in fig1 is shown a transportation line 1 that extends between a cigarette making plant and a packing plant , the former constituted by a cigarette making machine 2 and the latter by a packing machine 3 . the transportation line 1 can naturally be used to link , one to the other , a number of cigarette making machines 2 and packing machines 3 . commencing at the machine 2 , the transportation line 1 is constituted by a curved channel 4 followed by a vertical channel 5 . the said channels 4 and 5 are defined by the opposite ribbons or belts of the conveyors 6 . the upper extremity of the channel 5 terminates at a virtually horizontal channel 7 , the other extremity of which communicates with the upper extremity of a second virtually horizontal channel or passage 8 whose lower part runs into the inside of an entrance hopper 9 of the machine 3 . in particular , the channel 7 is delimited at the top by a fixed wall 10 , and at the bottom by a belt conveyor 11 mounted around the rollers 12 and 13 , the latter being carried in rotation by a motor 14 . the channels 4 , 5 , 7 and 8 are occupied by a mass of cigarettes 15 produced on the machine 2 , placed crosswise to the major axes of the said channels . the cigarettes 15 are made to move forward along the channel 7 , towards the upper extremity of the passage 8 , in the direction shown by an arrow 16 . in the region of the area where the vertical channel 5 joins the horizontal channel 7 , called the checking position 17 , a checking device shown in its entirety at 18 is provided . the passage 8 communicates , on one side , with a magazine 19 for compensating imbalances , of the type described , for example , in u . s . pat . no . 4 , 254 , 858 in the name of the same applicant as herein . in accordance with the known practice , the said magazine 19 is constituted by a vertical axis cylindrical body , around which is spirally wound , in a way whereby it is able to slide in the two directions under the action of a motor 20 , a thin plate 21 for supporting a layer of cigarettes 15 of virtually a uniform thickness . the magazine 19 is connected to the passage 8 via a duct 22 that runs into the space in between the two spires 23 and 24 of the said thin plate 21 . the underneath part of the said duct 22 is defined by a belt 25 wound endlessly around extremity rollers 26 and 27 , one of which at least is driven . at a point corresponding to the entry area of the magazine 19 a checking device , shown in its entirety at 28 , is provided . the said checking device 18 ( see fig2 ) comprises a diaphragm element 29 that rests on the cigarettes 15 in the area of confluence of the channel 5 and the channel 7 , and has one extremity secured to the wall 10 . the said diaphragm element 29 , made for example of metal mesh , is of a density such as to exert a stabilizing action on the cigarettes 15 underneath but nevertheless is able to &# 34 ; feel &# 34 ; variations in the level of these . in the region of the central area of the diaphragm element 29 , resting thereon is a lever element 30 , one extremity of which is pivotally connected to a wall 31 integral with the wall 10 . above the lever element 30 , the wall 31 supports , by means of a bracket 32 , an analog transducer 33 , that is to say , a transducer able to detect variations in the level of the lever element 30 and , therefore , of the cigarettes 15 , inside the channel 5 , and to provide , for each position adopted by the said element 30 , a corresponding signal to an output 34 ( see also fig4 ). in fig2 and 3 , the said transducer 33 , of photoelectric type , directs a luminous ray towards the lever element 30 , receives the ray reflected back by this and supplies the output 34 with a signal of a voltage proportional to the intensity of the said ray . with reference also to fig4 the output signal of the transducer 33 arrives at the input of an operational amplifier 35 whose gain can be regulated through a negative feedback resistor 36 . present at the output of the operational amplifier 35 is a signal for operating a circuit 37 of a known type , which attends to regulating the speed of the motor 14 of the conveyor 11 . the checking device 28 ( see fig3 ) constitutes a variation to the checking device 18 that is able to be installed in the particularly limited space , called the checking position 38 , delimited by the two spires 23 and 24 . in the latter instance , the transducer 33 carried , by means of a bracket 39 , by the frame of the magazine 19 , directs the luminous ray parallel to the axes of the cigarettes 15 supported by the spire 23 . a plate 40 integral with the body of the transducer 33 carries on the free extremity thereof , angled downwards through 45 °, a reflecting element 41 turned towards the cigarettes 15 . the said reflecting element 41 attends to the sending back towards the transducer 33 of the reflected ray . the output signal of the said transducer 33 , fed to a circuit of the type described previously with reference to fig4 looks after the regulating of the speed of the motor 20 of the magazine 19 . the conveyor system according to the invention , in which the checking devices described are utilized , offers several advantages . firstly , the regulation signal emitted by the described devices 18 and 28 is of analog type whereby every possible level condition of the cigarettes in the checking areas is faithfully reproduced , unlike what occurs with the devices to which reference was made in the introductory part of this text , which furnish output signals that tend to be stepped . as a result of this , the speed of the conveyors in the plant is regulated from one moment to the other with the maximum precision . furthermore , the reduced dimension of the checking devices 18 and 28 enable them to be installed even in areas of the plant where because of their excessive volume , there is not sufficient space for the devices of a known type . it should also be noted that in comparison with the electric circuits utilized in the known devices , the electric circuit connected to the checking devices 18 and 28 described herein is extremely simple and economical . naturally , leaving unchanged the principles of the invention , the variants it would be possible to make to the described conveyor system , without because of them in any way deviating from the framework of the invention , are numerous . for example , the transducer 33 could be constituted by a transducer of capacitive or inductive type , instead of photoelectric . in the preceding description , the installation points considered for the checking devices 18 and 28 have been limited to two though , obviously , any &# 34 ; critical &# 34 ; position in the plant can , in practice , be subjected to a check on the part of devices of the type described . in particular , a checking device 42 similar to the device 18 is placed at the upper extremity of the passage 8 in order to verify the level of the cigarettes 15 there inside and to regulate , through the output signal thereof , additional drive means belonging to the conveyor system in question . as can be seen in fig1 the said lever element 30 is omitted from the said device 42 , and the analog transducer directs its ray directly towards the diaphragm element 29 .
in a conveyor system for conveying articles , such as a system for conveying cigarettes from a cigarette - manufacturing machine along a plurality of channels to a packaging machine , the level of cigarettes in one or more of the channels is measured by an analog - type level detector which generates a continuous output signal used to continuously control the speed of the conveyor system .