Seed coating apparatus

A seed coating apparatus comprises a seed supplying unit, a coating unit, a hardening unit and a washing unit assembled in series. The coating unit is provided with an exchangeable nozzle block having the nozzles and with passages for respectively feeding the nozzles with gelling solution. All the passages are simultaneously blocked-and-resumed by two valves, which slidably cross the passages at upstream and downstream portions thereof. Each nozzle is supplied therein with a seed through a cylinder disposed at the center thereof and with gelling solution from the passage flowing toward the cylinder through discharge ports in opposite to each other. Holes of the nozzles for dropping the gel-coated seeds to the hardening unit are closed by a shutter after the gel-coated seeds are dropped therefrom.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a novel and improved apparatus for coating
 seeds with gel, particularly which can produce a plurality of gel-coated
 seeds simlutaneously.
 2. Related Art
 Japanese Laid Open Gazette No. Hei 9-149,711, for example, discloses a
 well-known conventional apparatus for coating small seeds with gelling
 solution mixed together with nutrition, medicine and the like, wherein
 seeds are sucked to a plurality of sucking chips respectively, carried to
 the above portion of processing nozzles by the movement of the sucking
 nozzles and released into the respective nozzles. Each of the nozzles is
 previously fed therein with gelling solution so as to form a gel-membrane
 therein for receiving the released seed, thereby coating the seed with the
 gelling solution. In the same apparatus, the gel-coated seeds are dropped
 into hardening solution in a tank so as to be conveyed therein by the
 movement of paddles while the gel-coat thereof being hardened, and then
 are dropped into water or other washing liquid in another tank so as to be
 conveyed therein by a screw-typed conveyor while the hardening solution
 stuck to the outer surface thereof being washed out.
 The above-said conventional seed coating apparatus with gel has included
 some problems as follows:
 The apparatus has been able to processes only small seeds. Large seeds have
 been processed by a different apparatus.
 The sucking chips have been moved by actuators consisting of a horizontally
 moving cylinder and a vertically moving cylinder, so that there has been
 such a fear that the seeds carried by the sucking chips fall down by an
 inertial force at the intermediate of its carriage course where the
 carrying direction is changed. Additionally, the seed carrying means
 having such cylinders is complicated.
 The flow of gelling solution fed into each nozzle has been substantially
 horizontally oneway, so that when it was excessively pressurized, there
 has been a fear of deviation of the gel-membrane from its determined
 portion by the pressure. It has also caused the deviation of the
 gel-coated seed dropped between the nozzle and the hardening unit from its
 determined arrival portion in the hardening unit, so that the dropped
 gel-coated seed has hit its soft gel-coat against the paddle. On seeding,
 the resultant unevenly gel-coated seeds are sent through a hose or a
 seeding machine while rubbing against one another, thereby causing the
 inner seeds to be removed from the gel-coats or to be injured.
 The conveyors of the hardening unit and the washing unit has been
 mechanically different from each other as the above mentioned, thereby
 expensively increasing the kinds of parts. Additionally, the paddle of the
 hardening unit has been made of a plate bored by a plurality of slits for
 allowance of the hardening solution to pass therethrough, which has been
 laterally united at the upper and lower ends thereof in perpendicular to
 its conveyance direction, thereby causing its resistance against the
 hardening solution so as to push out the hardening solution together with
 the gel-coated seeds through a seed discharge hole of the hardening unit.
 SUMMARY OF THE INVENTION
 Regarding to a seed coating apparatus including a seed stocker, a plurality
 of seed holders for catching seeds from the seed stocker respectively, a
 seed holder block integrally provided with the seed holders, a plurality
 of nozzles for seed coating as many as the seed holders, a nozzle block
 integrally provided with the nozzles, and a seed carrying means for moving
 the seed holder block between the seed stocker and the nozzle block so as
 to carry seeds caught on the seed holders to the nozzles respectively, the
 first object of the present invention is to enable the seed coating
 apparatus to process every sized seed whether it is extremely small or
 large, thereby reducing the tooling cost for production of coated seeds.
 For attainment of the first objection, the seed holder block can be
 replaced another seed holder block having different seed holders in
 correspondence to the size of seed to be held, the nozzle block can be
 replaced with another nozzle block having different nozzles in
 correspondence to the size of seeds to be coated, and the position of the
 seed carrying means can be changed so as to change the distance between
 the seed holders and the seed stocker.
 Due to the exchangeability of the seed holder block and the nozzle block,
 the apparatus can process any sized (either small or large) seed, so that
 it is unnecessary to provide individual apparatuses for small seeds and
 large seeds. Also, due to the adjustability of the position of the seed
 carrying means, the seeds on the seed stocker are prevented from crashing
 by the seed holders or missing to be caught by the same.
 The second object of the present invention regarding to a seed
 resuming-and-blocking of the downstream portions are simultaneously
 performed.
 Accordingly, it comes to be unnecessary to provide the passages with
 individual valves respectively, thereby simplifying the construction and
 control of valves for the feeding of gelling solution and reducing the
 cost thereof. The integral first and second valves slidably crossing all
 the passages have mechanical errors less than a ball-type valve, thereby
 being prevented from an escape of gelling solution and enabling a constant
 quantity of gelling solution to be discharged to each nozzle. Also, they
 make the gelling solution simultaneously flowing through all the passages
 constant in quantity and term, thereby producing constant sized gel-coated
 seeds.
 The fourth object of the present invention regarding to the seed coating
 apparatus including a plurality of nozzles supplied therein with seeds and
 gelling solution respectively for coating the seeds with the gelling
 solution, each of the nozzles being provided with a hole for dropping a
 seed coated with gelling solution, is to prevent the gelling solution in
 the nozzles from a splash of hardening liquid raised from a hardening unit
 disposed below the nozzles for hardening the gel-coats of seeds.
 For attainment of the fourth object, the holes of the nozzles for dropping
 the gel-coated seeds to the hardening solution tank are opened-and-closed
 by a shutter. The shutter closes all the holes of the nozzles as soon as
 the gel-coated seeds are dropped from the holes.
 The fifth object of the present invention regarding to the similar seed
 coating apparatus including the first and second valves and the shutter is
 to interlock the valves and shutter properly, thereby simplifying the
 control system of them and making it less expensive.
 For attainment of the fifth object, the first and second valves and coating
 apparatus including a seed stocker, a nozzle for coating a seed therein,
 and a seed carrying means for carrying seeds on the seed stocker to the
 nozzle, is to simplify the mechanism and control of the seed carrying
 means for cost reduction or compacting and to simplify the carriage course
 thereof for preventing the seeds carried by the moving seed carrying means
 from falling down when the seed carrying means changes its carriage
 direction.
 For attainment of the second object, the carrying means is directed
 vertically slantwise, so that the carriage distance is reduced and the
 change of carriage direction vanishes, thereby reducing the vibration
 generated on the moving seed carrying means.
 Regarding to a seed coating apparatus including a plurality of parallel
 nozzles supplied therein with seeds and gelling solution respectively for
 coating the seeds with the gelling solution, and a plurality of parallel
 passages for respectively feeding the nozzles with gelling solution, the
 third object of the present invention is to simplify the control mechanism
 for simultaneously feeding all the nozzles with the gelling solution and
 to even the feeding of gelling solution to all the nozzles for diminishing
 the qualitative variation of gel-coated seeds or reducing defective
 pieces.
 For attainment of the third object, a single elongated first valve axially
 slidably crosses upstream portions of all the passages so as to
 block-and-resume the upstream portions, a single second valve slidably
 crosses downstream portions of all the passages so as to resume-and-block
 the downstream portions, a plurality of plungers are disposed respectively
 in the passages between the first and second valves for pushing out the
 gelling solution to the nozzles, and the first and second valves are
 joined with each other so as to slide together, so that the
 blocking-and-resuming of the upstream portions and the the shutter are
 joined together, so that the blocking-and-resuming of the upstream
 portions, the resuming-and-blocking of the downstream portions and the
 opening-and-closing of the openings of the nozzles are simultaneously
 performed. Accordingly, only one power source is required to operate the
 valves and shutter.
 The sixth object of the present invention regarding to a seed coating
 apparatus including a nozzle supplied therein with a seed and gelling
 solution for coating the seed with the gelling solution, and a plunger for
 pushing out gelling solution to the nozzle, is to improve the control of
 feeding the nozzles with gelling solution so that a gel-membrane is formed
 in the nozzle with reliability before the supplying of seeds for making
 sure that the gel-membranes are expanded after the seeds being provided
 thereon so as to make gel-coated seeds and drop them with their own
 weight.
 For attainment of the sixth object, the plunger is actuated in several
 steps. At the first step, it is actuated a little so as to feed the nozzle
 with some gelling solution, thereby forming gel-membranes therein. In the
 further steps, the plunger feeds the nozzle with the more gelling
 solution, so as to increase the thickness of gel-membrane, and finally
 drop it with a seed by its own weight.
 The seventh object of the present invention regarding the same apparatus is
 to avoid the oneway feeding of gelling solution to the nozzle for making a
 properly formed gel-coated seed in the nozzle.
 For attainment of the seventh object, a cylindrical member is provided in
 the center of the nozzle for allowance of a seed to pass therethrough, and
 gel discharge ports for discharging gelling solution to the nozzle are
 disposed in opposite to each other with respect to an axis of said
 cylindrical member. Accordingly, the flows of gelling solution discharged
 from the gel discharge ports to the nozzle counteract each other. Hence,
 the cylindrical member is not eccentrically pressed by a flow of gelling
 solution, so that the seed through the cylindrical member can be received
 by the gel-membrane at its predetermined position. Also, the gel-membrane
 can be made even in thickness and the gel-coated seed can be properly
 dropped from the nozzle to the predetermined portion in the hardening
 unit, thereby improving the reliability of nice products.
 The eighth object of the present invention, regarding to a seed coating
 apparatus including a hardening unit for hardening a gel-coat of a seed
 and a washing unit for washing out hardening liquid stuck to a surface of
 a gel-coat of a seed, is to diminish the resistance of seed pushing
 members of conveyors of the hardening and washing units against the
 liquids, for preventing the liquids from being pushed out together with
 the discharged gel-coated seeds.
 For attainment of the eighth object, a plurality of parallel pushing
 members in comb-like shapes consisting of a frame and teeth projecting
 from the frame are moved by each of the conveyors for pushing a seed
 coated with gel in either hardening liquid or washing liquid. The frame is
 substantially as long as the inner width of the tank and is directed in
 perpendicular to the conveyance direction of the conveyor.
 Moreover, for providing the hardening and washing units with common parts,
 the same tank and conveyor are provided for both the units.
 The ninth object of the present invention is to improve the above
 constructed hardening unit so as to be surely supplied at the
 predetermined portion thereof with the gel-coated seeds dropped from the
 nozzles without hitting the seed pushing members.
 For attainment of the ninth object, the conveyor of the hardening unit is
 intermittently driven so that a seed coated with gel is supplied into a
 space between the seed pushing members at the interval of the conveyor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 At first, general explanation will be given on an entire construction of a
 seed coating apparatus with gel of the present invention according to
 FIGS. 1, 2 and 3.
 The seed coating apparatus consists of a seed supplying unit 1, a coating
 unit 2, a hardening unit 3 and a washing unit 4, all of which are
 supported by a cabinet 10 having casters 12.
 The seed supplying unit 1 has a hopper 13, sucking chips (seed holders) 16
 and a seed carrying means 17 for moving the sucking chips 16. The coating
 unit 2 located above the center of the cabinet 10 receives seeds 5 (shown
 in FIG. 14) from the seed supplying unit 1, coats seeds 5 with gelling
 solution 6 (shown in FIG. 14) so as to swell them to the predetermined
 size, and drop them.
 The hardening unit 3 includes a liquid tank 19, which is filled with
 hardening liquid, extended rightwardly from the place just under nozzles
 60 (shown in FIG. 7 or others) of the coating unit 2. The tank 19 is
 provided at the right end thereof (laterally opposite to the nozzles 60 of
 coating unit 2) with a seed discharge hole 20. Conveyor belts 21 are
 parallely disposed front and rear in the tank 19 and are provided on their
 outer surfaces with a plurality of regularly spaced paddles (seed pushing
 members) 22 projecting in perpendicular to the conveying direction of the
 conveyor belts 21. The conveyor belts 21 are driven by a motor 26.
 Soft gel-coated seeds 7 (shown in FIGS. 11 and 14) are dropped from the
 coating unit 2 into the tank 19 to be sunk in the hardening liquid
 therein. The gel-coated seeds 7 are conveyed in the tank 19 by the rotary
 driving of the conveyor belts 21 having the paddles 22, while the
 gel-coats 6b (shown in FIG. 14) of the gel-coasted seeds 7 being hardened
 by the hardening liquid, and finally discharged through the seed discharge
 hole 20 to the washing unit 4. The span of time for hardening can be
 changed by the change of rotary speed of the motor 26, thereby enabling
 the degree of hardness of the gel-coats 6b of the gel-coated seeds 7 to be
 adjusted.
 The washing unit 4 is located substantially at the center of the cabinet
 10, and extended leftwardly from the place just under the seed discharge
 hole 20 of the hardening unit 3. Similarly to the hardening unit 3, the
 washing unit 4 is provided with the liquid tank 19, the seed discharge
 hole 20, the conveyor belts 21, the paddles 22, the motor 26, and other
 common parts, so that a unit serving as the hardening unit 3 can also be
 used as the washing unit 4.
 The gel-coated seeds 7 dropped from the seed discharge hole 20 of the
 hardening unit 3 through a guide tube 30 fall into a right end portion of
 the tank 19 of the washing unit 4 so as to be sunk in water (or other
 washing liquid) therein. While the gel-coated seeds 7 are conveyed in the
 tank 19 by the paddles 22 of the conveyor belts 21 driven by the motor 26,
 the water washes out the hardening liquid stuck to the surfaces of the
 gel-coats 6b of the gel-coated seeds 7, thereby stopping the advancing of
 hardening of the gel-coats 6b.
 A product container 24 is disposed below the washing unit 4 so as to
 receive the gel-coated seeds 7 as finally products dropped from the seed
 discharge hole 20 of the washing unit 4.
 Detailed explanation will be given on each of the seed supplying unit 1,
 coating unit 2, the hardening unit 3 and the washing unit 4.
 Referring to the seed supplying unit 1 shown in FIGS. 4 through 6, a seed
 stocker 31 is disposed leftwardly downward from the seed carrying means
 17, so that the seeds 5 from the hopper 13 are stored to some quantity on
 the stocker 31 so as to be easily sucked one by one onto the respective
 sucking chips 16 of the seed carrying means 17. In this regard, a frame 32
 is fixed on the top of the cabinet 10. A support base 33 is fastened onto
 the frame 32 through bolts and nuts so as to be adjustable in height. A
 vibrating plate 36 is disposed above the support base 33. A vibrator 34,
 which is electric-powered, for example, is fixed at the bottom thereof
 onto the support base 33 and an upwardly projecting vibrating member of
 the vibrator 34 is fixed to the vibrating plate 36. Rubber isolators 35
 are interposed between the support base 34 and the vibrating plate 36. A
 downwardly recessed portion 36a formed by the right portion of the
 vibrating plate 36 faces a downwardly extending discharge opening 13a of
 the hopper 13.
 The seeds 5 in the hopper 13 fall through the discharge opening 13a into
 the recessed portion 36a of the vibrating plate 36. The vibration of the
 vibrating plate 36 by the driving of the vibrator 34 makes the seeds 5 in
 the recessed portion 36a float and apart, so that the seeds 5 can be
 easily sucked onto the sucking chips 16.
 Regarding to the seed carrying means 17, a pair of upwardly rightward
 extending plates 40 are erected front and rear in parallel on the support
 base 33. A pair of support frames 41 are longitudinally interposed left
 and right in parallel between the tops of the front and rear plates 40. A
 stay 41a is mounted on the longitudinal center of each support frame 41. A
 pair of guide rods 43 slidably passing through a sucking chip moving
 cylinder 42 are fixedly interposed rightwardly upward slantwise in
 parallel between both the stays 41a. The cylinder 42 has a piston rod 42a
 parallely extending between the guide rods 43, which is fixed either or
 both of the stays 41a. A bracket 44, which is a plate bent in
 an.OMEGA.-like shape when viewed in side, is fixed at the longitudinal
 center thereof to the upper surface of the cylinder 42.
 A sensor mounting plate 47 is fixedly interposed between the front surfaces
 of the stays 41a. It may also be interposed between the rear surfaces of
 the stays 41a. On the top surface of sensor mounting plate 47, a position
 sensor 48 is mounted on the lower left portion thereof, and a position
 sensor 49 on the upper right portion thereof, so that the position sensors
 48 and 49 made of proximity switches detect the respective lowest and
 highest positions of slanting movement of the cylinder 42 or the sucking
 chips 16. As a result, the seed carrying means 17 of the present invention
 is provided with only the cylinder 42 serving as an actuator for carrying
 seeds, which moves vertically slantwise.
 A sucking chip block (seed holder block) 46 is disposed under the bracket
 44. A height adjusting bolt 45 is downwardly inserted through a hole bored
 through each of front and rear edges 44a of the bracket 44 and is screwed
 into each of front and rear female screws bored in the sucking chip block
 46. The bolt 45 is fastened to each of the edges 44a by a nut. The height
 of the sucking chip block 46 in relation to the bracket 44 can be adjusted
 by rotating operation of the bolts 45.
 The sucking chip block 46 is integrally provided with a plurality of
 downwardly projecting sucking chips 16 having regular intervals in a
 longitudinal row. The number of sucking chips 16 to be provided on the
 sucking chop block 46 is not limited. According to this embodiment, eight
 sucking chips 16 are provided in correspondence to the number of the
 nozzles 60 of the coating unit 2. The sucking chip block 46 is connected
 to a vacuum pump (not shown) through a hose for the evacuation of the
 interior of the carrier block 46, thereby enabling the seeds 5 stored in
 the recessed portion 36a of the vibrating plate 36 to be sucked onto lower
 end openings of the sucking chips 16 respectively.
 The sucking chip block 46 having the sucking chips 16 can be replaced with
 another sucking chip block 46 having different sized or shaped sucking
 chips 16 so as to fit seeds 5 in size or shape. As a result, the seed
 coating apparatus using the same seed supply unit 1 except the sucking
 chip block 46 can be fitted to various seeds in size, whether they are
 minute or large.
 If the distance between the lower ends of the sucking chips 16 and the
 upper surface of the recessed portion 36a were too short, the lower ends
 of the sucking chips 16 would crush the seeds 5 on the recessed portion
 36a. If the distance were too long, the lower ends of the sucking chips 16
 would come apart from the top surface of seeds 5 in the recessed portion
 36a, so that the seeds 5 could not be sucked thereto. Then, on every
 exchanging of the sucking chip block 46, or on every exchanging of seeds
 to be processed between different sized types while using the same sucking
 chip block 46, the bolts 45 are rotated for adjusting the height of the
 sucking chip block 46, so that the above said distance becomes just right
 for the seeds 5 to be sucked.
 Additionally, a thrust pin is reciprocally contained in each of the sucking
 chips 16 so that it projects outwardly from the lower end opening of the
 sucking chips 16 on the releasing of the seed 5 to the nozzle 60 of the
 coating unit 2.
 Referring to a series of process by the seed carrying means 17 in the seed
 supplying unit 1, firstly, the sucking chips 16 of the sucking chip block
 46 are located above the recessed portion 36a by the motion of the
 cylinder 42 and the detecting of the position sensor 49. The vacuum pump
 evacuates the interior of the sucking chip block 46 so that the seeds 5
 are stuck to the lower ends of the sucking chips 16 respectively. Then,
 the cylinder 42 is actuated so as to move the sucking chip block 46
 upwardly slantwise. When the sucking chip block 46 reaches the upper end
 of its movement, the position sensor 48 detects it, thereby stopping the
 cylinder 42. Finally, the evacuation by the vacuum pump is stopped and the
 thrust pins are extended outwardly from the respective sucking chips 16,
 thereby forcibly releasing the stuck seeds 5 into the respective nozzles
 60 of the coating unit 2. Then, the seed carrying means 17 repeats the
 same process.
 The conventional seed supplying unit has used a combination of a
 vertically-motive actuator and a horizontally-motive actuator for carrying
 the sucking chips, thereby being expensive and complicated. Furthermore,
 the long carriage distance and the intermediate change of carriage
 direction has caused high possibility of falling down of the seeds on the
 moving sucking chips. The seed carrying means 17 of the present invention
 has only the cylinder 42 for carrying the sucking chips 16, thereby
 reducing the number and cost of parts. The cylinder 42 moves straightly
 vertically slantwise so as to shorten the carriage distance thereof and
 dismiss the shocking change of carriage direction, thereby enabling the
 seeds 5 to be carried smoothly without falling down on the way.
 Additionally, the shape of the vibrating plate 36 and the position of a
 nozzle block 58 having the nozzles 60 are improved considering the slant
 moving direction of the sucking chips 16.
 Next, explanation will be given on the coating unit 2 according to FIGS. 1,
 7 through 10. As shown in FIG. 1, a base plate 53 is longitudinally spread
 between the tops of mounting plates 51 erected on the lateral centers of
 the front and rear sides of the cabinet 10. As shown in FIGS. 7, 8 and 9,
 on the base plate 53 is fixedly disposed a longitudinally elongated valve
 casing 54, a valve cylinder 55 and a plurality of thrust cylinders 56. The
 valve cylinder 55 with a piston rod 55a, which is longitudinally
 extensible toward the valve casing 54, is disposed in front of the valve
 casing 54. The thrust cylinders 56 with piston rods 56a, which is
 laterally extensible toward the valve casing 54, are longitudinally
 juxtaposed at the right of the valve casing 54. The valve cylinder 55 and
 the thrust cylinder 56 (consisting of a first cylinder 56b and a second
 cylinder 56c as discussed below) are pneumatic, electromagnetic, hydraulic
 or so on. On the left side of the valve casing 54 is fixed a nozzle block
 58 forming a plurality of vertical processing nozzles 60 in a longitudinal
 row. According to this embodiment, the coating unit 2 is provided with
 eight thrust cylinders 56 and eight processing nozzles 60, both which are
 as many as the sucking chips 16, so as to coat eight seeds with gel
 simultaneously. The number of cylinders 56 and nozzles 60 can be changed
 according to the number of the sucking chips 16.
 Both of elongated first valve 61 and second valve 62 in rod-like shapes
 pass axially slidably and longitudinally through the valve casing 54. A
 shutter 63 in a horizontal plate-like shape is disposed below the nozzle
 block 58. The front ends of the first and second valves 61 and 62 and the
 shutter 63 are fixed onto a connecting member 64 fixed to the piston rod
 55a of the valve cylinder 55, so that they are integrally moved
 longitudinally by the action of the piston rod 55a of the valve cylinder
 55, thereby simultaneously operating the opening-and-closing of valve
 holes 61a and 62a (discussed below) of the first and second valves 61 and
 62 and openings 63a (discussed below) of the shutter 63.
 A longitudinally long hole 53a is bored vertically through the base plate
 53. A longitudinally long gel supplying casing 57 is fixedly hung from the
 lower surface of the valve casing 54 through the hole 53a. In the gel
 supplying casing 57 is bored a gel supplying hole 57a in a longitudinal
 direction, whose rear end opening is connected to an outer gel (coating
 solution) supplying tank (not shown) through a hose or the like, and are
 bored a plurality of top-opening gel dividing holes 57b vertically
 branching from the gel supplying hole 57a at regular intervals.
 As shown in FIGS. 6, 7 and others, in the valve casing 54 are bored a
 plurality of bottom-open vertical first gel passages 54a in a longitudinal
 row, so as to join the bottom-opening thereof with the top-opening of the
 gel-dividing holes 57b respectively. In the same are bored a plurality of
 laterally throughout second gel passages 54b in a longitudinal row. The
 top ends of the first gel passages 54a join the intermediate portions of
 the second gel passages 54b respectively. The left openings of the second
 gel passages 54b are respectively connected to the nozzles 60 of the
 nozzle block 58 as discussed below. Each of the second gel passage 54b
 forms at the right side portion thereof a diametrically large plunger
 chamber 54c which is outwardly open toward the piston rod 56a of the
 thrust cylinder 56. The first valve 61 crosses the intermediate portions
 of all the first gel passages 54a and the second valve 62 crosses the
 intermediate portions of all the second gel passages 54b between their
 joint portions with the first gel passages 54a and their left ends (toward
 the nozzles 60). The first valve 61 is bored through by a plurality of
 vertically diametric valve holes 61a in correspondence to the first gel
 passages 54a. The second valve 62 is bored through by a plurality of
 laterally diametric valve holes 62a in correspondence to the second gel
 passages 54b. The shutter 63 is bored by vertically throughout openings
 63a located in relation to gel-membrane holes 71c (discussed below) just
 under the nozzles 60, as shown in FIG. 7.
 The first and second valves 61 and 62 and the shutter 63, which are
 connected to the connecting member 64, are located so that the resumption
 of the second gel passages 54b through the valve holes 62a, the
 overlapping of the gel-membrane holes 71c with the openings 63a and the
 blocking of the first gel passages 54a by offsetting of the valve holes
 61a are performed simultaneously. This situation appears when the piston
 rod 55a of the valve cylinder 55 is positioned at its first operation
 position. When the piston rod 55a is at its second operation position, the
 first valve 61 resumes the first gel passages 54a through the valve holes
 61a and the valve holes 62a and the openings 63a are offset so as to shut
 the second gel passages 54b and the gel-membrane holes 71c,
 simultaneously.
 As shown in FIG. 9, the right portion of the plunger chamber 54c is
 female-screwed. A cylindrical adjusting bolt 66 having a male screw at its
 outer periphery and a flange at its outer end is screwed into the
 female-screwed portion of the plunger chamber 54c. In each of the plunger
 chambers 54c is disposed a laterally axial plunger 65, which is
 substantially diametrically as large as the second gel passage 54b, freely
 through the adjusting bolt 66. The inner (left) end portion of the plunger
 65 is slidably inserted into the second gel passage 54b. In the plunger
 chamber 54c, between the inner (left) end thereof and the inner (left) end
 of the adjusting bolt 66 is interposed a compression spring 59, which
 absorbs a shock caused by the abutting of a stopper 67 discussed below
 against the adjusting bolt 66.
 The stopper 67 engages peripherally with a screwed portion 65a co-axially
 projecting from the outer (right) end of the plunger 65, thereby being
 able to abut against the flange-like outer end of the adjusting bolt 66.
 At the outside of the stopper 67, the screwed portion 65b is screwed into
 the utmost end of the piston rod 56a of each thrust cylinder 56.
 Accordingly, the plunger 65 and the stopper 67 are operated integrally
 with the piston rod 56a. The position where the stopper 67 abuts against
 the adjusting bolt 66 defines the most extension position of the piston
 rod 56a, which can be adjusted by the rotation of the adjusting bolt 66
 for locating its flange, thereby adjusting the stroke of the plunger, that
 is, the position of the most-advanced inner end of the same defining the
 amount of discharge of the gelling solution 6. Even if the most-advanced
 inner end of the plunger 65 is adjusted the most leftwardly (toward the
 nozzle block 58), it is remains rightward (toward the thrust piston 56)
 from the joint position of the first and second gel passages 54a and 54b.
 The thrust cylinder 56 is so constructed that the piston rod 56a thereof is
 advanced in several steps. According to this embodiment, as shown in FIG.
 9, the thrust cylinder 56 consists of a pair of a first cylinder 56b and a
 second cylinder 56c in tandem connection, thereby making the piston rod
 56a extensible in two steps. At the first step, the first cylinder 56b is
 actuated so as to advance the piston rod 56a together with a piston (not
 shown) of the first cylinder 56b. At the second step, the second cylinder
 56c is actuated so as to advance the piston rod 56a apart from the first
 cylinder 56b. The stroke of the first cylinder 56b can be adjusted by
 rotation of an adjusting bolt 68 attached onto the outer (right) end of
 the first cylinder 56b.
 Explanation will be given on the control of the first and second valves 61
 and 62 and the shutter 63 by the valve cylinder 55 and the control of the
 plungers 65 by the thrust cylinder 56 in one process of feeding the
 nozzles 60 with the gelling solution 6. At first, in the condition that
 all the first and second gel passages 54a and 54b are wholly filled with
 gelling solution 6 from the gel supplying hole 57a, the piston rod 55a of
 the valve cylinder 55 is located at the first operation position. Hence,
 the first valve 61, which slides so as to offset the valve holes 61a from
 the first gel passages 54a, blocks all the first gel passages 54a, thereby
 preventing the gelling solution 6 from being introduced into the gel
 supplying casing 57 by the afterward advancing of the plungers 65.
 Simultaneously, the second valve 62 resumes all the second gel passages
 54b through the valve holes 62a thereof. The openings 63a of the shutter
 63 are located just under the gel-membrane holes 71c of the nozzles 60
 respectively.
 In this situation, all the thrust cylinders 56 are actuated simultaneously
 so as to advance the plungers 65, thereby discharging the gelling solution
 6 within the second gel passages 54b into the nozzles 60 respectively. In
 this regard, at the first operation step of each of the thrust cylinders
 56, each of the first cylinder 56b is actuated so as to advance the
 plunger 65 (leftwardly) a little, thereby pushing out a little gelling
 solution 6 into the gel-membrane hole 60c at the lower portion of the
 nozzle 60. As a result, the gelling solution 6 filled in each of the
 gel-membranes holes 71c becomes a gel-membrane 6a. Then, the seed 5 is
 released from each of the sucking chips 16 located over the nozzles 60,
 and is caught on the gel-membrane 6a. Next, at the second step of the
 thrust cylinder 56, the second cylinder 56c is actuated so as to further
 advance the plunger 65, thereby expanding the gel-membrane 6b retaining
 the seed 5 in the nozzle 60 (in the gel-membrane hole 60c). When the
 thickness of the gel-membrane 6a becomes sufficiently large, the
 gel-coated seed 7 falls with its own weight from the gel-membrane hole 60c
 into the hardening unit 3 through the openings 63a of the shutter 63.
 Then, the piston rod 55a of the valve cylinder 55 is switched to the second
 operation position. Hence, the openings 63a of the shutter 63 is offset
 from the gel-membrane hole 60c, thereby preventing the gelling solution 6
 from escaping from the gel-membrane hole 60c. The second valve 62 blocks
 all the second gel passages 54b, thereby preventing the gelling solution 6
 from being discharged to the nozzles 60. The first valve 61 resumes the
 first gel passage 54a through the valve hole 61a, so as to introduce the
 gelling solution 6 from the gel supplying hole 57a into the second gel
 passage 54b before the second valve 62 through the first gel passages 54a,
 thereby making preparations for the next discharge of the gelling solution
 6 to the nozzles 60.
 Next, referring to the nozzle block 58 of the coating unit 2 as shown in
 FIGS. 9 and 10, it is assembled from an upper casing 70 and a lower casing
 71, both of which are fixed onto the left side surface of the valve casing
 54 facing the seed supplying unit 1, and nozzle pipes 72 as many as the
 sucking chips 16. The interior of each nozzle pipe 72 defines a seed
 passing hole 60a of the nozzle 60. The upper and lower casings 70 and 71
 are bored respectively by vertical throughout holes 70a and 71a in a
 longitudinal row at regular intervals. Each hole 70a is joined with each
 hole 71a vertically sequentially when the upper and lower casings 70 and
 71 are joined with each other. The nozzle pipes 72 are inserted into the
 respective tandem holes of 70a and 71a. A flange portion 72a is formed by
 a vertical intermediate portion of each nozzle pipe 72. The outer surface
 of the upper half portion of the nozzle pipe 72 above the flange portion
 72a adheres closely to the wall of the hole 70a. The hole 71a is formed
 step-wise from a top-opening upper diametrically large portion and a
 bottom-opening lower diametrically small portion, which are vertically
 coaxially joined together. The lower half portion of the nozzle pipe 72
 below the flange portion 72a is disposed in the diametrically large
 portion of the hole 71a. The flange portion 72a is placed on the upper
 surface of the lower casing 71, in other words, the edge of the lower
 casing 71 around the top opening of the hole 71a, and is suppressed by the
 bottom of the upper casing 70.
 The diameter of the diametrically large portion of the hole 71a is larger
 than that of the outer periphery of the lower half portion of the nozzle
 pipe 72 therein, and the bottom thereof is disposed below the bottom of
 the nozzle pipe 72. The gap between the inner surface of the diametrically
 large portion of the hole 71a and the outer surface of the nozzle pipe 72
 defines a gel chamber 60b of the nozzle 60. The diametrically small
 portion of the hole 71a serving as a gel-membrane hole 60c is located just
 under the lower end of the nozzle pipe 72.
 Thus, the nozzle 60 is constituted by the nozzle pipe 72 having the seed
 passing hole 60a, the lower casing 71 having the gel chamber 60b and the
 gel-membrane hole 60c, and the like, so that the nozzles 60 as many as the
 sucking chips 16 of the seed supplying unit 1 are formed by the nozzle
 block 58. Similarly to the sucking chip block 46 of the seed supplying
 unit 1, the nozzle block 58 can be replaced with another having different
 nozzles 60, in correspondence to the size or shape of the seeds 5 to be
 processed.
 The lower casing 71 is provided therein with horizontal gel discharge
 passages 71b interposed between the second gel passages 54b and the gel
 chamber 60b respectively. The gel discharge passage 71b is connected at
 the entrance port thereof with the discharge opening (left) end of the
 second gel passage 54b, separates at the intermediate portion thereof into
 two longitudinally opposite directions and is connected with the gel
 chamber 60b through its exit ports 71c disposed oppositely to each other
 about the axis of the seed passing hole 60a or apart from each other at
 180 degrees. The two separations of the gel discharge passage 71b have the
 same lengths and the same diameters, thereby assuming the gelling solution
 6 to flow therethrough in the same quantity and the same pressure.
 The gelling solution 6 pushed out from the second gel passage 54b flows
 horizontally into the gel chamber 60b toward the outer surface of the
 nozzle pipe 72 through the pair of exit ports 71c in the same quantity and
 pressure. The both gel-flows from the exit ports 71c diminish each other
 in pressure and flow into the lower gel-membrane hole 60c. Accordingly,
 the nozzle pipe 72 is prevented from eccentrically offset caused by the
 pressure of gelling solution 6, thereby make sure of the seed 5 passing
 through the seed passing hole 60a properly. Also, the gelling solution 6
 evenly flows into the gel-membrane hole 60c, thereby enabling an even
 gel-membrane 6a to be formed therein. Moreover, the gel-coated seed 7 can
 be dropped properly vertically from the gel-membrane hole 60c through the
 opening 63a of the shutter 63, thereby enabling it to surely fall into the
 space between the paddles 22 in the hardening unit 3 just below the nozzle
 60.
 The process of seed coating in the nozzle 60 will be described in
 accordance with FIG. 14. Referring to FIG. 14(a), in the precondition that
 the whole of the gel discharge passage 71b and the gel chamber 60b is full
 of the gelling solution 6 and the gel-membrane hole 60c holds therein a
 gel-membrane 6a as a remaining part of the fed gelling solution 6, the
 piston rod 55a of the valve cylinder 55 is operated to the second
 operation position so as to block each of the first gel passages 54a by
 the first valve 61, resume each of the second gel passages 54b by the
 second valve 62 and locate the opening 63a of the shutter 63 just under
 the gel-membrane hole 60c. Then, the thrust cylinder 56 is operated at the
 first step so as to advance the plunger 65 a little, so that the thickness
 of gel-membrane 6a is increased as shown in FIG. 14(b), whereby the
 dropped seed 5 through the seed passing hole 60a can be caught on the
 gel-membrane 6a without the tear of the gel-membrane 6a causing only the
 seed 5 to fall into the hardening unit 3.
 Referring to FIG. 14(c), the plunger 65 is advanced to the maximum position
 at the second operation step of the thrust cylinder 56, so that the
 gelling solution 6 is further pushed out and the gel-membrane 6a swells to
 a certain thickness while involving the seed 5 and an air bubble. Finally,
 the weight of gel-membrane 6a can no longer support the weight of the seed
 5 and itself, so that the seed 5 with the gel-coat 6b as a gel-coated seed
 7 falls to the hardening unit 3 while the gel-coat 6b being ball-like
 shaped by its surface tension as shown in FIG. 14(c). After that, the
 piston rod 55a of the valve cylinder 55 is positioned at the first
 operation position, so that the first valve 61 slides to the closing
 position, the second valve 62 slides to the opening position and the
 shutter 63 closes the underbeneath of the gel-membrane hole 60c, and then,
 the thrust cylinder 56 is returned so as to back off the plunger 65,
 whereby the second gel passage 54b before the second valve 62 is fed with
 the gelling solution 6 through the first gel passage 54a, thereby making
 preparations for the next seed coating in the nozzle 60.
 In the nozzle block 58, such a series of process is repeated in each nozzle
 60 simultaneously, thereby enabling a large quantity of gel-coated seeds 7
 to be produced.
 Explanation will next be given on the hardening unit 3 in accordance with
 FIGS. 11, 12 and 13. A pair of front and rear plates 75 are parallely
 erected on the cabinet 10. The liquid tank 19 filled with hardening liquid
 is disposed in a lower half space between both of the plates 75. Above the
 tank 19 in the space between the plates 75 are parallely longitudinally
 disposed a driving shaft 76 at the right side end area thereof and a
 tension shaft 78 at the left side end area thereof. A driven shaft 77,
 which is longitudinally disposed leftwardly downward from the driving
 shaft 76 in the same space, is hooked on upper portions of the plates 75.
 The ends of the driving and driven shafts 76 and 77 are journalled by
 bearings fixed to the plates 75, and the ends of the tension shaft 78 are
 journalled by bearings laterally slidably supported by the plates 75.
 A front pulley 80 and a wide rear pulley 81 are fixed on the driving shaft
 76. A pair of pulleys 82 are fixed front and rear on the driven shaft 77.
 A pair of pulleys 83 are fixed front and rear on the tension shaft 78. The
 pair of conveyor belts 21 are tied around the front series of pulleys 80,
 82 and 83 and the rear series of pulleys 81, 82 and 83 respectively. The
 tension shaft 78 is laterally moved by rotation of a bolt 79, thereby
 adjusting the tension of conveyor belts 21. A mounting plate 86 is laid
 between the right upper portions of both plates 75. The motor 26 is
 mounted on the mounting plate 86. A belt 85 is interposed between the
 pulley 81 and a pulley 84 fixed on a driving shaft of the motor 26.
 A plurality of segments 90 are fixed at regular intervals on the outer
 surface of each conveyor belt 21. The conveyor belts 21 are located so
 that, when viewed in front, the segments 90 on the front conveyor belt 21
 exactly overlap with those of the rear conveyor belt 21. The paddle 22 is
 fixedly interposed between each pair of front and rear overlapping
 segments 90 on the front and rear belts 21. When the motor 26 is set off,
 the upper paddles 22 between the pulleys 80 and 81 and the pulleys 83
 vertically overlap with the lower paddles 22 between the pulleys 82 and
 the pulleys 83, and an interval between laterally adjacent upper paddles
 22 and an interval between laterally adjacent lower paddles 22 are located
 at the vertically downward position from the series of nozzles 60 of the
 nozzle block 58. The gel-coated seeds 7 dropped from the nozzles 60 as the
 arrow A in FIG. 11 pass through between the upper adjacent paddles 22 and
 reach the space between the lower adjacent paddles 22. When one dropping
 process of the gel-coated seeds 7 from the coating unit 2 is over, the
 motor 26 is switched on so as to drive the conveyor belts 21 to move as an
 arrow B in FIG. 11. Hence, the left paddle 22 of the adjacent left and
 right lower paddles 22 moves while pushing the gel-coated seeds 7 and
 finally is replaced with the next left paddle 22, then the motor 26 is
 switched off. In this state, the spaces between the next upper and lower
 paddles 22 are located just below the nozzles 60, thereby making
 preparations for the next dropping of the gel-coated seeds 7. During the
 repeat of such conveying process, the gel-coated seeds 7 are conveyed in
 the hardening liquid in the tank 19 until they reach the seed discharge
 hole 20, while the gel-coat 6b of the gel-coated seeds 7 being hardened.
 As shown in FIGS. 2 and 11, a sensor 94 for detecting the paddle 22 is
 disposed on the mounting plate 86 so as to control the driving of the
 conveyor belts 21. When a segment 94a projecting from the sensor 94 abuts
 against the moving paddle 22, the sensor 94 is switched so as to shut down
 the motor 26, whereby the conveyor belts 21 stop so that the spaces
 between the upper paddles 22 and between the lower paddles 22 are exactly
 located just below the nozzles 60. Then, the thrust cylinders 56 are
 operated at the second step so as to drop the gel-coated seeds 7 from the
 nozzles 60 into the tank 19 of the hardening unit 3. The motor 26 is not
 switched on until a predetermined time after the operation of the thrust
 cylinders 56, thereby synchronizing the dropping of the gel-coated seeds 7
 with the stopping of the conveyor belts 21. Thus, the motor 26 is
 intermittently driven. The hardening time can be adjusted for adjustment
 of the hardness degree of the gel-coat 6b of the gel-coated seed 7 by
 changing the start timing of the motor 26. In this regard, the motor 26
 may starts after two or more continuous dropping processes of the
 gel-coating seeds 7 from the nozzles 60.
 As shown in FIGS. 13(a) and 13(b), the paddle 22 is formed in a comb-like
 shape from a horizontally extending paddle frame 22a substantially as long
 as the inner width of the tank 19 and paddle teeth 22b vertically
 projecting from the paddle frame 22a at regular intervals. An interval
 between adjacent paddle teeth 22b is so narrow as not to allow the
 gel-coated seed 7 to pass therethrough. The front and rear portions of the
 paddle frame 22a are attached to the pair of segments 90 on the front and
 rear conveyor belts 21 respectively, whereby the paddle 22 is
 longitudinally disposed between the pair of front and rear segments 90.
 While the paddle teeth 22b or paddle frames 22a of the paddles 22 push the
 gel-coated seeds 7 during the driving of the conveyor belts 21, the
 hardening liquid in the tank 19 flows through the spaces between the
 paddle teeth 22b, thereby diminishing the resistance of the moving paddles
 22 against the hardening liquid.
 The convention paddle is made of a plate having a plurality slits for
 allowing the hardening liquid to pass therethrough, so that the utmost end
 of the paddle is horizontally united in perpendicular to the direction of
 conveyance, thereby being resistant against the hardening liquid. Such
 paddles have caused the hardening liquid to flow out together with the
 gel-coated seeds through a downstream seed discharge hole. When the
 comb-like paddle 22 of the present invention are used, the hardening
 liquid can flow through between separate utmost ends of the paddle teeth
 22b with a little resistance, thereby being prevented from being pushed
 out from the seed discharge hole.
 The right side end portion of the tank 19 having the bottom-open seed
 discharge hole 20 is extended outwardly from the right end of the front
 and rear plates 75. A bottom plate of the tank 19 partly forms an upward
 slope 19a along the locus of the utmost ends of the paddles 22 of the run
 of the conveyor belts 21 between the pulleys 83 and the pulleys 80 and 81.
 The top end of the slope 19a is located above the level surface of the
 hardening liquid and a vertical wall extends downwardly from the top end
 of the slope 19a so as to define the left wall of the seed discharge hole
 20.
 Each group of the gel-coated seeds 7 pushed by each paddle 22 ascend the
 upward slop 19a. On reaching the top of the slop 19a, the gel-coated seeds
 7 escape from the hardening liquid, and fall through the seed discharge
 hole 20 to the washing unit 4.
 Additionally, the tank 19 is provided at the center of the bottom thereof
 with a draining hole 91. It is also provided at an optional portion of the
 front surface thereof with a hardening liquid supplying hole 92 which is
 connected to a reservoir tank 93 disposed on the right upper portion of
 the cabinet 10 as shown in FIG. 1 through a hose (not shown) for supplying
 the tank 19 with the hardening liquid.
 As shown in FIG. 1, the washing unit 4 is the same however laterally
 reversed unit of the hardening unit 3. The tank 19 of the washing unit 4
 is full of water (or other washing liquid) instead of hardening liquid.
 The hardening and washing units 3 and 4 share components with each other,
 thereby reducing tooling cost. However, the motor 26 of the washing unit 4
 is not intermittently but continuously driven. For this reason, the
 gel-coated seeds 7 dropped from the hardening unit 3 have sufficiently
 hardened gel coats 6b which resist crushing by the paddles 22, and the
 continuous driving of the motor 26 enhances the washing efficiency.
 The guide tube 30 is hung from the bottom opening of the seed discharge
 hole 20 of the hardening unit 3 so as to locate the lower end thereof just
 above the upper ends of the upper paddles 22 at the right portion of the
 washing unit 4, thereby surely guiding the gel-coated seeds 7 into the
 water in the tank 19 of the washing unit 4 without escape. The gel-coated
 seeds 7 are conveyed in the tank 19 while the hardening liquid stuck to
 the gel-coats 6b thereof being washed out by the water therein. Similarly
 to the hardening unit 3, the gel-coated seeds 7 escapes from the water on
 the top of the slope 19a and fall through the seed discharge hole 20 into
 the product container 24 disposed below the washing unit 4.
 Regarding to both the hardening unit 3 and the washing unit 4, the
 comb-like paddles 22 are less resistant against the liquid than the
 conventional types, thereby preventing the liquid from being pushed out
 from the respective seed discharge holes. The seed supplying portions of
 both the units 3 and 4 are not provided laterally outwardly from the most
 outside paddles 22 but above the paddles 22, so that the units 3 and 4 can
 be laterally narrowed and the units 2, 3 and 4 can be arranged so as to
 entirely overlap when viewed in plan, thereby laterally compacting the
 seed coating apparatus.
 As shown in FIG. 1, on a left side portion of the cabinet 10 is disposed a
 controller box 11 containing a controller, which is electrically connected
 with the sensors (48, 49, 94 and the like) and the actuators (the
 cylinders 42, 55 and 56, the motors 26 and the like) of the units 1, 2, 3
 and 4 of the apparatus, thereby controlling the operational timing, time
 scale or the like of the actuators.