatic continuous puffing is realized, and meanwhile, better mouthfeel can be obtained.)

1. A full-automatic continuous puffing system is characterized in that: the microwave heating device comprises a microwave heating roller (1) and an electromagnetic heating roller (2) which are sequentially connected, wherein the microwave heating roller (1) is positioned at the upstream;

a microwave heater (4) is arranged in the microwave heating roller (1) and is used for uniformly heating the corn kernels;

the outer wall of the electromagnetic heating roller (2) is provided with an electromagnetic generator (6) for heating the outer wall of the corn kernels.

2. The fully automatic continuous puffing system of claim 1, wherein: a plurality of radial support rods (108) are arranged in the microwave heating roller (1), the support rods (108) are connected with a rotating ring (107), and at least two groups of rotating rings (107) and support rods (108) are used for supporting the microwave heating roller body (105);

the rotating ring (107) is rotatably connected with the supporting shaft (102), and the supporting shaft (102) is connected with the supporting frame (103);

a first driving device (104) is also arranged for driving the microwave heating cylinder body (105) to rotate.

3. The fully automatic continuous puffing system according to claim 2, wherein: a microwave heater (4) is arranged at the position, close to the bottom, of the supporting shaft (102), and the microwave heater (4) is used for generating microwaves to heat corn kernels;

a plurality of first helical blades (101) are arranged on the inner wall of the microwave heating cylinder body (105) and used for pushing the corn kernels to move along the axial direction.

4. A fully automatic continuous puffing system according to claim 3, and further comprising: a temperature sensor (5) is also arranged on the microwave heating cylinder body (105);

for regulating the power of the microwave heater (4).

5. The fully automatic continuous puffing system of claim 1, wherein: the tail of the microwave heating roller (1) is provided with a transition slideway (12), the transition slideway (12) is an inclined slideway, one end of the transition slideway (12) is positioned on the outer wall of the tail end of the microwave heating roller body (105), and the other end of the transition slideway (12) is positioned in the electromagnetic heating roller body (204) of the electromagnetic heating roller (2).

6. The fully automatic continuous puffing system of claim 1, wherein: an electromagnetic heating cylinder body (204) of the electromagnetic heating roller (2) is supported by a rotating carrier roller (13) and is driven to rotate by a second driving device (202);

a plurality of second helical blades (201) are arranged on the inner wall of the electromagnetic heating cylinder body (204) and used for pushing the corn kernels or the popcorn to move along the axial direction.

7. The fully automatic continuous puffing system according to claim 6, wherein: the inner wall of the electromagnetic heating cylinder body (204) is also provided with an annular limiting ring (203), and the height of the limiting ring (203) is approximately the same as the thickness of the corn kernels and is used for blocking the corn kernels which are not popped.

8. A fully automatic continuous puffing system according to any of claims 6 or 7, characterized in that: a plurality of sound sensors (7) arranged along the axial direction are also arranged on the electromagnetic heating cylinder body (204) and used for determining the position of the popcorn.

9. The fully automatic continuous puffing system of claim 1, wherein: a screening drum (3) is arranged at the downstream of the electromagnetic heating roller (2) and is used for screening out scraps and unpopped corn kernels;

a powder blowing device (8) is arranged in the screen cylinder and is used for spraying powder in the powder cylinder (82) to the surface of the popcorn through a powder spray head (81) by compressed air;

and a guniting device (9) is further arranged at the downstream of the screen drum (3), and the guniting device (9) is used for blasting the slurry in the slurry barrel (95) to the surface of the popcorn through a blow pipe (93) by using compressed air in the process that the popcorn falls.

10. A method of using the fully automatic continuous puffing system according to any one of claims 1 to 9:

s1, heating the corn kernels in a microwave heating roller (1) to a critical state before explosion;

s2, heating the corn kernels in the electromagnetic heating roller (2) until the corn kernels are popped into popcorn;

a plurality of sound sensors (7) which are arranged along the axial direction are arranged in the electromagnetic heating roller (2) and are used for determining the position of the popcorn, and the power of the electromagnetic generator (6) and/or the rotating speed of the electromagnetic heating roller (204) are/is adjusted according to the position of the popcorn;

s3, conveying the popcorn into a screen cylinder (3) to screen out the scraps and unpopped corn kernels;

s4, spraying the seasoning powder on the surface of the hot popcorn;

s5, blowing the seasoning paste to the surface of the popcorn by using compressed air in the process of dropping the popcorn;

the continuous automatic production of the popcorn is realized through the steps.

Technical Field

The invention relates to microwave and electromagnetic puffed food processing equipment, in particular to a full-automatic continuous puffing system and a control method.

Background

Corn puffed foods, such as popcorn, are a favorite food product. The corn kernels are heated to 200-240 ℃ to be popped, so that the crisp taste is realized. Furthermore, various seasonings are added in the prior art, so that the taste of the popcorn is better.

A typical popcorn maker uses a pot-shaped configuration to fry the corn kernels with a flavoring until the corn kernels pop to form the popcorn. The problem of the scheme is that 1 is that the efficiency is lower, only intermittent production can be realized, the whole efficiency is lower, the difficulty of realizing automatic control is higher, and manual participation is required through feeding. 2, to wrap corn kernels and seasonings evenly, oil needs to be doped into the seasonings to ensure that the seasonings can flow, and more oil intake affects the health of people. 3, the flavor is influenced, the gasification temperature of part of flavor substances in the seasoning is lower than 200 ℃, and the heating temperature of the corn kernels is 200-240 ℃, so that a large amount of flavor substances are lost, and the taste is deteriorated. For example, the popcorn maker disclosed in patent document CN15100994A, the heating system of the electromagnetic popcorn device disclosed in CN 205727954U, and the electromagnetic popcorn device have such problems.

CN 107348361 a describes an automatic production equipment of popcorn, in which a feeder, a bulking machine, a lifting machine, a drying machine, a sieving machine, a sugar cooking mixer and a cooling conveyor are connected in sequence to form the automatic production equipment, so as to improve the processing efficiency. But wherein the specific construction of the bulking machine is not described in detail. The production line of the scheme is also long, and the scheme adds the seasonings into the syrup to produce products with different tastes, so that the influence on the flavor of the seasonings is large, and the flavor of the seasonings cannot be ensured. And the scheme still adopts a stirring and mixing scheme, and grease needs to be added.

Two ways of heating corn kernels are commonly used in the prior art, one being microwave heating, for example, CN1622764A describes a sweet and salty microwave popcorn composition and products containing these popcorn, and the microwave popcorn is shown in fig. 7 as microwave-heated corn kernels (25) and microwave-heated popcorn (26), which have a high degree of popping, very loose and unsightly shape, and readily absorb moisture. The popcorn is suitable for eating immediately after being popped, is not easy to preserve and has poor selling phase.

Another is an electromagnetic heating method, such as the fully automatic feeding electromagnetic popcorn machine described in CN 111642694 a, which can process popcorn that is nearly spherical and beautiful, but not as crisp as microwave-heated popcorn.

The description in the background art is only for describing the technology so as to facilitate understanding, and the content of the research on the corresponding technology by the inventor is included in the description, and is not in the prior art.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a full-automatic continuous puffing system and a control method, which can realize automatic continuous production, can obtain popcorn with better taste, and can keep the flavor of the final popcorn product as much as possible in an optimal scheme.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a full-automatic continuous puffing system comprises a microwave heating roller and an electromagnetic heating roller which are sequentially connected, wherein the microwave heating roller is positioned at the upstream;

the microwave heating roller is internally provided with a microwave heater for uniformly heating the corn kernels;

the outer wall of the electromagnetic heating roller is provided with an electromagnetic generator for heating the outer wall of the corn kernels.

In a preferred scheme, a plurality of radial support rods are arranged in the microwave heating roller and are connected with a rotating ring, and at least two groups of rotating rings and support rods are used for supporting the microwave heating roller body;

the rotating ring is rotatably connected with a supporting shaft, and the supporting shaft is connected with the supporting frame;

and a first driving device is also arranged for driving the microwave heating cylinder body to rotate.

In a preferred scheme, a microwave heater is arranged at a position, close to the bottom, of the supporting shaft and is used for generating microwaves to heat the corn kernels;

the inner wall of the microwave heating cylinder body is also provided with a plurality of first helical blades for pushing the corn kernels to move along the axial direction.

In a preferred scheme, a temperature sensor is also arranged on the microwave heating cylinder;

for regulating the power of the microwave heater.

In the preferred scheme, a transition slideway is arranged at the tail part of the microwave heating roller and is an inclined slideway, one end of the transition slideway is positioned on the outer wall of the tail end of the microwave heating roller body, and the other end of the transition slideway is positioned in the electromagnetic heating roller body of the electromagnetic heating roller body.

In a preferred scheme, an electromagnetic heating cylinder body of the electromagnetic heating cylinder is supported by a rotating carrier roller and is driven to rotate by a second driving device;

the inner wall of the electromagnetic heating cylinder body is provided with a plurality of second spiral blades for pushing corn kernels or popcorn to move along the axial direction;

in the preferred scheme, the inner wall of the electromagnetic heating cylinder body is also provided with an annular limiting ring, and the height of the limiting ring is approximately the same as the thickness of the corn kernels and is used for blocking the unpopped corn kernels.

In a preferred scheme, a plurality of sound sensors arranged along the axial direction are further arranged on the electromagnetic heating cylinder body and used for determining the position of the popcorn.

In a preferred scheme, a screening drum is arranged at the downstream of the electromagnetic heating roller and is used for screening out scraps and unpopped corn kernels;

a powder blowing device is arranged in the screen cylinder and used for spraying powder in the powder cylinder to the surface of the popcorn through a powder nozzle by compressed air;

and a guniting device is also arranged at the downstream of the screen cylinder and is used for blowing the slurry in the slurry barrel to the surface of the popcorn through a blow pipe by using compressed air in the process of dropping the popcorn.

A method adopting the full-automatic continuous puffing system comprises the following steps:

s1, heating the corn kernels in a microwave heating roller to a critical state before explosion;

s2, heating the corn kernels in an electromagnetic heating roller until the corn kernels are popped into popcorn;

a plurality of sound sensors which are arranged along the axial direction are arranged in the electromagnetic heating roller and are used for determining the position of the popcorn, and the power of the electromagnetic generator and/or the rotating speed of the electromagnetic heating roller body are/is adjusted according to the position of the popcorn;

s3, conveying the popcorn into a screen cylinder to screen out scraps and unpopped corn kernels;

s4, spraying the seasoning powder on the surface of the hot popcorn;

s5, blowing the seasoning paste to the surface of the popcorn by using compressed air in the process of dropping the popcorn;

the continuous automatic production of the popcorn is realized through the steps.

According to the full-automatic continuous puffing system and the control method, the full-automatic continuous puffing is realized and a better taste can be obtained at the same time by adopting a continuous heating mode of the microwave heating roller and the electromagnetic heating roller. In a preferred scheme, the powder and the slurry can be separated by adopting the structure of the powder blowing device and the slurry spraying device, so that more flavor substances are reserved, and better mouthfeel is further obtained.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

fig. 1 is a schematic view of the overall structure of the present invention.

FIG. 2 is a schematic cross-sectional view of a microwave heating roller according to the present invention.

Fig. 3 is a schematic structural view of the electromagnetic heating roller of the present invention.

Fig. 4 is a schematic sectional view a-a in fig. 3.

Fig. 5 is a schematic view of the arrangement structure of the guniting device in the invention.

Fig. 6 is a schematic structural view of a guniting device in the invention.

FIG. 7 is a schematic diagram of the process of the present invention in comparison to a prior art finished product.

Detailed Description

Example 1:

as shown in fig. 1, a full-automatic continuous puffing system comprises a microwave heating roller 1 and an electromagnetic heating roller 2 which are connected in sequence, wherein the microwave heating roller 1 is positioned at the upstream; the upstream and downstream in this example are based on the direction of movement of the corn kernels and popcorn. One end of the feeding is upstream, and one end of the discharging is downstream.

The microwave heating roller 1 is internally provided with a microwave heater 4 for uniformly heating the corn kernels;

the outer wall of the electromagnetic heating roller 2 is provided with an electromagnetic generator 6 for heating the outer wall of the corn kernels.

In a preferred embodiment, as shown in fig. 1, a feeding device is further provided, which comprises a feeding hopper 10 and a vibrating material distribution chute 11, so as to uniformly convey the corn kernels into a microwave heating cylinder 105 of the microwave heating roller 1. As shown in FIG. 7, the corn kernels 25 are usually heated by microwave, and the popped corn kernels are fully popped but easily broken due to the shape of the popped corn kernels 26 heated by microwave, and the structure has strong water absorption and is not easy to store, and the seasoning is mainly wrapped on the shells of the corn kernels and is lost more. While the corn kernels 23 are heated electromagnetically, the popped configuration, such as the shape of the electromagnetically heated popcorn 24, is approximately spherical, but the taste of the popcorn is not as crisp as the microwave heated popcorn. According to the analysis of the inventor, the corn kernels are not heated sufficiently probably by adopting electromagnetic heating, and the temperature gradient exists in the inner parts of the corn kernels, so that the inner parts are not puffed as much as the outer parts. By adopting the structure of the invention, the popping shape of the microwave and electromagnetic heating corn kernels 21 is close to spherical, the taste is more crisp, and the average circumcircle diameter of the shape of the statistical result is larger than that of the electromagnetically heated popcorn 24. The inventor probably analyzes that the structure of the invention can fully heat the inner part of the corn kernels, accumulate enough endogenous pressure, and the heating of the electromagnetic heating roller 2 can fully heat the outer shells of the corn kernels, so that the corn kernels are convenient to pop. Thus, the microwave and electromagnetic heating popcorn 22 can be obtained in a nearly spherical shape and with a more crispy texture. And adopt the structure of cylinder processing, be convenient for realize continuous processing, compare with the popped equipment of frying pan structure, production efficiency is higher.

Preferably, as shown in fig. 2, a plurality of radial support rods 108 are arranged in the microwave heating roller 1, the support rods 108 are connected with a rotating ring 107, and at least two groups of the rotating ring 107 and the support rods 108 are used for supporting the microwave heating roller 105; with this structure, the rotation of the microwave heating cylinder 105 is facilitated.

The rotating ring 107 is rotatably connected with the supporting shaft 102, and the supporting shaft 102 is connected with the supporting frame 103;

a first drive means 104 is also provided for driving rotation of the microwave heating cylinder 105. The outer wall of the microwave heating cylinder 105 is provided with a gear ring 106, the first driving device 104 is provided with a gear, the gear is meshed with the gear ring 106, and the variable frequency motor drives the gear to rotate through a speed reducer.

Preferably, as shown in fig. 2, a microwave heater 4 is arranged at a position of the supporting shaft 102 near the bottom, and the microwave heater 4 is used for generating microwave to heat the corn kernels; the microwave heaters 4 are arranged in a long strip shape, 3 in this example, and are installed at a position near the bottom of the supporting shaft 102. The heating temperature in the microwave heating roller 1 is controlled to be 180-200 ℃, so that the corn kernels are not exploded in the microwave heating roller body 105 as much as possible.

A plurality of first helical blades 101 are further arranged on the inner wall of the microwave heating cylinder 105 and used for pushing the corn kernels to move along the axial direction. At least one helical blade 101 passes axially through the space between the support rods 108.

In a preferred embodiment, as shown in fig. 1, a temperature sensor 5 is further provided in the microwave heating cylinder 105; the temperature sensor is preferably arranged in the microwave heating cylinder 105, and can also be arranged on the outer wall of the microwave heating cylinder 105, the heating temperature is obtained by indirect measurement, and the output power of the microwave heater 4 is dynamically adjusted according to the detected temperature.

In a preferred embodiment, as shown in fig. 1, a transition slideway 12 is provided at the tail of the microwave heating roller 1, the transition slideway 12 is an inclined slideway, one end of the transition slideway 12 is located on the outer wall of the tail end of the microwave heating roller 105, and the other end of the transition slideway 12 is located inside the electromagnetic heating roller 204 of the electromagnetic heating roller 2. By the structure, the conveying distance can be reduced, the temperature reduction of the corn kernels is further reduced, the energy consumption is saved, and the quality of finished products is ensured.

In a preferred scheme, as shown in fig. 3 and 4, the electromagnetic heating cylinder body 204 of the electromagnetic heating cylinder 2 is supported by the rotating carrier roller 13 and is driven to rotate by the second driving device 202; preferably, the barrel 204 is tapered, with the inlet diameter being smaller near the upstream and the diameter being larger downstream to allow sufficient space for the popcorn to be popped.

A plurality of second helical blades 201 are arranged on the inner wall of the electromagnetic heating cylinder 204 and used for pushing the corn kernels or the popcorn to move along the axial direction;

in a preferred scheme, as shown in fig. 3 and 4, an annular limiting ring 203 is further arranged on the inner wall of the electromagnetic heating cylinder 204, and the height of the limiting ring 203 is approximately the same as the thickness of the corn kernels, so that the limiting ring is used for blocking the unpopped corn kernels. With the structure, the quantity of unpopped corn kernels is greatly reduced.

In a preferred embodiment, as shown in fig. 3, a plurality of sound sensors 7 are arranged in the axial direction in the electromagnetic heating cylinder 204, and the sound quantity of the popcorn popping is collected to determine the popcorn popping position. With this structure, the popcorn is basically concentrated on the front section of the electromagnetic heating cylinder 204 for popping, and the rear section is mainly used for further drying the popcorn to reduce the moisture content. The explosion and the drying are completed by one electromagnetic heating roller 2, so that the temperature loss caused by the transfer of a hoister or other conveying equipment is reduced, the energy consumption is reduced, and the length and the occupied space of the whole production line can be shortened.

In a preferred scheme, as shown in figure 1, a sieve drum 3 is arranged at the downstream of the electromagnetic heating roller 2 and is used for sieving and removing the chippings and unpopped corn kernels; a discard chute 16 is arranged below the screen drum 3 and is used for collecting scraps and unpopped corn kernels. A waste conveying belt 15 is arranged below the waste slide way 16. In the embodiment, the structure of the screen drum 3 is adopted, the screen holes on the outer wall of the rotating screen drum are used for filtering, and excessively puffed popcorn is conveniently scattered in the rotating process, so that a finished product close to a spherical shape is kept as much as possible, and the overall appearance effect of the finished product is improved. It is of course also possible to replace the screen cylinder 3 with a flat vibrating screen.

Example 2:

on the basis of the embodiment 1, a further preferable scheme is that in fig. 1, a powder blowing device 8 is arranged in the screen cylinder and used for spraying powder in a powder cylinder 82 to the surface of the popcorn in a siphoning manner through a powder spray head 81 by using compressed air; so as to retain the flavor substances in the powder. Avoid the loss of flavor substances after being mixed with syrup. The compressed air is heated to 60-85 ℃, loss of flavor substances in the powder can be reduced, the powder can be further dried, and the powder is combined with water vapor on the surface of the popcorn, so that the popcorn can be conveniently coated on the surface of the popcorn. Preferably, the powder material comprises milk powder, powdered sugar, cocoa powder, vegetable powder, spice powder and the like.

Further preferably, as shown in fig. 1, 5 and 6, a guniting device 9 is arranged at the downstream of the screen cylinder 3, and the guniting device 9 is used for blowing the slurry in the slurry barrel 95 to the surface of the popcorn by compressed air through the blow pipe 93 during the dropping process of the popcorn. The slurry comprises sugar, grease, salt and other raw materials. In the scheme of the embodiment, the use amount of the grease can be greatly reduced due to the adoption of the slurry spraying process. In a preferred embodiment, the structure of the guniting device 9 is as follows: a pipeline of a compressed air source 91 passes through the hot blast stove 92 so as to heat compressed air to 100-200 ℃. The outer wall of the pulp barrel 95 is provided with a heating device 96 to maintain the temperature of the pulp barrel 95, preferably, the temperature of the pulp barrel 95 is 220-240 ℃, the siphon 98 is positioned in the pulp barrel 95, compressed air in the blowpipe 93 is blown through the upper end of the siphon 98 at a high speed, pulp is sprayed out by utilizing the siphon effect, the pulp is mainly syrup and is coated on the outer surface of the microwave and electromagnetic heating popcorn 22, and the pulp inlet pipe 97 is further arranged for continuously supplementing the pulp. Because the powder and the syrup are coated separately, a large amount of flavor substances are reserved, and the taste is improved. Compared with a frying pan processing mode, the scheme of the invention can also facilitate large-scale production and more facilitate automatic control.

Example 3:

on the basis of the embodiments 1 and 2, a control method adopting the full-automatic continuous puffing system comprises the following steps:

s1, heating the corn kernels in the microwave heating roller 1 to a critical state before explosion; the heating temperature is 185-200 ℃, and the heating time is less than or equal to 3 minutes.

S2, heating the corn kernels in the electromagnetic heating roller 2 until the corn kernels are popped into popcorn;

a temperature sensor is also arranged on the electromagnetic heating cylinder 204, and the heating temperature is 210-240 ℃. The heating time is less than or equal to 3 minutes. Preferably less than or equal to 2 minutes.

A plurality of sound sensors 7 which are arranged along the axial direction are arranged in the electromagnetic heating roller 2 and are used for determining the position of the popcorn, and the power of the electromagnetic generator 6 and/or the rotating speed of the electromagnetic heating roller 204 are/is adjusted according to the position of the popcorn; the corn kernels are forced to pop upstream of the electromagnetic heating cylinder 204 to allow sufficient drying time downstream.

S3, conveying the popcorn into a screen cylinder 3 to screen out the scraps and unpopped corn kernels;

s4, spraying the seasoning powder on the surface of the hot popcorn; the temperature of the blown compressed air is 60-85 ℃. So as to retain the flavor substances of the powder.

S5, blowing the seasoning paste to the surface of the popcorn by using compressed air in the process of dropping the popcorn; as shown in fig. 5, preferably, multiple slurry blows can be achieved in a multi-drop manner. To achieve a higher coating effect. Preferably, the slurry comprises a grease, such as butter; syrups, such as corn or sucrose syrup, salt, and the like. The slurry can well protect the flavor substances of the powder after hardening, and the slurry is coated on the surface of the popcorn instead of the surface of the corn grains. The temperature of the blown compressed air is 60-85 ℃. Compared with the coating mode of stirring in a frying pan, the invention can obtain thinner and more uniform slurry coating. And the popcorn does not need to be heated again.

The continuous automatic production of the popcorn is realized through the steps, and the finished popcorn product with better taste and appearance is obtained.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.