US3766394A

US3766394A - Device for the optical-electrical scanning of an information carrier

Info

Publication number: US3766394A
Application number: US00173374A
Authority: US
Inventors: G Gottschal
Original assignee: Franz Morat GmbH
Current assignee: Franz Morat GmbH
Priority date: 1970-08-22
Filing date: 1971-08-20
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: DE2041795A1; GB1336680A; CS151413B2; ES394875A1; NL7111034A; CH523570A; DE2041795B2; FR2104423A5; BE771666A; AT332518B; ATA679071A

Abstract

A device for the optical-electrical scanning of an information carrier with a scanning device especially for use with a knitting machine having at least one lamp, at least one photoelectric cell, a transport means for establishing relative motion between the information carrier and the scanning device, including a control circuit to maintain a preselectable rated intensity in said lamp, a voltage limiting circuit for the lamp voltage, a first time member associated with said voltage limiting circuit through which the lamp voltage during the switch-on process is at first limited to a value above the preselected lamp voltage and a preselected time span after the switch on process to nominal lamp voltage and that the transport means is activated after attainment of a rated intensity.

Description

United States Patent [191 Gottschal DEVICE FORTHE OPTICAL-ELECTRICAL SCANNING OF AN INFORMATION CARRIER Inventor:

[75] Gernot Gottschal, Boblingen,

Germany [73] Assignee: Firma Franz Morat GmbH,

Hessbruhlstrasse, Germany Filed: Aug. 20, 1971 Appl. No.: 173,374

[30] Foreign Application Priority Data Sept. 22, 1970 Germany i. P 20 41 795.2

[52] US. Cl.....; 250/205 R [51] Int. Cl. G0lj 1/32 [58] Field of Search 250/205, 206, 214, 250/219 D, 219 FR; 307/311; 315/149, 151,

References Cited UNITED STATES PATENTS 11/1964 Passmore 250/219 FR Primary Examiner.lames W. Lawrence Assistant Examiner-D. C. Nelms Attorney-John Lezdey et a1.

[5 7] ABSTRACT A device for the optical-electrical scanning of an information carrier with a scanning device especially for use with a knitting machine having at least one lamp, at least one photoelectric cell, a transport means for establishing relative motion between the information carrier and the scanning device, including a control circuit to maintain a preselectable rated intensity in said lamp, a voltage limiting circuit for the lamp voltage, a first time member associated with said voltage limiting circuit through which the lamp voltage during the switch-on process is at first limited to a value above the preselected lamp voltage and a preselected time span after the switch on process to nominal lamp voltage and that the transport means is activated after attainment of a rated intensity.

6 Claims, 4 Drawing Figures i9 Amplifier Ad sfz'n Membefl 35 J j 11 C'anzrol C'z'r'cur'l i 7 %;552? 47 i i l ,{z'mift'ng Circa/if g I i 48 37' Wu: 6 I i 49 Circuit i l 5.] l 54 I Time Memev'! L 64 A 55 g 67 r'l I A 53 i I I Mofar PMENTEU B 16 I973 SHEET 30F 4 FIG. 3

DEVICE FOR THE OPTICAL-ELECTRICAL SCANNING OF AN INFORMATION CARRIER BACKGROUND OF THE INVENTION This invention relates to the field of optical-electrical scanning devices for information carriers.

In using known scanning devices, the information carriers are considerably stressed thermally by the lamps in order to achieve a high degree of scanning accuracy and speed. If the information carrier during a scanning process is step by step or continually transported through a crack or opening located between the lamps and a photoelectric cell, the heat generated by the lamp is distributed over a larger surface on the information carrier. Especially in case of slow feeding speeds or in case of protracted idleness of the information carrier i.e. when the information carrier is at a standstill for a longer period of time the information carrier may be so greatly heated up that it will be damaged or permanently deformed. This is undesirable .because the information carrier is generally intended for multiple use.

To avoid this disadvantage, there is-a possibility of providing heat filters which absorb a certain portion of the ultrared radiation of the lamp which is not required for scanning. Heat filters, however, entail the disadvantage that they offer either incomplete heat protection or that they require such a great increase in the lamp output, especially in connection with film strips as information carriers, that the lamps lifetime is considerably reduced.

Another possibility of avoiding the above-mentioned disadvantage consists in disconnecting the lamp when the information carrier is at a standstill. But this entails the disadvantage that the lamp is not immediately ready for operation again when it is turned on again because, when the nominal voltage is applied, the rated intensity is attained only in, for example, 500 milliseconds, as a function of the dimensions of the filament. This disadvantage is particularly serious when the information carrier is to be used for the automatic control of a machine, for example, a knitting machine, whereby every marking of the information carrier, which is scanned produces a control signal which activates some member of the machine, for example, a needle selection device on the knitting machine. If the information carrier in such a case is to be adjusted step by step to a very specific marking from the standstill several times very briefly by activating a switch so that a control processassociated with it can be controlled on the machine, then a time member would have to be connected with the switch in order to set the information carrier in motion only at a delay of about 500 milliseconds.

Such a delay in any switch activation is not desirable for the operating personnel because during adjustment or during the repair and maintenance of the machine it is very frequently necessary to adjust for a certain marking.

OBJECTS OF THE INVENTION An object of this invention'is to create a scanning device by means of which, on the one hand, it is possible to prevent the excessive heating of the information carrier in a simple manner and, on the other hand, which will permit the fastest possible start of the scanning of the information carrier.

A further object of this invention is to provide a scanning device which can be used at slow feeding speeds or when the information carrier is at a standstill for a long period of time.

It is a still further object of this invention to provide a scanning device for use in connection with a knitting machine which can have greater start in a scanning operation.

SUMMARY OF THE INVENTION The present invention relates to an optical-electrical scanning device. More particularly, this invention relates to an optical-electrical scanning device for use in connection with knitting machines.

This invention relates to a device for the opticalelectrical scanning of an information carrier with a scanning device consisting of lamp means and photoelectric cells, a feeder means to establish a relative movement between the information carrier and the scanning device, a control circuit to maintain a preselectable rated intensity of the lamps in the lamp means, and a limiting circuit for the lamp voltage.

In the device-of this invention there is a time member associated with a voltage limiting circuit and through the time member a lamp voltage is at first limited to a value essentially above the nominal voltage and to a preselected span of time after adjusting for the nominal voltage and a preselected span of time and after the switch-on process for the nominal voltage. The feeder device begins to operate only after the rated intensity has been attained.

The automatic limitation of the lamp voltage to a.

smaller value after the expiration of a certain span of time offers the advantage that a destruction of the lamp can reliably be prevented even if the nominal intensity is not attained because of some disturbance or if it is attained but not indicated.

Switching the maximum voltage from a high value to a smaller value, which generally corresponds to the nominal voltage of the lamp, is therefore a process which is controlled by a time member which is activated by means of the switch-on process and which reliably switches prior to the moment at which the lamp would be destroyed if it were to be further overloaded.

According to a preferred further development of the invention, the rated intensity of the lamp is maintained, during the disconnection or cutoff process up till the final termination of the scanning. If the scanning is accomplished by moving the information carrier .with're-'v lation to the scanning device then the end of the scanning is attained and not ,when the transport device of the information carrier is turned off but only when the information carrier finally comes to a standstill. The

lamp must be kept at its rated intensity up to that mo- BRIEF DESCRIPTION OF THE DRAWINGS V A FIG. 1 is a schematic diagram of an optical-electrical scanning device for an information carrier suitable to control a circular knitting machine;

The invention offers three essential advantages. This FIG. 2 is a schematic diagram of a switching circuit according to the invention for the operation of the lamp and the feeder device for the information carrier of FIG. 1;

FIG. 3 is a schematic diagram of the time curve of the intensity, the current, and the voltage of the lamp of the scanning device, and

FIG. 4 shows an example of the control circuit and the limiting circuits of the switching circuit of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the needle cylinder 1 of a circular knitting machine, which can be rotated in the direction of the arrow, is illustrated schematically. The remaining parts of a circular knitting machine are known and are not necessary for the understanding of the invention. Cylinder needles 3, which may be moved up and down independently of each other, are arranged on needle cylinder 1. To select those cylinder needles 3, which may or may not be involved in the knitting process, there is provided control magnet systems 5 which have electrical control signals via a line 19. The control signals are received through the scanning of an information carrier 7 which by means of transport rollers 9 is transported past a scanning device 11. The information carrier, for example, is a film strip with opaque and translucent markings. The scanning device 1 1 contains at least one lamp 13 which, for example, can be an incandescent lamp, and at least one photoelectric cell (not shown). The electrical signals obtained through scanning are fed to an electronic system 17 and, after amplification and standardization, are fed to a pertinent control magnet system 5.

A stepping motor 21 is used to drive the transport rollers 9, whereby a transmission or reduction gear 23 can be provided between the stepping motor 21 and the transport rollers 9. The stepping motor is connected via lines 25, the electronic system 17, and a line 27, with a timing impulse generator 29 which when the needle cylinder is rotated generates one cycle signal per needle moving past and through this signal the information carrier 7 is transported further one step at a time.

As illustrated in FIG. 2, lamp 13 is connected to a battery 35 via a resistance 31 and an adjusting member 33. By means of adjusting member 33, the output supplied to lamp 13 can be adjusted to any desired value. A photoelectric sensor 37 is used to determine the actual intensity of lamp 37 and gives an electrical signal which is proportional to the intensity which is supplied in an amplified manner to an amplifier 39 and which is then supplied to a comparison circuit 41. In the comparison circuit the electrical signal is compared with a signal which is proportional to a preselected rated intensity and which is supplied via a line 43. The difference between the signals that are proportional to the actual intensity and the rated intensity is fed into a con! trol circuit 45 which gives off a difference signal which is proportional to this difference and which is amplified and then fed to an adjusting member 33. As a function of the size of the difference signal, the adjusting member 33 is then adjusted in the correct direction until the difference signal disappears or until lamp 13 has attained the desired rated intensity.

To limit the lamp current, there may be used a limiting circuit 47. The current which flows through lamp 13 is measured on a resistance 31. The measurement signal is supplied to the limiting circuit 47 via a line 48. A signal is supplied to another input of the limiting circuit 47 via a line 49 and this signal represents a maximum permissible lamp current 1 As long as the actual value of the lamp current is below the value I the limiting circuit 47 have no influence on the remaining circuit arrangement.

However, if the actual value of the lamp current exceeds the value I then the limiting circuit 47 gives off a signal which activates a switching member located in the control circuit 45 in such a manner that the difference signal given off by the control circuit 45 will remain limited to the value which just happens to be present at the moment. As a result, the adjusting member 33 remains in its momentary position and the lamp current constantly retains the value l even if the rated intensity of the lamp has not yet been attained.

The voltage applied to lamp 13 is limited by a limiting circuit 50. The limiting circuit 50 is supplied on the one hand, via a line 51, with the signals proportional to the actual voltage and, on the other hand, via a line 52, with signals which are in a relationship with a preselected maximum lamp voltage U In case the actual voltage of lamp 13 is greater than U the limiting circuit 50 gives off a signal which is supplied to the control circuit 45 and which causes the difference signal, appearing at the output of the control circuit 45, to remain constant, regardless of the actual intensity of the lamp which just happens to be there at that time, so long as the actual voltage of lamp 13 is greater than nwr- According to one preferred version of the invention, the maximum lamp voltage U can be selected differently. For this purpose there may be used a turn-on and tum-off switch 53 which is connected with a switch 55 by means of a time member 54. The switch S5 is connected, on the one hand, to the line 52 and, on the other hand, to a point 59. The line 52 is furthermore connected with a point 61. Point 59 is on a relatively high potential U whereas point 61 is on a relatively low potential U for example, the nominal voltage. Time member 54 is so designed that the switch 55 is likewise closed when the turn-on and the turn-off switch 53 is closed but it is opened again after a certain time delay. As a result the line 52, immediately after the turn-on process, is at first at a relatively high and then at a relatively low potential. X

With the turn-on and turn-off switch 53 there is furthermore connected a switching member 63 through which a motor 65 is turned on at the moment of switchon and this motor brings about rotation of the needle cylinder 1 of a circular knitting machine and thus a rotation of the transport rollers 9 of the information carrier 7.

If desired there may be further connected between line 52 and point 61 another switch 57 upon which acts a second time member 67. The combination from switch 57 and time member 67 have the effect that the line 52 remains connected with point 61 for a preselected period of time when the turn-on and turn-off switch 53 is opened. Time member 67 however does not prevent the immediate closing of switch 57 during the switch-on process.

Line 52, connected with

switches

55 and 57, is also directed with a point 69 which is on a lower potential U when compared to

points

59 and 61.

As seen in FIG. 3, the device operates in the following manner:

Shown above each other is the time curve of the actual values of the lamp voltage U, the lamp current I, the lamp intensity (it and the speed V of the drive device 65. Furthermore, the particular values of U and I are shown here in a broken line. Before a moment t the lamp voltage and the lamp current are at a relatively small value which is determined via the limiting circuit 50 through the potential of point 69. Point 69 is at this time at a potential U which corresponds to the resting state, that is, the standstill of the information carrier 7 and the needle cylinder 1. In this time interval, the rated intensity of lamp 13 cannot be attained in spite of the fact that in the comparison circuit 41 a great difference between the actual intensity and the rated intensity is observed.

The maximum voltage U which is adjusted prior to the moment t can be about 30 percent of the nominal voltage or less. It makes certain that the information carrier will not be damaged with the pertinent intensity of filament temperature of the lamp 13 even in case of longer standstill.

The activation of the turn-on and turn-off switch 51 at moment t causes the maximum voltage to be switched through switch 55 from the value U to a very high value U of point 59. Consequently, the control circuit begins to work due to the absence of any voltage limitation as a result of which the actual intensity of the lamp according to FIG. 3 increases. After a very short turn-on moment, however, the lamp current attains the maximum value I because the lamp resistance during switch-on is relatively small so that shortly after switch-on the limiting circuit 47 becomes effective for the lamp current. Thereafter, the actual intensity of the lamp increases while the current is constant and the lamp voltage rises slowly until it reaches the preselected rated value at time t,. After reaching the rated intensity, the lamp voltage and the lamp current drop due to the action of the control circuit down to relatively small values which are required to maintainthe rated intensity.

The value for U between moments t to t must be so selected that the lamp will under no circumstances be destroyed when these values are attained. In general, it is possible to select the two values between t and t considerably higher than the nominal values without the lamp being damaged even when the switch on process is repeated frequently.

By means of special circumstances, for example, con

tamination, it may happen thatthe lamp intensity does not attain the prescribed rated value even if an output considerably above the rated output is supplied to the lamp beyond moment i One can also visualize a case in which the photoelectric cell 37 is swung put of the area of lamp 113 sothat the control circuit45 cannot operate. In such cases, the lamp 13 would be destroyed at some time after due to overload. To prevent this, time member 54 is so adjusted that after a certain delay which in FIG. 3 corresponds to the time interval between t, and t there will occur a voltage limitation brought about through point 61. For this purpose, point 61 is normally put on a potential U corresponding to the nominal voltage of the lamp, whereas time t is so selected that the lamp 13 at time i, cannot yet be destroyed with certainty if during the time interval t to t it is supplied with an output computed from the possible maximum values U and 1 The switching member 63 which is activated by switching on the turn-on and the turn-off switch 51 may have a differing function which depends on the inertia of the movable parts involved. In the example illustrated, when one is dealing with a circular knitting machine with a relatively heavy needle cylinder 1, the needle cylinder 1 and thus the information carrier 7 are not immediately set in motion during the switch-on of the turn-on and turn-off switch 53. Instead, the movement of these parts begins only after an accidental delay time of about 70 milliseconds which, in FIG. 3, is illustrated through the time interval between t and t and which depends on the inertia of the system, torsion phenomena in the drive means, etc. In such a case, the switching member 63 can simultaneously with the switch-on process also turn on the motor 65 if steps have been taken to make sure that the time interval between t and t within which the rated intensity of lamp I3 is normally attained, is smaller than the time interval between t and 13 Since the time interval t to t in the normal case, is only 30 milliseconds, it is not necessary to provide any additional means for turning on the motor 65.

The switching member 63 may be any switch such as an electronic switch which switches on the machine immediately upon operation of the switch 53 or an electronic switch such as is known in the art.

Except for the case that the motor 65 and the parts connected with it, among other things, also the transport rollers 9 of information carrier 7, can be set in motion within a time interval which is smaller than the time interval between t and t steps must be taken to make sure that the motor 65 will beginto run only with a certain delay. This can. be achieved by associating with the switching member 63 a time member which delays the turn-on of the motor 65 until time t has been reached with certainty. Another possibility, indicated in FIG. 2, consists inactivating the switching member 63 not through the turn-on and turn-off switch 53 but rather to connect it via a line 64 with the output of the comparison circuit 41 so that it will always be activated when the signal, appearing at the output of the comparison switch 41, has the value zero. In this way,- the motor 65 is turned on only when the rated intensity of lamp 13 is attained. v During the turn-off operation, that is, during the opening of the turn-onand turn-off switch 53 at time the rated intensity of thelamp is stillmaintained for a certain delay time which is determined by the timemember 67 up to a time it and only then is the lamp voltage limited in accordance with the voltage U This time delay during the turn-off process is necessary inorder to make sure that the rated intensity will remain-- preserved at least until, in the example selected, the needle cylinder 1 of the circular knitting machine and thus the informationcarrier7 have come to a standstill at t,. The delay time brought about bythe time member its other connection via a resistance 73 to the negative pole 75 of a voltage source. The connection point between the photoresistance 37 and resistance 73 is placed via a diode at the output 79 of the control circuit. During the switch-on process, that is, at time t,,, the photoresistance is only weakly illuminated so that it has a high resistance and so that at output 79 there will be a potential which roughly corresponds to the potential of pole 75.

In case of stronger illumination of photoresistance 37, the potential of the output 79 moves closer and closer to the zero potential. The signal appearing at output 79 is thus proportional to the difference between the actual intensity and the rated intensity of lamp 13 and it can be fed to the adjusting member 33 directly or via amplifiers and the like. 1

For voltage limitation, there may be provided as shown in FIG. 4 a transistor 81 whose base is controlled by the actual value of the lamp voltage, whose collector is located at output 79, and whose emitter is connected to a voltage divider which is located between pole 75 of the voltage source and the ground and which is made up of resistances 83, 85. The dimensioning of this limiting circuit is so selected that the transistor 81 will always be connected through when the actual value of the lamp voltage exceeds a certain value that depends on the emitter voltage of the transistor 81 and thus the signal appearing at output 79 is kept constant, even if the rated intensity has not yet been achieved. The switching to various throughconnection points of the transistor 81, corresponding to the various maximum voltages U U U (see also FIGS. 2 and 3), can be accomplished by means of the correspondingswitches and

resistances

87, 88 which are connected parallel to the resistance 83.

Finally, there may be provided a transistor whose emitter is grounded and whose collector is at output 79. Between output 79 and pole 75 of the voltage source there is the resistance 91. The base of transistor 89 is controlled by a signal analogous to the actual value of the lamp'current. Transistor 89 is always connected through when the actual value of the current exceeds a preselected value, as a result of which the signal at output 79 is kept constant, even if the rated intensity is still not achieved and if therefore a higher lamp output would be required.

The invention is not confined to the examples described here. In particular it is immaterial at what point in the circuit diagram and with whatmeans the voltage and current limitation are accomplished. For example, it would also be possible to bring about a limitation of these values by simulating when the voltage or current boundary is reached an apparent attainment of the rated intensity, that is, upon attainment of the maximum voltage of the maximul current, it vwould be possible to feed the comparison circuit 41 a changed rated value which would cause the difference signal to disappear and which would prevent any further voltage or current increase.

The invention is likewise not confined to circular knitting machines instead, it may advantageously be carried out where ever at the beginning of the information carrier transport full lamp intensity must be achieved and must thereafter be maintained.

The individual switching elements of the control circuit, of the limiting circuits, the time members, and the comparison circuit are known and do not require any further explanation. The same applies to adjusting member 33 which, for example, can be a potentiometer or a power transistor driven by a motor.

Obviously the embodiments shown is exemplary only and a wide variety of embodiments may be devised without departing from the spirit and scope thereof.

What is claimed is:

1. A device for the optical-electrical scanning of an information carrier, said device comprising: a scanning means having at least one lamp for scanning said information carrier; an automatic controlling system for maintaining a desired intensity of said lamp, said controlling system having a photoelectric cell for sensing the actual intensity of said lamp, comparator means for comparing said actual intensity of said lamp with said desired intensity and a controlling means for controlling said lamp so that said actual intensity does correspond to said desired intensity during scanning operations; transport means for establishing relative motion between said information carrier and said lamp for scanning operations; a switching means for switching on and off said lamp and said transport means; a voltage limiting circuit for limiting the lamp voltage, and a first timing element means associated with said voltage limiting circuit for limiting said lamp voltage when switching on said switching means at first to a value above a preselected rated voltage and a preselected time interval after said switch-on process to said rated lamp voltage.

2. The device according to claim 1, including a second timing element associated with said voltage limiting circuit for maintaining said desired intensity of said lamp a preselected time interval afer switching off said switching means.

3. The device according to claim 2, wherein said voltage limiting means includes means for limiting said lamp voltage-to a resting voltage after a delay determined by said second timing element whereby said resting voltage corresponds to the voltage when the information carrier is at a standstill.

4. The device according to claim 1, including a current limiting circuit associated with said lamp, said circuit acting when said information carrier is at a standstill and during scanning operations.

5. The device according to claim 1 including means coupled with said switchingmeans for automatically switching on said transport means after attainment of said desired lamp voltage.v

6.The device according to claim 5, wherein said means for automatically switching on said transport means is controlled by said comparator means.

Claims

3. The device according to claim 2, wherein said voltage limiting means includes means for limiting said lamp voltage to a resting voltage after a delay determined by said second timing element whereby said resting voltage corresponds to the voltage when the information carrier is at a standstill.

5. The device according to claim 1 including means coupled with said switching means for autoMatically switching on said transport means after attainment of said desired lamp voltage.

6. The device according to claim 5, wherein said means for automatically switching on said transport means is controlled by said comparator means.