Apparatus For Sorting Products According To Their Lengths

Abstract

An electrical apparatus for sorting products according to their lengths. In this apparatus the products are passed through a scanning zone which is provided with a light sensitive cell and a source of illumination arranged so that illumination of the light sensitive cell is interrupted while the product is passing through the scanning zone and an electric pulse is generated while the product is in this zone. This pulse is transmitted from the photocell amplifier to the toggle flip-flop which provides one input to an And gate in the circuit which controls the energization of the solenoid valves controlling the air blasts that deflect the product according to their lengths. This pulse is also transmitted from the photocell amplifier to a signal expanding device which controls a gate between an oscillation generator and an electronic counter so that pulses are transmitted from this generator through this gate to the counter for the duration of the expanded pulse to provide a measure of the product length. The expanded pulse is also supplied to delay circuit to provide a strobe pulse to the logic of this apparatus which supplies three outputs corresponding to the long, medium and short product lengths. These outputs are connected to separate product length flip-flops which are connected to the And gates provided to the circuit controlling the air blast control valves. Each of the And gates have a pair of inputs, one of which is supplied by the output of the toggle flip-flop and the other of which is supplied by the product length flip-flops. Thus, the And gates control which of the air blast solenoid valves is to be energized. If the long product flip-flop supplies a signal to the long product And gate then the long product air blast valve is opened and if the medium or short flip-flop supplies the control signal to the medium or short And gate then the medium or short air blast valve is opened.

Description

DESCRIPTION OF THE INVENTION

This invention relates to apparatus for sorting products according to their lengths.

An object of this invention is to provide an improved apparatus for sorting products according to the lengths thereof.

Another object of this invention is to provide an improved apparatus for sorting products according to the lengths thereof, said apparatus being provided with means that is responsive to alternate products moved along a single file conveyor such that the pulses from succeeding products control this apparatus in a reliable manner and the spacing of the products being sorted may be relatively close without interference.

Still another object of this invention is to provide an improved apparatus for sorting products according to the lengths thereof, said apparatus being provided with dual circuit means responsive to alternate pulses produced when leading edges of succeeding products pass a sensor in single file, the pulses from the succeeding products being used to trigger the dual circuits alternately whereby closer spacing of the products being sorted is possible without interference.

Still another object of this invention is to provide an improved apparatus for sorting products according to their lengths, said apparatus generating a signal while the product is passing between the light and the light sensitive sensor of the scanning zone; said signal is amplified and supplied to a circuit in which it is subjected to a lengthening process to compensate for the signal duration discrepancy occurring in the scanning zone due to the physical dimensions of the components used, said lengthened signal being supplied to a gate which controls the duration during which the pulses are supplied from a pulse generator to an electronic counting and logic circuit which provides different outputs characterized by the different product lengths.

Other and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims and drawing.

In accordance with this invention there is provided an apparatus for sorting products according to their lengths which is an improvement over the apparatus disclosed and claimed in U.S. Pat. No. 3,525,433. The present invention provides a means whereby the lengths of the products may be more accurately determined and whereby the product may be routed into a selected category more efficiently so that a greater volume of products may be processed in a given time. This invention also employs an oscillation generator which supplies pulses that are counted by an electronic counter for different durations depending upon the lengths of the products being scanned. The output of the counter is supplied to the logic of this apparatus which supplies different outputs characterized by the product lengths.

In the present invention a signal is initiated when the leading edge of the product intercepts a light beam to a photocell in the illuminated scanning zone of this apparatus and this signal is amplified. Part of the output from this amplifier is supplied to a signal expanding circuit which provides an expanded pulse to the gate that is connected between the oscillation generator and the electronic counter for controlling the number of pulses transmitted from this generator to the electronic counter. The other part of the output from the photocell amplifier is transmitted to a toggle type flip-flop which is part of the control circuit that controls the energization of the product deflecting means.

The electronic counter provides binary coded output to a comparator network which is connected to manually set switches. These switches are set to determine the lengths to be sorted and the outputs of the decade counters are compared to these settings.

The outputs of the comparator are connected to flip-flop gates which supply the input to the system logic. Outputs from the system logic are connected to the set terminals of the long product flip-flop and to the short/medium product flip-flop. The output of the long flip-flop is connected to one input of the long Nand gate and the output of the short/medium flip-flop is connected to one input of the short/medium Nand gate. These Nand gates are connected to the long one shot multivibrator and short/medium one shot multivibrator, respectively, which control the long solenoid drive and short/medium solenoid driver, respectively. Reset signals for the long flip-flop and the short/medium flip-flop are also obtained from the long Nand gate and a short/medium Nand gate, respectively.

The toggle flip-flop which is connected to the output of the light sensitive cell amplifier is provided with two output circuits which are connected to separate one shot multivibrators. The outputs of these one shot multivibrators are connected together and to the other inputs of the long and medium/short Nand gates. Thus, either output from the toggle flip-flop is supplied to both of the Nand gates. Consequently, if a long product is being processed a pulse of relatively long duration is supplied from the long flip-flop to one input of the long Nand gate and the short pulse from one of the one shot multivibrators functions to activate the long Nand gate and provide an output to another multivibrator which controls the driver for the solenoid valve which controls the air blast to route the long product. Likewise, if a medium/short signal is supplied to the medium/short flip-flop the medium/short Nand gate is activated to provide an output for controlling a multivibrator which controls the medium/short driver and this in turn controls the energization of the solenoid valve which supplies an air blast to route the medium/short product.

Further details and features of this invention will be set forth in the following specification, claims and drawing in which, briefly:

FIG. 1 is a block diagram of the circuit employed in an embodiment of this apparatus;

FIG. 2 is a diagram of the signal expander circuit;

FIG. 3 is a timing chart for the signal expander circuit;

FIG. 4 is a diagram showing the relation between the light source and the light sensitive cell and is used to explain the purpose of the signal expander circuit;

FIGS. 5 and 6 are a detail drawing of the control board employed in this apparatus;

FIG. 7 is a diagram of a voltage regulator employed in the control board; and

FIG. 8 is a timing chart between the input and output of the length sorter.

Referring to the block diagram FIG. 1 reference numeral 100 designates a light sensitive photo diode that is positioned in relation to the single file product conveyor 101 so that light from the light source 102 is intercepted by the product as the product is moved by the conveyor. This part of this apparatus is similar to the corresponding part of the apparatus disclosed in application Ser. No. 621,981 filed on Mar. 9, 1967, which is now U.S. Pat. No. 3,455,444.

The photo diode 100 is connected by a shielded line to the input of the amplifier and Schmitt trigger 103 which produces a square pulse on its output while the product is on the conveyor 101 and intercepts the light passing from the light source 102 to the photo diode. The square pulse from the amplifier and Schmitt trigger 103 is supplied to line 105 which is connected to the input of the signal expander 104 and also to the input of the toggle flip-flop 106 which is provided with two output terminals 107 and 108.

The output of the signal expander 104 comprises one of the inputs to the gate 201; another input to this gate is provided by the oscillator 118 which generates pulses of a predetermined frequency that is adjustable by the resistor 121 and which frequency is correlated with the speed of the conveyor 101.

The pulse from the signal expander 104 is also supplied by line 113 to the multivibrator 203 and to the alarm 126. The computing and logic apparatus which is enclosed by the broken line 200 is similar to the apparatus disclosed in application Ser. No. 751,815 which is now U.S. Pat. No. 3,525,433, and reference is made to this patent for the details of construction thereof. This apparatus includes the gate 201 which is provided with outputs to the decade counters 204 and to the delay multivibrator 202 which supplies a 20 microsecond delayed reset signal to the counters 204 and also a 20 microsecond delayed reset signal to the flip-flops in gates 208 and 209. Delay multivibrator 202 also provides a 10 microsecond delayed signal to one of the Nand gates of the spurious signal rejector 203. The input of another Nand gate of the spurious signal rejector 203 is connected to the output of the signal expander 104. The spurious signal rejector 203 supplies the strobe signal to the separator logic 210.

The binary coded decimal output of the decade counters 204 is supplied to the signal inverter 205 which is connected to the comparator network 206. Thumbwheel switches 207 are connected to the comparator network 206 to select the product length ranges to be classified into the short/medium and long length products. The outputs of the comparator network 206 are connected to the gates 208 and 209 and the outputs of these gates are connected to the system logic 210 in which these outputs together with the strobe signal determine which output line 211, 212 or 213 is to be energized. Output 211 is connected by line 215 to the long flip-flop 217 and outputs 212 and 213 are connected to the selector switch 214 so that either output 212 or 213 may be connected by this switch to line 216 which is connected to the short/medium flip-flop 218. Thus, line 215 when energized provides the set signal for flip-flop 217 and line 216 when energized provides the set signal for flip-flop 218.

Toggle flip-flop 106 is provided with two outputs 107 and 108 which are connected to the inputs of one shot multivibrators 219 and 220, respectively. Trimmer potentiometers 221 and 222 are connected to the one shot multivibrators 219 and 220, respectively, for adjusting the delay provided in these one shots and the variable controls of these potentiometers are connected together mechanically so that these devices are adjusted simultaneously. The outputs of the one shot multivibrators 219 and 220 are connected together and to the terminals 225 and 227 of the long gate 223 and medium/short gate 224, respectively. The long flip-flop 217 has the output thereof connected to the other input terminal 226 of the long gate 223 and the short/medium flip-flop 218 has the output thereof connected to the other input terminal 228 of the short/medium gate 224.

The output of the long gate 223 is connected to the input of the long duration one shot multivibrator 229 and also provides the reset signal for the long flip-flop 217. Likewise, the output of the short/medium gate 224 is connected to the input of the short/medium one shot multivibrator 230 and also provides the reset signal for the short/medium flip-flop 218. The driver 233 for the long product solenoid 235 is connected to the output of the one shot multivibrator 229 and the short/medium driver 234 which drives the short/medium product solenoid 236 is connected to the one shot multivibrator 230. Multivibrators 229 and 230 are provided with trimmer potentiometers 231 and 232, respectively, so that the duration of the delay in these multivibrators may be manually adjusted. Solenoid 235 controls the air jet for deflecting the long length products and solenoid 236 controls the valve of the air jet for deflecting the short/medium length products.

In FIG. 2 there is shown a detail wiring diagram of the pulse expanding or stretching circuit 104 which is provided with a transistor 105 having the base thereof connected to the amplifier output 103. The collector of transistor 105 is connected to the positive 5 volt line 106 through resistor 107 and it is also connected to line 108 which leads to the base of transistor 109 and to the coupling capacitor 110. Coupling capacitor 110 is connected to the terminal 9 of the Nand gate 111. Nand gates 111 and 112 are connected as a flip-flop and terminal 8 of gate 111 is connected to terminal 12 of gate 112. Terminal 10 of gate 111 is connected to terminal 11 of gate 112 which is also connected to the output line 113.

The collector of transistor 109 is connected to the positive 5 volt line 106 through resistor 114 and to line 115 which goes to one side of the coupling capacitor 116. The other side of this capacitor is connected to terminal 1 of the Nand gate 117. Nand gates 117 and 118 are connected as a one shot multivibrator. Terminal 2 of gate 117 is connected to terminal 6 of gate 118 and terminal 3 of gate 117 is connected to the line 119 which leads to one side of each of the capacitors 120 and 121. The other side of capacitor 120 is connected to terminals 4 and 5 of gate 118, and the other side of capacitor 121 is connected to terminal 13 of gate 112. Capacitors 110, 116 and 121 together with resistors 122, 123 and 124, respectively, function as differentiating circuits.

Thus, the leading edge of the negative-going pulse 125 supplied to line 108 by transistor 105 is differentiated in circuit 110-122 to provide the sharp pulse 126 to the terminal 9 of the flip-flop including gates 111 and 112 so that the flip-flop starts generating pulse 127. The timed relation of these pulses is shown in FIG. 3. Pulse 125 is also supplied to the base of transistor 109 which functions as an inverter and provides the pulse 125a on the line 115 which is connected to the collector thereof and which corresponds in duration to pulse 125. Differentiating circuit 116-123 provides a sharp pulse 128 from the trailing edge of pulse 125a and this sharp pulse is supplied to terminal 1 of gate 117 of the one-shot multivibrator. This multivibrator produces pulse 129 on line 119 and differentiating circuit 121-124 produces a sharp pulse 130 from the trailing edge of pulse 129. Pulse 130 is supplied to terminal 13 of gate 112 and functions to reset the flip-flop 111-112. Thus the pulse 127 supplied to line 113 by the flip-flop 111-112 is lengthened or expanded so that its time interval corresponds to the combined time of pulses 125 and 129.

In FIG. 4 there is shown a view of the physical relationship between the light source 102 and the light sensitive cell 100. The product P conveyed between the light source and light sensitive cell intercepts the light rays from the light source. When the product is in the position shown by P.sub.1 it intercepts the light from the source 102 to the photodiode 100. This initiates the start of pulse 125 by the amplifier Schmitt trigger 103. When the product is conveyed to the position shown by P.sub.2 the trip point is reached and the pulse 125 is cut off. However, in this arrangement the length of the pulse corresponding to the product is actually shortened by the time it takes the product to move the distance C, that is the length of pulse 125 does not correspond to the actual time that the product requires to move through the scanning zone. The circuit shown in FIG. 2 is used to compensate for this discrepency by lengthening the pulse to the length of pulse 127 which is accomplished by adding the length of pulse 129 to that of pulse 125.

In FIGS. 5 and 6 there is shown the diagram of connections of the components of the control board which is that portion of the circuit shown in FIG. 1 enclosed by the broken line 300. The toggle flip-flop 106 employs two Nand gates 301 and 302. Nand gate 301 is provided with three terminals 11, 12 and 13 and Nand gate 302 is also provided with three terminals which are designated by 8, 9 and 10. Terminals 11 and 8 of gates 301 and 302, respectively, form the outputs 107 and 108 shown in FIG. 1. Feedback resistors 303 and 304 are connected between the terminals 11 and 12 of gate 301 and terminals 8 and 10 of gate 302, respectively. Terminal 11 of gate 301 is connected to terminal 9 of gate 302 and terminal 8 of gate 302 is connected to terminal 13 of gate 301. Input from the 160 line 105 is supplied to these gates through capacitors 305 and 306 which are connected between the line 105 and terminal 12 of gate 302 and terminal 10 of gate 302, respectively.

The device 106 functions as a toggle flip-flop and the outputs 107 and 108 thereof are connected to the one shot multivibrators 219 and 220, respectively, so that each of these multivibrators receives alternate pulses from the flip-flop. Each of these multivibrators is in the form of an integrated circuit and each is provided with terminals designated by the numbers 1, 3, 4, 5, 7, 9, 10, 11 and 14 as shown. Terminals 3 and 4 of each multivibrator are connected together and these terminals of multivibrator 219 are connected to the output terminal 107 of the toggle flip-flop. Likewise these terminals of multivibrator 220 are connected to the output terminal 108 of the toggle flip-flop. Resistors 307 and 309 are connected between terminals 5 and 14 of each multivibrator 219 and 220, respectively, and terminal 14 of each multivibrator is connected to the positive 5 volt line. Terminal 7 of each multivibrator is connected to the ground line G and capacitors 308 and 310 are connected between the terminals 10 and 11 of each multivibrator, respectively.

One side of each of the variable resistors 311 and 312 is connected to terminal 9 of each multivibrator and the other sides of these resistors are connected to variable resistors 313 and 314, respectively. Variable resistors 313 and 314 are connected to the positive 5 volt line. These variable resistors are used to control the signal delay in the multivibrators 219 and 220. Resistors 311 and 312 may be positioned on the control board whereas resistors 313 and 314 may be positioned outside where they are readily accessible, and these latter resistors 313 and 314 may be operated by a common manual control. The durations of the signals from the one shot multivibrators 219 and 220 are set by these resistors to delay the action of the solenoid valves and time the air blasts controlled by these valves to coincide with the predetermined product passing by these valves. This delay is determined by the speed of the conveyor, the solenoid valve turn-on time and the distance from the photo sensitive cell or photodiode to the air nozzles controlled by the solenoid valves.

A diode rectifier 315 and differentiating circuit including capacitor 316 and resistor 319 are connected between the output terminal 1 of one shot multivibrator 219 and input terminal 5 of the Nand gate 223. Likewise, the output terminal 1 of one shot multivibrator 220 is coupled to the input terminal 9 of Nand gate 224 by the diode rectifier 318 and differentiating circuit including capacitor 319 and resistor 320. However, terminals 5 and 9 of Nand gates 223 and 224 are connected together so that output from either one of the one shot multivibrators 219 or 220 is supplied to either one of these Nand gates.

The other input terminals 4 and 10 of Nand gates 223 and 224 are connected to the outputs of flip-flops 217 and 218, respectively, as shown in FIG. 6. Two Nand gates 322 and 323 are connected together to form the flip-flop 217 and two Nand gates 324 and 325 are connected together to comprise the flip-flop 218. Terminals 1 and 3 of Nand gate 322 are connected to terminals 11 and 12, respectively, of gate 323 in flip-flop 217. Terminal 2 of Nand gate 322 is connected to ground through resistor 326 and terminal 13 of Nand gate 323 is connected to ground through resistor 327. Coupling capacitor 328 is provided between the terminal 2 if Nand gate 322 and the line 215 which leads to the long product terminal 211 of the logic as shown in FIG. 1. Output terminal 3 of Nand gate 322 of flip-flop 217 is connected to the input terminal 4 of Nand gate 223 as shown in FIG. 5. Thus, when 780 as flip-flop 217 receives a signal corresponding to a long product over line 215 this flip-flop is set and supplies a signal to terminal 4 of Nand gate 223.

Flip-flop 218 is similar to flip-flop 217 and terminal 1 of Nand gate 324 thereof is connected to terminal 6 of Nand gate 325 and terminal 3 of gate 324 is connected to terminal 4 of gate 325. Terminal 2 of gate 324 is connected to ground through resistor 330 and is coupled to the medium-short product line 216 through a capacitor 332. Terminal 5 of gate 325 is connected to ground through resistor 331 and is coupled to the reset line by capacitor 333. When the medium-short product signal is received from the logic 210 shown in FIG. 1 over line 216, flip-flop 218 is set and supplies a signal to terminal 10 of Nand gate 224 shown in FIG. 5.

The output terminals 6 of Nand gate 223 is connected by line 334 to the input terminal 3 of the one shot multivibrator 229. Line 334 extends to flip-flop 217 and provides the reset signal for this flip-flop. Likewise, the output terminal 8 of Nand gate 224 is connected by line 335 to the input terminal 3 of the one shot multivibrator 230, and this line also extends to flip-flop 218 to provide the reset signal for this flip-flop. Test switches 215a and 216a are provided for grounding the reset lines 215 and 216, respectively, through resistors 215b and 216b. Capacitors 215c and 216c are connected across resistors 215b and 216b, respectively.

The signal delay in one shot 229 may be adjusted by the variable resistor 231 which is connected in series with the resistor 231a to terminal 9 of the one shot. Right hand terminal of resistor 231 is connected to the positive 5 volt line. Likewise, the signal delay in one shot 230 may be adjusted by the variable resistor 232 which is connected in series with resistor 232a to terminal 9 of the one shot and the right hand terminal of resistor 232 is connected to the positive 5 volt line.

One shot multivibrators 229 and 230 are integrated circuit devices and each of these devices is provided with terminals 1, 3, 4, 5, 7, 9, 10, 11 and 14. Terminals 5 and 14 of the one shots 229 and 230 are connected together to the positive 5 volt line. These terminals of one shot 229 and one shot 230 are connected to the emitter of transistor 336, and to emitter of transistor 337, respectively. Transistors 336 and 338 form the driver 233 and transistors 337 and 339 form the driver 234 shown in this FIG. 1. Resistors 340 and 341 are connected in series between the 5 volt line and the terminal 1 of one shot 229 and the junction of these resistors is connected to the base of transistor 336; this junction is also coupled by capacitor 342 to ground.

The collector of transistor 336 is connected through resistor 343 to the base of transistor 338 to supply the signal to this transistor. The base of transistor 338 is also connected to ground through resistor 344. The emitter of transistor 338 is connected to ground the the collector thereof is connected to line 235a which is connected to the solenoid 235 that controls the air jet valve for deflecting the long product. A Zener diode 338a is connected across the transistor 338 to protect this transistor from voltage surges developed in the solenoid circuit.

The connections of the driver transistors 337 and 339 are similar to those of transistors 336 and 338. In this case resistors 345 and 346 are connected in series between the 5 volt line and terminal 1 of one shot 230. The junction between these resistors is connected to the base of transistor 337 and also to the capacitor 347 which is connected between the base of transistor 337 and ground. The collector of transistor 337 is connected to the base of transistor 339 through resistor 348. The base of transistor 339 is also connected to ground through resistor 349. The emitter of transistor 339 is connected to ground and the collector thereof is connected to line 236a which leads to the solenoid 236 shown in FIG. 1. This solenoid controls the air jet valve for the medium-short product. A Zener diode 339a is connected across the transistor 339 to protect this transistor from voltage surges developed in the solenoid circuit.

The voltage regulator 360 for providing a constant 5 volt supply is shown in FIG. 7 and it is provided with four transistors 361, 362, 363 and 364 which are connected to provide a constant 5 volt supply from the input of 18 volts connected to the line 365. Resistor 366 and Zener diode 367 are connected in series between the line 365 and ground. The potentiometer 368 is connected across Zener diode 367 and the variable contact of this potentiometer is connected to the base of transistor 362 to provide a bias thereto which is stabilized by the Zener diode 367. The emitters of transistors 362 and 363 are connected together to resistor 369 and to ground. Thus the voltage drop across resistor 369 depends on the current flow through both transistors 362 and 363. The collectors of these transistors are connected to line 365 through resistors 370 and 371, respectively. Bias for the base of transistor 363 is provided from the 5 volt line so that any variations in this voltage are transmitted to the base of this transistor. The base of transistor 361 is connected to the collector of transistor 362 and the collector of the latter transistor is connected through resistor 372 to the base of transistor 364. Thus, the 5 volt line is supplied through the transistor 364 from line 365 and the bias on the base of transistor 364 is controlled by transistors 361, 362 and 363.

In FIG. 8 there is shown a timing chart for this apparatus. When the leading edge of the product P.sub.1 intercepts the light from the source 102 to the photocell 100, a pulse 400 is produced in the amplifier Schmitt trigger 103 and a pulse 401 is supplied to the toggle flip-flop 106. Pulse 402 is transmitted from the output of the toggle flip-flop to the one shot multivibrators 219 or 220. Pulse 403 is generated by either of the one shots 219 or 220. Pulse 404 is supplied by the logic over either lines 215 or 216 to the flip-flops 217 or 218. In this case it was assumed that the logic 210 produced a signal corresponding to a long product and so it is assumed that the pulse 404 is transmitted to flip-flop 217 to set this flip-flop. Flip-flop 217 produces pulse 405. Of course, if the pulse 404 received from logic 210 corresponded to a medium-short product then this pulse would be transmitted to flip-flop 218 to set this flip-flop instead of flip-flop 217. Pulse 405 would then be produced by flip-flop 218. Pulse 406 is produced at the end of the one shot multivibrator pulse 403 and is supplied to Nand gates 223-224. Gate 223 is receiving pulse 405 from flip-flop 217 and at the end of pulse 405 Nand gate produces output pulse 407 which is transmitted to the one shot multivibrator 209 and also to the reset terminal of flip-flop 217. One shot multivibrator 229 produces the pulse 408 which is supplied to the driver 233 for the air blast solenoid valve control 235 which releases the air blast from the nozzle 409 to deflect the product shown at P.sub.2 which has arrived at the nozzle. Pulse 408 must be long enough to permit the air blast to deflect the product. The delay indicated at 410 is provided in the Nand gate 223 or 224 to delay the reset signal to the flip-flops 217 or 218 so that these flip-flops do not turn off the affected gate too fast.

While I have shown and described a certain preferred embodiment of the invention, it is apparent that the invention is capable of variation and modification from the form shown so that the scope thereof should be limited only by the proper scope of the claims appended hereto.

Claims

What I claim is:

1. In apparatus for sorting products according to their lengths, the combination comprising means moving a single file of the products to be sorted through a scanning zone at a predetermined speed, said scanning zone having a light source and a light sensitive device, an amplifier having the input thereof coupled to said light sensitive device, a toggle flip-flop connected to the output of said amplifier, said amplifier providing an output pulse to trigger said toggle flip-flop when the leading edge of a product is sensed in said scanning zone, a pulse generator for generating pulses at a predetermined rate, pulse counting means, a gate, means supplying a pulse characterized by the length of said product to condition said gate for transmitting pulses from said generator to said counting means for the duration of the pulse, means responsive to said counting means producing product length signals characterized by different product lengths, a pair of signal delay devices, said toggle flip-flop having a pair of outputs connected to said signal delay devices separately so that said signal delay devices are activated by said flip-flop output alternately, and means responsive to said product length signals and to the signal from said signal delay devices controlling separating means which separates the products scanned according to their lengths.

2. In apparatus for sorting products according to their lengths, the combination as set forth in claim 1, further characterized in that said pair of signal delay devices each comprise a one shot multivibrator with the outputs thereof connected together to said last mentioned signal responsive means.

3. In apparatus for sorting products according to their lengths, the combination as set forth in claim 2, further characterized in that said last mentioned signal responsive means includes at least two flip-flops which are responsive to different product length signals respectively.

4. In apparatus for sorting products according to their lengths, the combination as set forth in claim 3, further characterized in that the outputs of said two flip-flops are connected to separate Nand gates, the outputs of said one shot multivibrators also being connected to said Nand gates.

5. In apparatus for sorting products according to their lengths, the combination as set forth in claim 4, further characterized in that the outputs of said Nand gates are connected separately to two additional one shot multivibrators which produce pulses having lengths corresponding substantially to the time required for a product to be moved by said moving means from said scanning zone to said separating means so that said separating means is activated thereby at the proper time for separating selected products.

6. In apparatus for sorting products according to their lengths, the combination as set forth in claim 5, further characterized in that the outputs of said Nand gates are also separately supplied to said two flip-flops for resetting these flip-flops.

7. In apparatus for sorting products according to their lengths, the combination comprising means moving a single file of the products to be sorted through a scanning zone at a predetermined speed, said scanning zone having a light source and a light sensitive device, an amplifier having the input thereof coupled to said light sensitive device, a toggle flip-flop, means connecting said toggle flip-flop to the output of said amplifier, said amplifier providing an output pulse to trigger said toggle flip-flop when the leading edge of a product is sensed in said scanning zone, means expanding said output pulse a predetermined amount to compensate for the shortened pulse obtained from the scanning of the product, a pulse generator for generating pulses at a predetermined rate, pulse counting means, a gate controlled by said expanded pulse for transmitting pulses from said generator to said counting means, means responsive to said counting means producing signals characterized by different product lengths, one shot multivibrator means, means responsive to the output of said toggle flip-flop and to said last mentioned signals for activating said one shot multivibrator means, solenoid valve means controlling product separating jets, and means responsive to said multivibrator means controlling said solenoid valve means to separate the products according to their lengths.

8. In apparatus for sorting products according to their lengths, the combination as set forth in claim 7, further characterized in that said output pulse expanding means comprises a one shot multivibrator having means for producing said expanded pulse of predetermined duration.

9. In apparatus for sorting products according to their lengths, the combination as set forth in claim 8, further characterized in that the physical size of said light source is substantially larger than that of said light sensitive device so that when the product is moved therebetween the period of interruption of the light transmitted from said source to said light sensitive device does not correspond to the period of the pulse generated in the output of said light sensitive device, said one shot multivibrator being adjusted so that the pulse produced thereby is expanded by an amount to substantially compensate for the discrepency between said period of interruption and said output pulse.

10. In apparatus for sorting products according to their lengths, the combination as set forth in claim 7, further characterized in that said means responsive to the output of said toggle flip-flop comprises two one shot multivibrators which are connected to said toggle flip-flop to be activated by alternate pulses from said toggle flip-flop whereby closer spacing of the products moved through said scanning zone is possible.

11. In apparatus for sorting products according to their lengths, the combination as set forth in claim 10, further characterized in that the outputs of said two one shot multivibrators are connected together to provide one input to each of two Nand gates, flip-flops connected to said counting means responsive means, said last mentioned flip-flops providing the other input to said two Nand gates and the outputs of said Nand gates being connected to said one shot multivibrator means.

12. In apparatus for sorting products according to their lengths, the combination comprising means moving a single file of the products to be sorted through a scanning zone at a predetermined speed, said scanning zone having a light source and a light sensitive device, an amplifier having the input thereof coupled to said light sensitive device, a toggle flip-flop, means connecting said toggle flip-flop to the output of said amplifier, said amplifier providing an output pulse to trigger said toggle flip-flop when the leading edge of a product is sensed in said scanning zone, means expanding said output pulse a predetermined amount to compensate for the shortened pulse obtained from the scanning of the product, a pulse generator for generating pulses at a predetermined rate, pulse counting means, a gate controlled by said expanded pulse for transmitting pulses from said generator to said counting means, means responsive to said counting means producing different product length signals, means responsive to the output of said toggle flip-flop and to said last mentioned signals, solenoid valve means controlling product separating jets, and means responsive to said last mentioned means controlling said solenoid valve means to separate the products according to their lengths.

13. In apparatus for sorting products according to their lengths, the combination as set forth in claim 12, further characterized in that said toggle flip-flop is connected to a pair of signal delay devices which are energized alternately from said toggle flip-flop and said product length signals are supplied to different product length flip-flops.

14. In apparatus for sorting products according to their lengths, the combination as set forth in claim 13, further characterized in that said means controlling said valve solenoid includes additional signal devices having inputs thereof connected to Nand gates, said Nand gates being controlled by signals from said product length flip-flop and from said pair of signal delay devices.