DE2041795C - Device for optical-electrical scanning of an information carrier - Google Patents

Description

Another possibility for avoiding the above-mentioned predetermined target intensity of the lamps and the disadvantage is to switch off the lamps at each of a limitation circuit for the lamp voltage, standstill of the information carrier relative to the scanning, marked by a voltage direction. However, this has the also voltage limiting circuit (50) associated with the disadvantageous consequence that the lamps at the re-element (54), through which the lamp voltage is switched on, are not immediately ready for operation because their target intensity is not immediately set when switched on, but rather in Dependence on the dimensions of the filament lent above the nominal voltage is only reached after a (U "αϊ) and a preselected period of time after a certain delay time of, for example, 500 MiHi switch-on process to the nominal voltage (Us) » ° seconds and consequently with the is limited, and has to be serviced by a device (63) coupled to the on-off scanning process until the expiry of this time interval switch (53). This is particularly noticeable when the transport device is switched on automatically when the information carrier device (21) has reached the target value. to control the functionality of a machine,

2. Apparatus according to claim i, characterized in that there are »5 ζ. B. a knitting machine, is used and indicates that a further timing element (67) is provided to the machine, a pushbutton switch is provided by maintaining the target intensity when switching off the machine in crawling gear operated process is provided. can be used to control certain control processes

3. Device according to claim 2, thereby trolling. In this case it would have to indicate that the lamp (13) after the delay on starting the machine determined by switching on the information carrier transport and before the timer (67) first switches over the mentioned open-circuit voltage (Uh) . Waited for a delay time of around 500 milliseconds

4. Device according to one dt claims 1 to 3, are due to incorrect switching of the machine characterized in that the device (63) of the not yet reached target intensity of the lamps by avoiding the setpoint and actual intensity of the lamp (13) 35. Such delays for everyone comparative comparison circuit (41) controlled actuation of the pushbutton switch are for the operator control. person unreasonable even if they are through

5. Device according to one of claims 1 to 4, brought about an automatically acting timer characterized in that the lamp (13) will be on, because the pushbutton switch in the setting, Continuously effective current limiting circuit (47) 40 Maintenance or repair of the machine very frequently assigned. must be operated.

The invention is therefore based on the object

a device of the type mentioned

create, on the one hand, excessive heating

45 of the information carrier automatically avoided and

on the other hand, the fastest possible start of the scanning

There are already devices for the optical-electrical process is made possible.

see scanning of an information carrier known, the invention is da / u characterized by a dem

the timing element associated with a voltage limiting circuit consisting of lamps and photocells, Scanning device, a transport device for 50 through which the lamp voltage is produced during switch-on a relative movement between the information process initially on a substantially above the nominal value carrier and sampling device, an on-off voltage lying value and a preselected time switch for the lamps and the transport device, stretch to the denominators after the switch-on process Control circuit for maintaining a bias voltage is limited, and by one with the dialable Target intensity of the lamps and a device coupled to the automatic limiting circuit equipped for the lamp voltage see switching on the transport device are and serve the information carrier with reaching the target intensity.

constant intensity to expose and the scanning by the fact that the lamps when switching on device to switch off automatically if the lamp voltage exceeds the normal operating data a preselected maximum value of 60 going electrical power is supplied, results achieved. the main advantage that its target intensity

A disadvantage of devices of this type exists in a very short time, for example within in that the lamps in addition to the exposure also a 50 instead of 500 milliseconds is achieved. the considerable heating of the information carrier causes subsequent limitation of the lamp voltage ken. Particularly in the case of a longer standstill or at 65 the nominal voltage brings the further essential a relatively slow step-by-step advantage with it that the lamps despite initial Transport of the information carrier relative to the scanning overload even then not be destroyed facility can increase the temperature so much if the target intensity is due to some-

which does not reach faults, or does reach them, but is not displayed.

Due to the device for automatically switching on the transport device, the operator needs do not perform two switching operations, because the machine without further delays is switched on immediately when the target intensity is reached. Will the invention work on machines like for example knitting machines are used whose drive or working elements, e.g. B. the needle cylinder, start to work only after a delay time caused by inertia effects that is greater than that is the time interval required to reach the target intensity, then there is the device for automatic Switching on the transport device simply by means of the transport device when actuated switch on directly using the on / off switch. On the other hand, if the inertia effects are very small, then this can Device in a further development of the invention by means of a device which compares the setpoint and actual intensity of the lamps Comparison circuit can be controlled.

In order to ensure that the information carrier comes to a complete standstill even during the switch-off process is properly sampled, is in a preferred embodiment of the invention, a further timing element for Maintaining the target intensity provided during the switch-off process. Finally, it is useful the lamps do not switch to "zero" voltage after the delay determined by the additional timer, but to switch to an open-circuit voltage that is not dangerous for the information carrier, because this results in it an even faster achievement of the target intensity during the switch-on process is made possible.

The invention is described below in conjunction with the drawing using an exemplary embodiment.

F i g. 1 schematically shows an optical-electrical scanning device for controlling a circular knitting machine suitable information carrier;

F i g. 2 schematically shows an embodiment according to the invention Circuit arrangement for operating the lamp and the transport device for the information carrier;

F i g. 3 shows schematically the time course of the intensity, the current and the voltage of the lamp the scanning device;

F i g. 4 shows an exemplary embodiment for the control circuit and the limiting circuits of the circuit arrangement.

In Fig. 1 is shown schematically the needle cylinder 1 of a circular knitting machine rotatable in the direction of arrow P , the cylinder needles 3 of which can be selected in a known manner by star magnet systems 5 by supplying them with electrical control signals. The control signals are obtained by scanning an information carrier 7 which is transported past a scanning device 11 by means of transport rollers 9. The information carrier is, for example, a film strip with opaque and translucent markings. The scanning device 11 includes at least one lamp 13, e.g. B. an incandescent lamp, and at least one invisible photocell.

A transport device 21 in the form of a stepper motor is used to drive the transport / trolleys 9, which is connected to a clock pulse generator 29, which when the needle cylinder rotates per passing Cylindernadti generates a clock signal through which the information carrier 7 by one Step is further transported. Needle cylinder ι and Information carriers 7 thus rotate synchronously with one another. Such a synchronous movement can can also be generated by other means, for example in that the drive shaft of the Needle cylinder motor is connected to the transport rollers 9 via a gear or the like. According to FIG. 2, the lamp 13 is connected to a battery 35 via a resistor 31 and an actuator 33.

By means of the actuator 33, the lamp 13 supplied can Power can be set to any value. A photo sensor 37 is used for detection the actual intensity of the lamp 13 and emits an electrical signal proportional to the intensity,

X5 that via an amplifier 39 of a comparison circuit 41 is supplied, in which it is proportional to a preselected target intensity signal that is supplied via a line 43, is compared. The difference between the I intensity and the

Signals proportional to the setpoint intensity are fed to a control circuit 45, which has a emits an amplified difference signal which is fed to the actuator 33. In dependence of The actuator 33 becomes the size of the differential signal

»5 in the sense of direction and adjusted until the The difference signal disappears or the lamp 13 has reached the desired target intensity.

A current limiting circuit 47 is used to limit the lamp current

Current flowing is measured at resistor 31, and the measurement signal obtained is fed to current limiting circuit 47. A signal which represents a maximum permissible lamp current I _{max is} fed to a further input of the current limiting circuit 47 via a line 49. As long as the actual value of the lamp current is below the value / _m az , the current limiting circuit 47 has no influence on the rest of the circuit arrangement.

However, in the event that the actual value of the lamp current exceeds the value I _max , the current limiting circuit 47 emits a signal which actuates a switching element in the control circuit 45 in such a way that the difference signal emitted by the control circuit 45 remains limited to the current value. This has the consequence that the actuator 33 remains in its current position and the lamp current constantly maintains the value Imax , even if the intensity of the lamp has not yet been reached and therefore the difference between that of the Sr> supplied to the input of the control circuit 45 llii, iensität proportional signals is and remains relatively large.

The voltage applied to the lamp 13 is limited by a voltage limiting circuit 50. The voltage limiting ski 50 is supplied on the one hand with the signals proportional to the actual voltage and on the other hand via a line 52 with signals that are related to a preselected maximum lamp voltage U _max . In the event that the actual voltage of the lamp 13 is greater than U _ma x , the voltage limiting circuit 50 emits a signal which is fed to the control circuit 45 and causes the difference signal appearing at the output of the control circuit 45 regardless of the current actual intensity the lamp remains constant as long as the actual voltage of the lamp 13 is greater than U _n

is.

According to a preferred embodiment

the maximum lamp voltage Umax "be selected differently. For this purpose, an on-off switch 53 is provided which is connected via a timer 54 to a switch 55 '. The switch 55 is on the one hand to the lead 52 and on the other hand to a point 59 The line 52 can also be directly connected to a point 61. The point 59 is at a relatively high potential Un, whereas the point 61 is at a relatively low potential Un Closing the on-off switch 53 is also closed, but is reopened after a certain time delay.As a result, immediately after the switch-on process, the line 52 is initially at a relatively high and then at a relatively low potential.

With the on-off switch 53 is also a device 63 for automatically switching on the Transport device 21 connected. In the example shown, the device 63 acts directly on one Motor 65, the one rotation of the needle cylinder 1 of the circular knitting machine and thus one rotation of the Transport rollers 9 of the information carrier 7 brings about.

In an expedient development, there is another switch 57 between line 52 and point 61 switched, on which a second timing element 67 acts. The combination of switch 57 and element 67 has the effect that the line 52 when the on-off switch 53 is opened for a preselected period of time remains connected to point 61. However, the timer 67 does not prevent immediate closure of switch 57 during the switch-on process.

The line 52 connected to the switches 55 and 57 is finally also directly connected to a point 69 which is at a lower potential Ur compared to the points 59 and 61.

The mode of operation of the device described is illustrated below with reference to FIGS. 3 described:

In Fig. 3 shows the time course of the actual values of the lamp voltage U, the lamp current /, the lamp intensity Φ and the speed V of the transport device 21 one above the other. In addition, the respective values of U _max and I _{max are shown in} dashed lines. Before a point in time / ₀ , the lamp voltage and the lamp current are at a relatively small value, which is determined via the voltage limiting circuit 50 by the point 69 with the potential Un , which corresponds to the idle state, ie the state of the information carrier 7 and the needle cylinder 1. In this period of time, the target intensity of the lamp 13 cannot be achieved in spite of the fact that the difference between the actual intensity and the target intensity is large.

The maximum voltage Un set before time I ₀ can be approximately 30% of the nominal voltage or less. It ensures that the information carrier is not damaged at the associated intensity or filament temperature of the lamp 13, even if it is not used for a long time.

When the on-off switch 53 is actuated at the point in time I ₀ , the maximum voltage is switched over by the switch 55 from the value Ur to a very high value Un at point 59. The consequence of this is that the control circuit 45 begins to work, whereby the integrity of the lamp according to FIG. 3 increases. After a very short switch-on moment, however, the lamp current reaches the maximum value Imax, because the lamp resistance is relatively small when switched on, so that the current limiting circuit 47 becomes effective shortly after switching on. In the following, the actual intensity of the lamp increases with constant current and slowly increasing lamp voltage until it reaches the preselected target value at the time /. After reaching the target intensity, the lamp voltage and the lamp current decrease

ίο Reason for the effect of the control loop except for relative small values that are required to maintain the target intensity.

The values for U and _maz l _m ax between times ₀ and I / are selected so that the lamp can be destroyed by no means to achieve these values. In general, it is possible _{to choose these two values between / 0} and /, even if the switch-on process is repeated frequently, significantly higher than the nominal values.

ao Due to special circumstances, e.g. B. pollution, the case may arise that the lamp intensity does not reach the prescribed target value even if the lamp is supplied with a power significantly above the rated power beyond the time I _x. It is also conceivable that the photosensor 37 is pivoted out of the area of the lamp 13 so that the control circuit 45 cannot function. In such cases, the lamp 13 would at any past /, lying time

point can be destroyed as a result of permanent overload. In order to avoid this, the timer 54 is set so that after a certain delay time, which is shown in FIG. 3 corresponds to the time interval between / ₀ and I ₂ , a voltage limitation caused by point 61 occurs. For this purpose, point 61 is normally set to a potential Un corresponding to the nominal voltage of the lamp, whereas time I ₂ is selected so that lamp 13 is definitely not destroyed at time I ₂ even if it is in the time interval / ₀ to t ₂ the power calculated from U _ma z and Imax is supplied.

The device 63 actuated by the switching on of the on-off switch 51 can have a different function depending on the inertia of the movable parts involved. In the illustrated embodiment, which is a circular knitting machine with a relatively heavy needle cylinder 1, the needle cylinder 1 and thus the information carrier 7 are not set in motion immediately when the on / off switch 53 is switched on, but the movement is stopped Parts only begins after a random delay time of about 70 milliseconds, which is shown in FIG. 3 is represented by the time interval between / „and / ₃ and depends on the inertia of the system, torsion phenomena of the drive means, etc. In such a case, the device 63 can switch on the motor 65 at the same time as the switch-on process, if it is only ensured that the time interval between I ₀ and / ", within which the nominal intensity of the lamp 13 is normally reached, is smaller than the time interval between / "And I is ₃ . Since the time interval I ₀ to / is normally only 30 milliseconds, no additional means for switching on the motor 65 need be provided.

However, in the event that the motor 65 and the related parts, including the transport rollers 9 of the information carrier 7, within a tent interval can be set in motion,

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that is smaller than the time interval between Λ, and /, it must be ensured that the motor 65 only begins to run with a certain delay. this can be achieved in that the device 63 is assigned a timer, which the activation of the motor 65 is delayed until the point in time / is reached with certainty. Another Opportunity that is shown in FIG. 2 is indicated, consists therein, the device 63 not through the on-off switch 53, but through the comparison circuit 41 to be controlled so that it is always actuated when the appearing at the output of the comparison circuit 41 Signal has the value zero or the target intensity of the lamp 13 has been reached.

During the switch-off process, ie when the on-off switch 53 is opened at time t _t , the nominal intensity of the lamp is maintained for a certain delay time, which is determined by the timer 67, up to a point in time / ", and only then is it limited the lamp voltage corresponding to the voltage U _n instead. This time delay in the switch-off process is necessary to ensure that the setpoint intensity is maintained at least until the needle cylinder 1 and the information carrier 7 have come to a standstill at t _{6 in the selected exemplary embodiment.} The delay time brought about by the timing element 67 thus depends on the inertia J. / movable parts which are important for the scanning of the information carrier 7 during the switch-off VO gear.

in Fig. 4 shows a special exemplary embodiment for the control circuit and the two limiting circuits, the same reference numerals being used to identify the same parts as in FIG. 2 are used. The photo sensor 37, which has one connection to ground and is designed as a photoresistor, is connected with its other connection via a resistor 73 to the negative pole 75 of a voltage source. The connection point between photosensor 37 and resistor 73 is connected to output 79 of the control circuit via a diode. During the switch-on process, ie at time / ₀ , the photosensor is only weakly illuminated, so that it has a high resistance and a potential is present at output 79 which corresponds approximately to the potential of pole 75.

With stronger exposure of the photosensor 37, the potential of the output 79 approaches more and more Zero potential. The signal appearing at output 79 is therefore the difference between the actual intensity and the target intensity of the lamp 13 proportional and can be directly or via amplifiers and the like Actuator 33 are supplied.

For voltage limitation in F · "e Λ, a transistor 81 is provided, the base of which is controlled by" ien actual value of the lamp voltage, the koi lecturer at the output 79 and its emitter connected to a lying between the pole 75 of the Spannimgsquelle and ground, resistors 83, 85. The dimensioning of this limiting circuit is chosen such that the transistor 81 is always switched through when the actual value of the lamp voltage exceeds a certain value dependent on the emitter voltage of the transistor dl Signal kept constant, even if the target intensity has not yet been reached. Switching to different switching points of transistor 81 according to the different maximum voltages Un, Ux, Un (cf. which are connected in parallel to the resistor 83.

Finally, a transistor 89 is also provided, its emitter to ground and its collector to

ao exit 79 is located. A resistor 91 is provided between the output 79 and the pole 75 of the voltage source. The base of the transistor 89 is determined by the actual value of the lamp sirom? analog signal controlled. The transistor 89 is then always through-

»5 switched when the actual value of the current is a preselected one Value, whereby the signal at output 79 is kept constant, even if the The target dimension has not yet been reached and a higher lamp output would therefore be required per se.

The invention is not limited to the exemplary embodiments described limited, in particular it does not matter at which point of the circuit arrangement and the means by which the voltage and current are limited. Example wisely, it would also be possible to limit these values in that when they are reached the voltage or current limit is simulated that the target intensity has been reached, d. h .. at When the maximum voltage or the maximum current is reached, the comparison circuit 41 could be changed Setpoint are supplied, which makes the difference signal disappear and another voltage or Current increase prevented.

The invention is not limited to circular knitting machines either, but can be used anywhere Use advantage where the full lamp intensity is reached at the beginning of the information carrier transport must be and then be maintained.

The individual switching elements of the control loop, the

so limiting circuits of the timing elements and the comparison circuit are the ⁿ Achmann known and require no further explanation. The same applies to the actuator 33, which is, for example, a potentiometer operated by a motor or a power transmission

sistor can be.

For this purpose 2 sheets of drawings

'209652/389

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Claims (1)

Damage or permanent deformation of the patent claims: information carriers lead to the fact that multiple use of the same is impossible. 1. Device for opto-electrical scanning To avoid this disadvantage could to the stung an information carrier with one of Lam- 5 purpose, a certain proportion of the not for scanning pen and photocells existing scanning devices to sort out the required ultrared radiation from the lamps, a transport device for the production of beer, heat filters are provided. Do this a relative movement between information- in general, however, such a strong increase in carrier and scanning device, an on-off lamp power required that the life of the Switch for the lamps and the transport of the lamps is noticeably reduced.