Abstract:
An apparatus for candling eggs includes a transmission system of a luminous flux directed towards the egg to be examined and located in its incubation rack a reception device of the luminous flux transmitted after passing through the mass of the egg, and an automatic analyzer of the recorded signals. The transmission system and the reception device are arranged in a vertical plane or a substantially vertical plane, one beneath the eggs to be examined and the other above the latter. A screen protects the transmission system against smears originating from the eggs in the incubation racks.

Description:
BACKGROUND OF THE INVENTION 
     This present invention relates to an apparatus for candling eggs, i.e. to examine them by transparency, especially in order to select them according to whether they have been fertilised or not. 
     DESCRIPTION OF THE RELATED ART 
     Once eggs from chickens, turkeys, pheasants or other poultry have been fertilised, the embryo and the ramifications of blood vessels being formed are rapidly visible by simple transparency. Sorting between fertilised and non-fertilised eggs can be performed visually, but automatic machines fulfilling this function have been developed for quite a long time. 
     These apparatuses comprise means enabling to determine the absorption factor of a light beam passing through the egg. When this absorption factor reaches a certain threshold, this reflects the presence of an embryo, the sign of fertilisation. 
     The apparatuses for candling eggs comprise a system transmitting a luminous flux intended to go through the egg, a device receiving the flux transmitted and means of computerised analysis of the signals recorded. 
     Each egg is analysed individually and the non-fertilised eggs are then put aside manually or automatically. 
     As a rule, the eggs are analysed directly in their incubation rack arranged horizontally on a conveying device. The transmission system and the reception device are arranged on the same vertical plane, one beneath the said conveying system and the other above the conveying system. The conveying characteristics of the incubation racks are suited to the type of transmitter and receiver used. The structure of these racks enables transparency analysis of the eggs in a vertical plane and the means of analysis used depend on the type or the different types of racks liable to be encountered. 
     During analysis, it may however happen that smears soil the portion of the device, which is situated beneath the conveying system, for example the transmission system of the luminous flux. These smears may originate from broken eggs, dusts or various waste and they are strongly detrimental to analysis quality. 
     The aim of the present invention is to overcome the above prior art inconvenience. 
     To this end, the invention relates to an apparatus for candling eggs of the type composed of a transmission system of a luminous flux directed towards the egg to be examined and located in its incubation rack, and of a device receiving the luminous flux transmitted after passing through the mass of the egg, associated with means of automatic analysis; the transmission system and the reception device are arranged in a vertical plane or a substantially vertical plane, one beneath the eggs to be examined and the other above the latter. 
     According to the invention, this apparatus comprises a screen protecting the transmission system or the reception device, against smears originating from the eggs or the incubation racks notably, by a gravity effect, which protection screen is made of an appropriate material so as not to disturb the luminous flux and which protection screen is associated with means of automatic cleaning. 
     According to a preferred embodiment, the transmission system of the luminous flux is placed beneath the eggs to be examined and the detection device above; the smears protection screen is placed between the eggs and the said transmission system. 
     According to another feature of the invention, the protection screen has the shape of a rotary cylinder in which are located the elements to be protected, and its external face is associated with means of automatic cleaning composed of means intended for the application of a cleaning agent and of a fixed scraping device. 
     According to another feature, the basis at least of the rotary protection cylinder is immersed in a tub filled with a cleaning agent in order to ensure application of a cleaning film on its external surface, under the action of its own rotation. 
     Still according to the invention, the protection cylinder is mounted on a fixed axle via lateral flanges, whereas the assembly of the cylinder on the flanges and the assembly of the said flanges on the fixed axle are made watertight. The fixed axle serves advantageously as a support for the elements to be protected, whereas the power supply and the control means of the latter pass through the said axle. 
     According to another feature, the apparatus comprises means of automatic and continuous conveying of the racks of eggs to be analysed and the protection cylinder is brought into rotation by the driving system of the said conveying means, via a mechanical transmission unit. 
     Still according to the invention, the apparatus comprises a luminous flux transmission system composed of one or several infrared cells and a camera-type detection system, provided with an infrared filter. 
     Preferably, a series of transmission systems are adapted to transmit several luminous fluxes, each oriented towards one of the eggs of a given row to be analysed simultaneously and a single detection camera scans the whole corresponding row, to record, then to enable analysing, the luminous fluxes transmitted. 
     According to another feature, the apparatus comprises a motorised inlet conveyor and a motorised outlet conveyor, between which is placed a supporting tray provided with orifices opposite each egg of the same row, enabling the luminous flux to come through. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     But the invention will be better illustrated, without any limitations, by the following description of a particular embodiment, given solely for exemplification purposes and represented on the appended drawings on which: 
     FIG. 1 is a schematic view of an apparatus for candling eggs according to the invention, as a longitudinal cross section; 
     FIG. 2 is an enlarged partial view showing the cylindrical protection tube of the luminous flux transmission system, as an axial cross section. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The candling apparatus represented on FIGS. 1 and 2 is composed of a transport or conveying plane  1  of the eggs  2 , beneath which is located the transmission system  3  of an infrared luminous flux and above which is placed the detection device  4 , e.g., camera connected to a computerized analyzer  5 . 
     The eggs  2  are arranged in their incubation rack  6  in parallel transversal rows; the racks  6  move in the direction of the orientation arrows  7  and the transmission  3  and detection  4  means are adapted to perform simultaneous analysis of the various eggs in each row. 
     The transport plane  1  is composed of a motorised inlet conveyor  10  and of a motorised outlet conveyor  11 , between which is placed a fixed tray  12  provided with a row of orifices  13  each arranged on the trajectory of a line of eggs. 
     The tray  12  is situated just beneath the conveying plane; its length is smaller than the length of the incubation racks  6  to ensure their being picked up by the outlet conveyor  11  before they are released from the inlet conveyor  10 . 
     The transmission means  3  of the luminous flux are composed of infrared cells  14  arranged on a horizontal ramp  15  placed transversally to the forward travel direction  7 , beneath the tray  12 , and more especially beneath the row of orifices  13 . One or several infrared cells  14  are provided on the ramp  15  at right angle to each orifice  13  in order to generate the infrared luminous flux towards each egg in the same row in the rack  6 . The number of cells  14  per orifice  13  depends on the desirable basic luminous intensity to perform the analysis. 
     Each infrared luminous flux is oriented towards one of the orifices  13  of the tray  12  in order to reach one of the eggs  2  in the same row in the rack  6 . The egg reception cells in the rack  6  comprise an aperture at their bottom so as not to disturb the travel of the light beam. 
     On the other side of the conveying plane, the luminous intensity of the beam transmitted is detected by the camera  4 , which scans the whole width of the same egg row. The lens of the camera is provided with infrared filter  16  capable of taking into account the infrared signals only, in order not to jeopardise the analysis by visible light signals. 
     The computerized analyzer  5  manages the luminous signal transmitted through each egg to assess whether the egg in question has been fertilised or not. This is a pixel-based image analysis on a determined processing surface. 
     The racks  6  move continuously and the analysis task takes place during this motion. Images are recorded and analysed very quickly for each egg. In order to perform a timely analysis, the system takes into consideration the pitch between each egg row in the rack  6  as well as a starting signal sent by a system detecting the arrival of the rack. 
     Beneath the tray  12 , the ramp  15  of infrared cells  14  is accommodated in a cylindrical protection tube  20  made of a material such as glass or plastic, capable of not disturbing the passage of the luminous fluxes. 
     The cylindrical tube  20  is mounted on an axle  21  via lateral flanges  22 . The axle  21  extends transversally to the forward travel direction  7 ; it carries the ramp  15  with the infrared cells  14  and it is preferably hollow to run the power supply and control cables  23  of the said cells. 
     The cylindrical tube  20  is motorised and rotary mounted on the axle  21 , which is fixed. Its base is immersed in a tub  24  containing a cleaning agent  25  (for instance water with a detergent) and a fixed scraper  26  of flexible material, such as rubber, is applied against its external surface. When candling eggs, the protection tube  20  is brought into rotation and its external surface is cleaned permanently by dipping into the cleaning bath  25  and by the action of the scraper  26  that eliminates the residual cleaning film. 
     The scraper  26  extends over the whole length of the protection tube  20 ; it is arranged in order to eliminate the cleaning film, possibly together with the smears, upstream of the passage zone of the luminous fluxes, while taking into account the rotation direction of the tube  20 . 
     The cylindrical tube  20  isolates and protects the transmission system  3  against |any external smear originating for instance from a broken egg or from various debris, and its external surface, subjected to constant action of the cleaning agents  25 ,  26 , is kept clean permanently. 
     The tube  20  can be driven into rotation by a chain, belt or pinion type mechanical transmission unit  27 , connected to a direct motorization unit or preferably to the conveyors  10  and  11 , or to either of them. One of the lateral flanges  22  of the cylindrical tube  20  is provided accordingly. 
     As the base of the protection tube  20  is permanently immersed in the cleaning agent  25 , a tight assembly should be provided between the tube  20  and its lateral flanges  22  on the one hand, and between the said flanges  22  and the fixed axle  21 , on the other hand, thanks to seals, respectively  30  and  31 . 
     The whole portion of the apparatus dedicated to the transmission and the detection of the luminous flux is protected by a casing, not represented, enabling to avoid interference by external light. Beneath the eggs  2  to be analysed, the tray  12  with the orifices  13  enables to limit ingress of possible smears into the transmission system  3 , it also enables to channel the infrared light towards the eggs and to limit still further any interference from external light. 
     The ramp  15  that carries the infrared cells  14  is advantageously mounted in a removable way, with its protection tube  20 , or independently, to allow its replacement in case of breakage or failure or even to allow fitting the transmission means  3  to the type of incubation rack used. 
     With respect to the embodiment illustrated on the figures, it is possible to replace the tub  24  filled with a cleaning agent  25  by nozzles projecting a cleaning agent, without detriment to the cleaning efficiency. 
     It should also be noted that the same protection principle could be used for the detection device  4  in case when the transmission/reception means  3 , 4  would be reverted with respect to the embodiment illustrated on the figures. 
     Moreover, it can be contemplated to adapt this apparatus to provide simultaneous investigation of several egg rows in their incubation rack  6 .