DEVICE FOR SOWING SEED BY SUCTION NOZZLE AND A SENSING DEVICE FOR DETECTING THE SEED

Abstract: The invention concerns a sowing device based on suction nozzles, said apparatus incorporating a sensor (12) for detecting the release of a seed from the nozzle at the sowing point. The invention is particularly suited to sowing seeds into a matrix of seedling containers.

Description: Device for sowing seed by suction nozzle and a sensing device for detecting the seed. The present invention relates to a device for sowing in which seeds are picked up by means of suction nozzles and dropped on a substrate. The invention is particularly suited to use for sowing seeds into a matrix of seedling containers. Sowing apparatuses equipped with suction nozzles are known in the art. They operate by using vacuum to pick up a seed from a tray onto a hole at the tip of a nozzle, after which the nozzle is taken to the sowing point and the seed is dropped onto the substrate. One such apparatus is known from, e.g., patent publication NO 119708. A problem of the above-described conventional sowing apparatuses is that if the nozzle hole fails to pick up a seed, the substrate remains unseeded at those points. This invention discloses a novel device characterized in claim 1 of the appended claims. Some of its preferred embodiments are disclosed in the dependent claims. The device comprises a sensor placed below the nozzle at the sowing point, capable of positively detecting the dropping of the seed onto the substrate. At a failure to drop a seed, said sowing point can be resown. Hence, unseeded points on the substrate are avoided. A few preferred embodiments of the invention are next examined in greater detail. In the appended drawings Fig. 1 shows the suction nozzle picking up a seed from the seed tray, Fig. 2 shows the seed container in greater detail * (from the opposite side) , and Fig. 3 shows the suction nozzle and the seed sensor at the sowing point. The sowing device has in a row a number of vertically aligned suction nozzles 1, whose lower end is provided with a hole 2 smaller than the seed. The nozzles are mounted in a frame 3 (Fig. 3) which also houses a vacuum system that provides the suction at the nozzle tips. Furthermore, the frame incorporates a vibrating arrangement which serves to detach any extra seeds which might adhere to the nozzle holes. Alternatively, the array of separate nozzles can be replaced by a rotating drum of nozzles. The seeds to be sown are placed on an elongated seed tray 4 aligned parallel with the row of the suction nozzles. The sowing is started by bringing the seed tray under the nozzles so that the tips of the nozzles can come in contact with the surface of the seed layer and then switching on the vacuum system to develop suction at the nozzle tips, whereby each nozzle tip picks up a seed. The amount of seeds in seed tray 4 is consistently kept at a relatively low level. This arrangement reduces the need for an excessive amount of seeds in the tray. The seed tray 4 is further connected to a larger feed bin 5 from which the tray can be replenished with seeds when necessary. Seed replenishment can be automated to take place at regular intervals, whereby the number of seeds and their level on the tray can be kept almost unchanged. This contributes to the operational reliability of the suction nozzles 1. In the apparatus according to Fig. 1, the seed tray 4 and the feed bin 5 are combined into a single container unit 6. The feed bin is parallel to the seed tray and placed at a lower level. The entire unit can be tilted about a shaft 7 parallel to the bin and the tray. During tilting, seeds are poured from the feed bin onto the seed tray. Fig. 2 shows the seed tray 3 in greater detail. The tray has a porous air-permeable bottom 8 (such as a sintered glass filter, felt or mesh) . Air can be routed via a channel 9 to the underside of the bottom. Air is fed to the underside of the bottom at rate sufficient to make the seed layer in the seed tray to act as a fluidized bed. Picking up of seeds by means of the nozzles 1 from the fluidized bed is easier than from a dense mass of seeds. Simultaneously, the surface of the seed layer stays level and the seeds are prevented from jamming. The air flow also removes lighter rubbish away from the seeds. Furthermore, the seed tray can be vibrated for improved levelling of the seed layer. Fig. 3 illustrates the sowing phase. The suction nozzles 1 are transferred into the sowing position where a matrix of seedling containers 11 movable in the direction of the arrow 10 is aligned below them. When the vacuum is switched off to remov suction from the nozzle tips and an overpressure is applied, the seed releases and falls via a sensor 12 and a guide tube 13 into a cell below. The sensor 12 can be, e.g., an optical or inductive sensor. Its purpose is to detect the fall of a seed from the nozzle 1. If the fall of a seed is not detected, the sowing operation can be repeated for the cell missing a seed. The resowing operation can be accomplished by means of the same nozzle or by way of a patching unit following behind. A particularly suited sensor is such that is a combination of IR emitters (at 880 nm, for instance) and receivers in which the seeds pass through a transparent tube and a plurality of the emitters and receivers are arranged so as to avoid blind angles. The tube diameter is most preferably smaller than 10 mm. Naturally, the motions of the matrix of seedling containers and the nozzles 1 are mutually synchronized with the help of suitably designed mechanical actuator and control elements 14. The suction nozzle 1 can further be complemented by a cleaning arrangement 15 which cleans the nozzle if, for instance, the nozzle fails to pick up a seed on two sub¬ sequent cycles. If the cleaning operation fails to rectify the situation, an alarm is issued by means of an alarm system 16 incorporated in the apparatus. In the embodiment shown in Fig. 4, the container missing a seed is marked by a suitable color marker. Registered detection of a cell missing a seed is routed from the apparatus 14 via a line 17 to a marking apparatus 18. Then, as the cell 11' missing a seed is coincident with the jet nozzle 19 of the marking apparatus, the cell is sprayed with a marker color. The marked cells can afterward be sown manually or routed to another sowing apparatus which identifies the marked cell and sows it with a seed. Instead of color marking, a solid marker piece can be used such as a metal clip, for instance, which is easy to identify by automatic means.

Claims: Claims 1. A sowing device for sowing seeds onto a substrate, said apparatus comprising a suction nozzle unit with one or more suction nozzles (1) having a hole smaller than the seed at its downward oriented tip, a seed tray movable with respect to said nozzle unit below it, a vacuum system for switching on and off suction at the nozzle tips so that a seed can be picked up to the nozzle tip from the seed tray and released at the sowing point onto the substrate, an arrangement for transferring the substrate relative to the sowing device and a system for synchronizing and controlling the motions of the sowing device and the substrate, characterized in that the sowing device further comprises a sensor (9) capable of detecting the release of a seed from the suction nozzle at the sowing point. 2. A sowing device as defined in claim 1, characterized in that the device further comprises an arrangement for resowing of points lacking a released seed. 3. A sowing device as defined in claim 2, characterized in ■ that the resowing arrangement comprises a marking apparatus (18) for marking the points lacking a seed. 4. A sowing device as defined in any of claims 1...3, characterized in that the apparatus further comprises a cleaning arrangement (15) for cleaning a nozzle if it fails to release a seed at the sowing point. 5. A sowing device as defined in any of claims 1...4, characterized in that the apparatus further comprises an alarm system (16) which issues an alarm if a nozzle repeatedly fails to release a seed at the sowing point. 6. A sowing device as defined in any of claims 1...5, characterized in that the seed tray (4) comprises an arrangement (8) for making the seed layer on the seed tray to move as a fluidized bed. 7. A sowing device as defined in any of claims 1...6, characterized in that the seed tray (4) communicates with a larger volume feed bin (5) from which seeds are replenished onto the seed tray when necessary.

Inventors: LEHTINEN JOUKO, VIRTANEN RAUNO, LEHTINEN, JOUKO, VIRTANEN, RAUNO
Applicants: LAENNEN TEHTAAT OY
Application year: 1992
Main classification: A01C7
IPC codes: A01C7