KR100364334B1 - Device for optically measuring the angular velocity of an object - Google Patents

Abstract

PURPOSE: To provide an improved device for optically measuring the angular velocity of a rotating object. CONSTITUTION: This device is equipped with a first disk 23 having a light interruption part 24 with a pattern of rotational symmetry, and working in cooperation with an object, a second disk 29 having the same pattern, and a detector 34 for receiving light transmitted through the pattern and converting the light into an electrical signal. This device has very high accuracy, high reliability and a compact form. Also, the linear velocity of a long object such as a recording tape can be measured by use of the device.

Description

Device for optically measuring the angular velocity of an object

The present invention relates to an apparatus for optically measuring the angular velocity of a rotating object, the apparatus comprising: a rotatable first disk driven by a rotating object, a second disk and an illumination system for illuminating the entire pattern simultaneously; And a detection system, said first and second disks having elongated interruptions in a pattern that is periodic and rotationally symmetrical to the disk surface.

The invention also relates to a device of this type, which is adapted to measure the linear velocity of elongated objects.

The present invention further provides the speed of two reels used as feed reel and winding reel, a scanning head arranged in a path covered by tape between the two reels, and a tape speed sensor and a reel motor functioning as a reel. A capstanless tape scanning apparatus having a tape speed control loop including a control circuit for controlling.

Optical angular velocity measuring devices are known from US Pat. No. 4,658,132.

Capstanless tape scanning devices are known in various embodiments and are described in particular in British Patent 1,330,923 and US Patent 3,809,335. As can be seen from the British patent specification, the use of a capstan in combination with a pressurizing mechanism to drive the tape at a constant linear velocity has the advantage that precise control of the tape speed can be realized at minimal cost as far as control of itself is concerned. Has However, when capstans are used, a number of drawbacks occur, three of which are described in the British patent specification, the complex mechanism for introducing cassettes, the difficulty of guiding tape edges, and the risk of greater tape damage. Moreover, there is a problem of contamination and sleeping tape.

The above drawbacks and problems can be avoided by driving the tape in a different way than with the aid of the capstan, ie by means of the supply reel and the winding reel. In this case, provision should be made to maintain the tape speed at the position of the scanning head.

A possible preparation mentioned in British Patent No. 1,330,923 is the use of a tape driven tachometer which is not further described and considered to be less suitable. In the British patent, one choice is made for a system in which one of the reels is driven with a control signal and a nonlinear signal superimposed thereon and inversely proportional to the tape diameter on the equivalent reel. In a capstanless tape scanning apparatus in which the tape speed is controlled by the drive mechanism of the winding reel, slip coupling is present in this drive mechanism, and this slip coupling causes energy loss. U. S. Patent No. 3,809, 335 describes a tape drive in which a feed reel and a winding reel are driven and tape tension as well as acceleration, deceleration, and speed are measured. The device does not include a separate tape speed measurement station.

Since the scanning head of the tape player is at a certain distance from both the feed reel and the winding reel, it is preferable to use a separate speed measuring station arranged adjacent to the scanning head so that the speed is measured at a constant position. The signal of the speed measuring station may alternatively be used as time base correction when processing the information signal read from the tape. Optical measuring devices are preferred for their use because they are inexpensive and compact by current technology and have high resolution and large measurement accuracy. Compared with the magnetic angular velocity sensor, the optical sensor has the advantage that the quality of the measured output signal is less dependent on the range of rotational frequency at which the measurement is made and less sensitive to the electrical interface. In a magnetic sensor, interference may occur between the magnet and the bearing.

Optical angular velocity measuring devices intended to measure the angular speed of a motor, disclosed in US Pat. No. 4,658,132, may be considered for use in tape speed measuring stations. The device described in U.S. Patent No. 4,658,132 has a first disk which rotates with a motor shaft and the disk stop in the form of an optical transmission slit is arranged in a ring form, and a plurality of radiation reaction detection elements are also arranged in a ring form. A second fixed disk, wherein the number of detection elements matches the number of slits of the rotating disk. This disk is illuminated and the radiation passing through the slit is received by the detection element. When the motor is rotated, the slit is displaced relative to the detection element so that the maximum and minimum amounts of radiation are alternately received by the detection element. The sum of the output signals of these elements is a periodic signal whose frequency represents the slotted disk, ie the angular velocity of the motor.

German patent application no. Describe the sensor.

It is an object of the present invention to provide a novel optical angular velocity measuring device, in which a high resolution with various advantages and better use of available radiation are the most important advantages compared to US Pat. No. 4,658,132. The apparatus according to the invention comprises an illumination system comprising a radiation source in the form of a diode and a radiation guide which aggregates this radiation into a beam whose cross section is suitable for the cross section of the pattern, the detection system passing through two patterns from the illumination system. And a radiation detector for receiving the emitted radiation and condensing it into a beam having a circular cross section, and a signal detector for converting the intensity change of the beam into an electrical signal.

The radiation source diode is a light emitting diode (LED) or semiconductor laser. The signal detector is a conventional photodiode.

Each speed sensor is made of conventional and very small and inexpensive devices.

Currently, resolution is determined by the number of breaks in both disks. Very narrow interruptions, i.e. a large number of interruptions, can be provided on the disc with the current technology. In the apparatus described in US Pat. No. 4,658,132, the accuracy is limited because the detection element and the strips between these elements must have a relatively wide width such that the number of detection elements that can be provided on the stationary disk is limited.

According to the invention, since the disks are illuminated with a beam having a uniform intensity distribution, greater accuracy is achieved.

According to the invention, the device for measuring the absolute value of the angular velocity is characterized in that the second disk is arranged to stop.

However, the device according to the invention is characterized in that the second disk is driven at a constant angular velocity. The angular velocity can be measured relative to the reference velocity. For example, this device may be used in devices where only angular velocities are constant and equal to the reference value.

The apparatus comprises one of the patterns divided into stops of the first and second periodic, rotationally symmetric sub-patterns having the same period, and the location of the stop of the second sub-pattern at the location of the stop of the first sub-pattern. It may be offset by a distance equal to or more than one quarter of the sub pattern period, and a second detector may be provided for receiving radiation passing through the second sub pattern and the pattern of the other disk.

The measuring device makes it possible not only to determine the angular velocity or the magnitude of the deviation between this angular velocity and the reference velocity, but also to determine the direction of the deviation or rotation relative to the reference velocity.

There are two types of embodiments of the device according to the invention.

The first embodiment is a round radiation guide disc, one of which is provided with a stop pattern at its outer edge, and the other disc is an annular radiation guide disc arranged around the other disc and provided with a stop pattern at its inner edge. It is characterized by.

A first preferred embodiment is characterized in that the illumination system consists of an annular disk and a radiation source positioned opposite the outer side of the disk, wherein the round disk has a conical reflector and forms part of the radiation collection system.

Since the disk not only functions as a carrier for the pattern of the interruptions, but also forms part of the illumination system that must supply a radiation beam of uniform intensity distribution and forms part of the collection system, the number of elements of the device can remain limited. have.

In a first preferred embodiment, the protruding edge of a radiation guide disk having an annular disk having a U-shaped cross section and having a conical reflector therein, while one disk surface supports the radiation source and the other disk surface supports the detector. And the round disk is provided with a reflector.

This embodiment yields a better pattern of uniform illumination than the first embodiment.

The second embodiment is a round disk in which the first and second disks are arranged to face each other, and has a common characteristic feature that the pattern of the stops on these disks is an annular pattern.

The second preferred embodiment is that two disks, one of which forms part of the illumination system and the other of which forms part of the collection system, are radiation guide disks, the radiation being trapped in the disks due to the total internal reflection, while the radiation Can exit from the radiation system, ie the disc associated with the break pattern in the disc, and the radiation can enter the collection system, ie the disc associated with the break pattern in the disc. The advantage of this embodiment is that again the number of elements of the device may remain limited.

The first and second embodiments may be characterized in that the stops consist of deformations on the smooth disk surface.

Preferred uses are made from the fact that the radiation remains trapped within the disc when the complete internal reflection leaves the disc at a location where a surface smoothness occurs that is completely smooth. The deformation part may be composed of a groove part which can be provided easily and accurately by scratching.

The first and second embodiments may alternatively be characterized in that the stops consist of transparent slits on the opaque disk surface.

Such slits can be provided inexpensively and accurately by means of photolithographic and replication techniques.

The first and second embodiments may be characterized in that at least one disk is made of a transparent composite material. Synthetic materials, for example polymethylmethacrylate (PMMA), not only have transparent properties but also have the advantage of being inexpensive and easily shaped by molding means.

The second embodiment consists of slits in which the disks are opaque and the interruption is in these disks, the lighting system having an inner radius above and an outer radius with respect to the radius of the slit of the annular pattern of the first and second disks. Characterized in that it is suitable for supplying a beam having an annular cross section below.

The discs with slits, which are hereafter described as slotted discs, can be made in a simple and inexpensive manner such as copying from a mask disc. If the radius of the annular beam cross section, or the radius of the illumination ring is equal to the radius of the annular slit structure or the slotted ring, or there is no loss of measuring radiation, no false radiation is generated and the slotted ring is not fully illuminated, Inaccuracy reaches the mean by the slit and has no effect on the measurement.

If some tolerance is employed for mutual positioning of the slotted ring and the illumination ring, it is desirable to make the width of the illumination ring smaller than the width of the slotted ring.

However, it is alternatively possible to make the width of the illumination ring larger than the width of the slotted ring to obtain the required position tolerance.

The summary of Japanese Patent Application No. 61-228310 describes each position sensor rather than a speed sensor in which an annular illumination beam is used.

However, the rotating disk of this sensor has only one slit so that the available irradiation cannot be used effectively, and the measurement result depends on the inaccuracy of the slit.

An embodiment of the device according to the invention in which the irradiation is efficiently directed to a rotatable slotted disk to realize an annular uniform illumination, the illumination system is rotated with a radiation source, a first radiation guide, and an inclined reflective edge And a rotary radiation guide disk arranged adjacent to and parallel to the sex guide.

The first radiation guidance ensures that all source radiation coupled to it remains available for measurement, providing the possibility of a compact design illumination system. Due to its rotational symmetry, the rotatable radiation guide disc ensures uniformity of radiation, and the inclined edge ensures that the radiation spot on the slotted disc is annular.

An embodiment of the apparatus in which the radiation passed through the slotted disk is collected as efficiently as possible with a beam suitable for feeding to the detector comprises a second radiation guide disk having an inclined reflective edge and arranged at a side away from the rotatable slotted disk. While a complete detection system is included, the conical reflector is arranged centrally in the second guiding disc.

The inclined edge of the second radiation guide disk converts the annular irradiation spot formed therein into a fan of subbeams towards the center of the disk, with the central cone reflecting this subbeam as one beam having a circular cross section. do.

This embodiment is characterized in that at least one of the two radiation guide discs is made of a transparent synthetic material. This composite material may be PMMA.

Embodiments in which two slotted disks are used are preferably characterized in that a second radiation guide for guiding radiation from the conical reflector is arranged between the second radiation guide disk and the detector.

An embodiment of the present invention which has an advantage from a structural point of view, wherein the irradiation source, the first irradiation guide, the second irradiation guiding disc, the second irradiation guide and the detector are arranged in a U shape, and a part of the first irradiation guide is U-shaped. And a hollow tube for accommodating the central portion and accommodating the rotating shaft.

This shaft is fixedly connected to the object and thus rotates with the object. However, the shaft may alternatively be a stationary axis, in which the object may rotate about the axis.

The last mentioned embodiment offers the possibility of integrating the source in the form of an LED and a detector, for example on a support, consequently limiting the number of parts to be located separately.

Embodiments of the above-mentioned device may be characterized as a friction roll driven by an elongated object in which a rotating object moves to convert the device into a linear velocity measuring device.

In this way, the field of application of the measuring device can be extended to the professional and consumer domain where linear velocity must be measured with high accuracy.

The present invention relates to two reels used as feed reels and winding reels, one or more scanning heads arranged in a path covered by tape between the two reels, and a tape speed sensor and a reel functioning as a winding reel. A tape scanning apparatus is provided with a tape speed control loop including a control circuit for controlling. The device is characterized in that the tape speed sensor is the linear speed measuring device described above.

The speed sensor according to the present invention is remarkably suitable for this purpose because the tape speed sensor in such a consuming device must not only be cheap and small but also accurate and reliable.

A reproduction head for reproducing the information signal recorded on the tape, a buffer memory having an input portion coupled to an output portion of the reproduction head and an output portion coupled to an output terminal for supplying the information signal, and a recording clock signal input portion of the buffer memory; First clock signal generator means for generating and supplying a first clock signal having a first clock frequency at an output coupled to the second clock signal; and a second having a second clock frequency at an output coupled to a read clock signal input of the buffer memory. A second clock signal generator means for generating and supplying a clock signal, and a detection means for determining a filling level of the buffer memory and supplying a control signal at the output to measure a filling level of the buffer memory, the buffer memory Is suitable for storing the information signal in response to the first clock signal, and the buffer memory at the output section in response to the second clock signal. This type of scanning device is suitable for supplying a stored information signal, wherein one of the first or second clock signal generators is suitable for generating a clock signal having a fixed clock frequency. Coupled to an input of another of the signal generator means, the other clock signal generator means inducing a clock signal having a clock frequency in accordance with the electrical signal of the apparatus, the output of the detection means being of a control circuit for controlling the speed of the winding reel It is characterized in that coupled to the input unit.

In such a tape scanning apparatus, the buffer memory performs time base correction on a signal read from the tape by the reproduction head. Moreover, the filling level of the buffer memory is used to control the tape speed. In particular, when a device with a friction roll according to the present invention is used, a very satisfactory control can be realized so that it is possible to even reproduce an analog compact cassette in hi-fi quality.

In this regard, it is known from the "Research Disclosure" page 805/6 of December 1993 to realize a combined time base correction and tape speed control when reading audio signals with a tape scanning device. Therefore, known combined time base correction and tape speed control seem to work less satisfactorily. However, the device using the friction roll according to the present invention has a large resolution and the use of such a device in a tape scanning device is accurate and sure to lead to a satisfactory realization of combined control.

These features of the present invention will become apparent with reference to the embodiments described later.

1 shows parts of a tape scanning apparatus which is equivalent to understanding the invention. The apparatus may comprise a plurality of scanning elements and for example have a scanning head 1 which can read or remove audio or video information from the magnetic tape 2 contained in the cassette 3 or write to the tape. .

The scanning head is coupled to a known electronic circuit part 5 via an electrical connection 4. This circuit comprises an amplifier and decoding circuitry 6 for the read signal coupled to the loudspeaker 7 which makes it possible to hear the read audio signal in the case of an audio tape scanning device. The audio tape scanning device is of SDAT type or DCC type, the details of which are described in EP application No. 0,504,973.

The apparatus further comprises tape conveying means in the form of reels 8, 9 driven by the motors 10, 11 and the motor control circuit 16. In operation, the tape is conveyed from feed reel 8 to guide reel 9 via guide rolls 13 and 14.

The tape can be analog video or tape as well as digital video or audio tape, and the present invention is particularly advantageously used in the latter case and in tape scanning devices where disturbances, commonly referred to as jitter, occur.

Moreover, the tape may be an optical tape that may contain audio or video programs or data as well as magnetic tape.

In the case of an optical tape, the device does not have a magnetic scanning head, but has an optical scanning head that includes one or more scanning elements. The tape may alternatively be a magneto-optical tape, where the spot is used to record and read information when the scanning head has not only a magnetic coil but also optical means for forming a scanning spot at the position of the magnetic coil.

According to the invention, all the above mentioned devices are equipped with a tape speed measuring device comprising a friction roll driven by a tape. For the sake of clarity, only the friction roll 21 of the tape speed measuring device is shown in FIG. As schematically shown by the connecting means 13 in FIG. 1, the output signal of this measuring device is applied to the control circuit 16 for the reel motors 10, 11 so that the rotational speed of the motor is adjusted to the scanning head 1. It can be applied to the tape speed measured at a position adjacent to, and therefore the tape speed can be kept constant at this head, while the circuit 16 controls one of the motors 10, 11 at a given moment, The associated reel functions as a winding reel. Depending on the tape running direction, the two reels function as winding reel or feed reel.

The principle of the angular velocity measuring device according to the invention is described with reference to an embodiment using a slotted disk, which is shown in FIG. This embodiment comprises an opaque disc 23 with a large number of slits 24 as shown in FIG. All slits, shown only partially in FIG. 3, are arranged in the form of a ring 25 having an inner radius r and an outer radius R. FIG.

In operation, the disk rotates at the same speed as the object whose angular velocity has to be measured. For this purpose, the disk is fixed to the roll 35. This roll may be the object itself if the object is a friction roll.

The roll is rotated about the shaft 28 by means for clamping the roll and journal-supporting the roll. The object may also be arranged at a distance from the slotted disk 23. In this case, the shaft 28 is a drive shaft connected to the object. The shaft 28 may be a fixed shaft around which the roll rotates.

A second opaque disk 29, in which a large number of slits arranged in a ring is also arranged, is arranged facing the slotted disk 23. The second slotted disk 29 may be the same as the first slotted disk 23, which has advantages in manufacturing technology.

The second slotted disk is fixed. The radiation guide plate 30 with the inclined edge 31 is arranged at the center. A radiation exit gap 33 is located opposite this reflector, and a radiation-sensitive detector 34 is arranged behind the gap.

The first slotted disk is radiated from the top, and the irradiation passing through the slit 24 is incident on the second slotted disk 29 through which the slit passes radiation to the guide plate 30. In this plate, radiation is directed towards the reflector 32 and reflected through the gap 33 to the detector 34.

In the initial position of the slotted disk 23, the slit 24 is positioned opposite the opaque portion 26 of the slotted disk 29, with a minimum amount of radiation passing through the guide plate 26. When the disc 23 is rotated, the slit overlaps with the slit of the disc 29 in increasing range.

When the whole overlaps, the radiation amount passing through the radiation guide plate 30 is the maximum, and the output signal So of the detector 34 has the maximum value.

As the disk 23 is further rotated, the amount of radiation passed again decreases to the minimum level and continuously increases to the maximum amount again.

When the disk 23 is rotated continuously, and therefore when the object is rotated, the output signal So has a periodic sinusoidal change. The instantaneous periodic frequency of this signal is proportional to the instantaneous angular velocity of the object.

If the radiation to be measured has a uniform intensity distribution, the rotation of the slotted disk 23 relative to the slotted disk 29 will be followed by the same local intensity change for each slit.

Annular illumination is preferably used so that the available radiation is used as efficiently as possible. The inner and outer radii of the illumination ring, schematically illustrated by block 36 in FIG. 2, are the same as the inner and outer radii of the rings on the slotted disks 23, 29, so that there is no loss of radiation and the rings radiate completely. do. Moreover, it is a minimum risk that the radiation from the illumination ring can be interference radiation to the detector. If a certain tolerance is allowed in the mutual positioning of the slot ring and the illumination ring, it is desirable to make the width of the illumination ring smaller than the width of the slot ring. Alternatively, it is possible to make the width of the illumination ring larger than the width of the slot ring to obtain the required position tolerance. The illumination ring may be fixed or moved together with the roll 35 as schematically shown by the connection 37 in FIG. 2. The illumination ring is in the form of a lamp bent into a ring, but is preferably realized in the form shown in Figures 5, 6 and 6b. The radiation guide plate 30 is made of a transparent synthetic material such as polymethyl methacrylate, which is inexpensive, has good optical properties and can be easily processed. However, plate 30 may be made of glass.

The slot disk 29 was assumed to be fixed earlier.

The absolute value of the angular velocity of the object is measured. Under this annulus, it may be necessary to measure the relative angular velocity of this object relative to a reference value, for example the angular velocity of another object. Slot disk 29 may be arranged to rotate, driven by a second object to rotate at a constant reference speed.

In the arrangement according to the invention, the functions of the slotted discs 23, 29 can be exchanged, ie the disc 29 is driven by an object and the disc 23 rotates at a fixed or reference speed.

In order to detect the direction of rotation as well as the rotational speed of the object, measurements known in the art of optical displacement sensors can be used in the device according to the invention. To this end, in addition to the first ring with slit, a second ring with slit is provided on one of the disks, while the second detector only receives radiation from the second slotted ring, while the first detector It only receives radiation from the first slot ring. 4 shows a portion of a disc with two slotted rings 25, 25. These rings have the same tangent period (P). However, the slit 24 in the ring 25 is tangentially biased at least 1/4 P relative to the slit 24 'in the ring 25'. The other slot disk has one ring with a slit of sufficient length to cover the slits 24, 24 '. However, other slot disks may alternatively have two rings with slits in which the slits in the first ring are not biased relative to the slits in the second ring.

The output signals of two detectors (not shown), one receiving only radiation from the slit 24 and the other receiving only radiation from the slit 24 ', show a phase difference. By determining the leading signal among these signals, it is possible to establish the rotation direction of the disk 23, i.e., the object.

In order for the measured signal to be independent of the imperfections of the element or its components, for example, the intensity of the radiation source can be adjusted to a low frequency. This has the same effect as modulation at a constant frequency of angular velocity of the rotating disk. Therefore, a low frequency modulation component may be superimposed on the detection signal. This provides for example the elimination of the inaccuracy or imperfection effects of the control circuit 16.

Another possibility of obtaining a measurement signal independent of imperfection is the use of a second radiation beam or a reference beam from the same radiation source or a second radiation source, which follows the same path as the measurement radiation through the device but does not pass through the slotted ring. Received by a reference detector. By subtracting the signals of the measurement detector and the reference detector, a corrected measurement signal is obtained.

As mentioned above, detecting the rotational direction of one of the disks with a second rotating disk with stops, a second ring with stops, and obtaining a measurement signal independent of the imperfection of the system are all embodiments described below. Can be realized in the field.

5, 6a and 6b show structurally more detailed embodiments of a measuring device, for example targeting a friction roll driven by a tape and fully incorporated therein.

5 is a sectional view of an element of the measuring device, and FIGS. 6A and 6B are perspective views. The roll 35 is a hollow cylinder with a thick wall. On this roll, a radiation guide plate 40, which is usually made of PMMA, with a beveled edge 57, is fixed. Alternatively, the radiation guide plate may be integral with the roll, as shown in FIG. The plate 40 is fixed with a slotted first disk 23. The friction roll 35 has a double wall tube 42 moving together. The central opening 43 of the tube 42 receives the shaft 44.

When the roll is driven, the tube 42 and shaft 44 also rotate. The shaft with its pointed end is journal supported by a membrane 41 fitted into the central opening of the slotted disk 29 and a plate 45 in the lighting housing 46 forming part of the lighting system. The roll 35 is journal supported by a ball bearing as well as the pivot bearing shown in FIG. Smooth bearings should be used so that the tape can easily drive the roll 35. Other parts of the lighting system are the cavity and radiation guide plate 40 between the inner and outer walls of the tube 42.

The radiation housing includes, for example, a compartment 47 for a radiation source 48 such as a light emitting diode (LED) and a radiation guide 49 such as PMMA fixed to the compartment. Lenses 50 for concentrating radiation emitted by the source 48 may be arranged in the transition between the compartment 47 and the radiation guide 49. This lens is for example a collimator lens. Only two diameter peripheral portions 51, 52 of the measuring beam are shown in broken lines. The measuring beam radiation is reflected on the inclined end face 53 of the radiation guide either through total internal reflection or through a reflective coating on the end face. The radiation of the reflected measuring beam then passes through the space between the inner and outer walls of the tube 42 so that the beam of annular cross section is incident on the conical reflector 55. This reflector spreads the radiation in the horizontal plane to 360 ° and sends it to the radiation guide plate 40. The slanted edge 57 of this plate reflects radiation as a beam of annular cross section to the slotted disks 23, 29. The radiation passed by the slits of these disks is moved to the radiation guide plate 30 through the inclined edge 31 of this plate. The radiation is then reflected towards the opening 33 by the conical reflector 32 of the plate. In this opening position an additional radiation guide 60 is fixed to the plate 30, which guides the radiation through the reflector on the inclined side 61 to the detector 34 disposed in the detection housing 65. will be. A transition 66 between the housing and the radiation guide 60 may be provided with a lens 66 for concentrating radiation on the detector.

By using various radiation guides, the radiation path from the source 48 to the detector 34 is blocked from around it, so that radiation from the source does not get lost at all and no ambient radiation can be incident on the detector at all. Thus, a measurement signal is obtained which satisfies the signal-to-noise ratio and is not affected by the surroundings.

The detection system with the optical housing 46 with the plate 45 and the slotted disk 29 is fixed to the common support 70.

Since the shaft 44 of the friction roll 35 and the slotted disk 23 are fixed on the plate 45 and the slotted disk 29, the slotted disks are journaled stably with respect to each other, and thus A stable and reliable measuring device is obtained. The angular velocity measuring devices shown in FIGS. 5, 6a and 6b can be quite compact so that they can be easily assembled.

In an embodiment of the measuring device, the slotted disks have a diameter of 1 cm. The period of the slit structure is approximately 80 μm and the slits have a length of approximately 350 μm. The entire device has a volume of approximately 1 cm ³ . In the embodiment of Fig. 5, the radiation source and the detector are located at the same position in the horizontal direction.

Thus, these parts can be provided on a printed circuit board that can be fixed to the support 70, which is quite advantageous from a structural point of view.

Due to the large number of slits that can be provided on the disc, the resolution capability of the measuring device is approximately ten times more than known angular or tape tachometers. Because of the accuracy the device can exert and the uniformity of the measurement radiation, the accuracy at which the angular velocity is determined is almost ten times greater than that of known angular or tape speedometers.

7 shows a second embodiment of a tape speed measuring device. Parts similar to those in FIG. 5 bear the same reference numerals. The measuring device of FIG. 7 is distinguished from that of FIG. 5 in that there is no slotted separating disc and the radiation guide plates 40, 30 are provided with slit rings 25, 27. In addition, the radiation guide plate 40 is integral with the friction roll 35 'and the assembly is made of a transparent synthetic material such as PMMA. The roll 35 ', which does not have a separate rotating shaft in the case, is journal-supported by ball bearings 80 and 81 instead of pivot bearings. The roll 35 'has two hollow spaces 82, 83 and peripheral portions 85, 86 between the central portion 84 through which the measurement radiation passes. In the device of FIG. 7, the measurement radiation passes through the same path as the device of FIG. 5. Compared to the measuring device of FIG. 5, the measuring device of FIG. 7 has the advantage of being more integrated and easier to assemble.

The apparatus of FIG. 7 is particularly suitable for the use of other forms of stops, such as grooves, for example instead of slits. The radiation guide plate is the entire internal reflecting plate, ie the radiation bound to these plates remains captured on these plates by the total internal reflection on the smooth plate surface. The radiation may protrude from the plate only at locations where smoothness deviations occur, such as where the protrusions or grooves are provided on the plate surface. The radiation may enter a radiation guide plate, such as plate 30, through a protrusion or groove.

FIG. 8 shows a cross-sectional view of a part of the radiation guide disks 90, 91 provided with grooves 92, 93 and which can be used in the apparatus of FIG. 7. The measuring radiation may exit from the disk 90 via the groove 92, which may enter the disk 91 via the groove 93, enter through the groove 92 and couple into the disk 93. The portion of radiation that is made depends on the position of the groove 92 relative to the position of the groove 93.

Grooves can be created in the disc by scratching the surface of the disc with sharp strings or needles. A simple and inexpensive way to obtain a radiation guide disc with grooves or protrusions is to print this plate by duplicating, starting from a master plate with a surface profile that is a mirror image of the desired profile.

This disc is then molded simultaneously to provide a groove pattern. The replication process is particularly suitable for mass production for consumer use.

9 schematically shows an embodiment of the second class apparatus for measuring the angular velocity of the roll. This roll 100 is fixed to the first radiation guide disk 101 which moves together. It is an annular disk 102 which is fixed, for example in a fixed manner, on a support 103 provided with a second radiation guide disk detector 104 and a lens 109. The main difference between this embodiment and the previous embodiments is that the edge of the disc is provided with a pattern of breaks 105, 106 and the longitudinal direction of the break is parallel to the rotating shaft 107 of the roll 100. The stop may be a surface deformed portion, such as a groove, or a slit.

A radiation source 108 for moving its radiation into the disk, for example an LED, is disposed opposite the disk 102.

Because of the rotationally symmetrical shape of the disk, the radiation is uniform. The radiation exiting from the disk 102 via the pattern of the stop 106 enters the disk 101 via the pattern of the stop 105.

This radiation is disposed in the center of the disk 101 and directs the radiation through the surface 110 of the disk 101 at the radiation transmitting portions 111, 112 of the support 103 and the lens 109 and the detector behind it. To reflect.

During operation, the instantaneous dose of radiation passed by the patterns of the breaks 106 and 105 and the amount of radiation to the detector is determined by the tangential position of the break of the pattern 106 relative to the position of the break of the pattern 105. . Thus, the instantaneous frequency of the detector output signal is proportional to the instantaneous angular velocity of the roll 100 or the instantaneous linear velocity of the object driving the roll, for example a tape.

The rotational speed of the motor can be measured directly by the device of the present invention, which is very compact and can therefore be combined with the motor. 10A and 10B illustrate vertical and horizontal cross-sectional views of an embodiment of an assembly of a motor and a measuring device. The shaft 121 protruding from the motor 120 passes through the block 122 of the support 123.

This shaft is fixed in the first radiation guide disk 124, so that the disk moves with the motor shaft. The second radiation guide disk 125 is fixed to the block 123. Both disks have an annular stop pattern 126, 127, which may be a slit or a groove, for example. On the face of the stationary radiation guide disk 125, a radiation source 129 is arranged against which the radiation is coupled into the disk 125 via the radiation guide 130. After reflecting off the inclined sides 131, 132, 133 of the disk 125, radiation is incident on the pattern 127. The radiation passing through the pattern enters the rotating disk via the pattern 126 and moves therein towards the conical reflector 133. The reflected radiation exits from the disk 124 via the face 134 and reaches the detector 135.

The instantaneous frequency of the output signal of this detector is reached again. The instantaneous frequency of the output signal of this detector is again proportional to the instantaneous angular velocity of the motor 120 and the disk 124.

11a and 11b show a second embodiment of the device in vertical and horizontal cross sections, wherein the rotational speed of the motor can be measured directly. The shaft 121 protruding from the motor 120 is fixed to a holder 140 connected to the first radiation guide disk 141 moving together with the shaft 121. A second annular, radiation guide disk 142 is disposed around the first circular disk 141. Patterns of stops 144, 145, which may be slits or grooves, are disposed at the outer edge of disk 141 and the inner edge of disk 142, respectively. For example, a radiation source 147, such as an LED, is disposed within the support 143 and passes the radiation into the disk 142 via the radiation guide 148. The radiation path through this device is similar to that through the device of FIG. 9, where the elements 140, 150, 151 in FIG. 11A have the same function as the elements 55, 109, 104 in FIG. 9. Have

A reference beam may be used in addition to the measurement beam to further improve the accuracy of the device. The reference beam may be supplied by a separate radiation source but is usually from a source that supplies the measurement beam. The reference beam traverses parts such as the measuring beam, except for the pattern of the interruption, and is received by a separate detector separated from the measuring beam. Before the measuring radiation reaches the opposite side 57 of the disk 40, a portion of the measuring radiation is from the disk as a reference radiation in the device of FIG. 7 by a partially transparent reflector in the disk or via an annular groove in the disk. It is disengaged and received by a separate detector disposed within the disk 30. The measurement signal is the difference between the reference detector and the output signal of the measurement detector. This signal is no longer affected by the inaccuracy of components that may be in the radiation path.

12 shows a preferred embodiment of a device capable of measuring the rotational speed of the motor 120 or friction roll 100 and having a circular disk 160 and an annular disk 161. The disk 161 constitutes an annular protruding edge of the fixed radiation guide disk 162 having a U shape in cross section. When the circular disk is driven by the motor 120, the disk 162 is connected to the motor housing via the tubular connecting member 163. As shown in FIG. 12, the underside 164 of the disk 162 is provided with a radiation source 175 such as, for example, an LED whose radiation enters the disk 162 via a window. The radiation is incident on conical reflector 169 which radiates it over 360 ° in the horizontal plane. This radiation is radiated by the inclined surfaces 165, 166 of the disk 162 and then reaches the pattern 171 of the stop in the annular disk portion 161. Insert D of FIG. 12 shows a small portion of the pattern and inverse pattern 172 of the stop in driven disk 160. The pattern of the insert may again be a groove pattern or a slit pattern. Radiation through patterns 171 and 172 is incident on conical reflector 168 which reflects it and aggregates it into a circular beam. The beam is incident on a detector 170 disposed on the top surface of the disk 162 via a window in the disk 160.

It is also possible to change the position of the detector 170 and the radiation source 175. The radiation then crosses a path opposite to that shown in FIG.

According to the apparatus of FIG. 12, evenly patterned illuminations 171, 172 can be obtained compared to the apparatus of FIGS. 9, 11a and 11b, in which the radiation covers a long path through the radiation guide disc and the This is because it is reflected several times inside the disk.

As already mentioned, the disc 160 may be driven by a friction roll instead of a motor. The apparatus of FIG. 12 may then also be used, for example, to measure the linear velocity of the tape driving the friction roll.

FIG. 13 shows an embodiment of a tapescanning apparatus for playing an analog compact cassette, for example. In FIG. 13 only relevant parts of the tape scanning apparatus of FIG. 1 are shown. The motor 11 is for driving the winding reel 9 so that the magnetic tape 2 moves in the direction of the arrow along the regeneration head 1 and the friction roll 21. The output of the reproduction head 1 is connected to the input of the A / D converter 200 and the output of the converter is connected to the input of the buffer memory 202. The output of the buffer memory 202 is connected to the input of the D / A converter 204, and the output of the converter is connected to the output terminal 206. The analog audio signal read from the tape 2 can be used at the output terminal 206.

There is a first clock signal generator means in the form of a phase locked loop 208, which loops from the tacho pulse of the device 20 comprising the friction roll 21 to a first clock signal of frequency f1. Induce. This clock signal f1 is shown to the clock signal inputs 210 and 212 of the A / D converter 200 and the buffer memory 202. Since the frequency f1 of the taco pulse is derived from the device, the value of the frequency f1 can be changed by the frequency conversion of the taco pulse and by the conversion of the speed at which the tape 2 moves along the friction roll 21. will be.

The second clock signal generating means is in the form of a frequency oscillator adapted to generate a second clock frequency which is a fixed value. This clock frequency is applied to the clock signal inputs 216 and 218 of the buffer memory 202 and the D / A converter 204. The buffer memory 202 also has an output 220 for supplying a control signal indicating the charge level of the buffer memory 202. For this purpose the buffer memory 202 comprises detection means (not shown) for determining the charge level and thus inducing a control signal. The output unit 220 is connected to the input unit 224 of the motor control unit 222. The output of the device 20 may also be connected to the second input 226 of the control unit 222. According to a control signal applied to the input units 224 and 226, the motor control unit 222 supplies a motor control signal to the motor 11. The loop consisting of the feedback to the input 226 of the control unit 222 can then be regarded as a speed control loop, and the loop consisting of the feedback to the input 224 of the control unit 222 is regarded as a phase locked loop. Can be.

The tape scanning device operates as follows. The buffer memory 202 is for correcting the information signal read by the head 1 to the time base. This signal is surrounded by time error due to tape speed conversion. The recording clock frequency f1 is derived from the taco pulses of the device 20 and thus likewise subject to tape speed conversion. Therefore, the signal of the frequency f1 read by the reproduction head 1 is sampled to the A / D converter 200 and written to the buffer memory 202 at this frequency. As the tape moves faster, the frequency f1 increases inversely. When the sample is read at a fixed frequency f2, the signal at the output terminal 206 is free from the above-described conversion.

As the tape moves faster, more information signal samples will be stored in the buffer memory 202 at the same time interval. On average, if the write frequency f1 is higher than the read frequency f2, the buffer memory 202 will overflow at a given moment. To prevent this, a control loop is provided from the output 220 to the motor control unit 222. This control loop causes the charge level of the buffer memory 202 to halve on average. If the tape is moved at a speed such that f1 is larger than f2, the filling level 202 of the buffer memory 202 will be 1/2 or more. This control signal is applied to the motor control unit 222 where the speed is reduced.

If the feed rate is too low, it is obvious that the filling level is low. Thus the speed is increased by the control loop.

The combined time base correction and tape speed control described in connection with the thirteenth case is because the device 20 with the friction roll 21 is excellent in resolution, accurate and reliable. Moreover, the friction roll has the advantage that the speed control still works because in the trick mode in which the speed of the recording carrier is (multiple) faster than the normal playback speed, the friction roll keeps in contact with the magnetic tape 2.

Note that the write frequency f1 may also be given a fixed value. In this case the read frequency f2 must be derived from the taco pulse of the device.

Although the present invention has been described in connection with being used as a tape tachometer in a tape scanning device, it can also be used in other devices, for example plotters, in which the linear motion of a long object capable of driving a friction roll must be measured with high accuracy. As described above, the present invention may be used to directly measure the rotational speed of a motor, such as a reel drive motor, in a tape scanning apparatus.

The invention can also be used wherever an accurate and compact device is needed to measure the rotation of parts or objects. Examples include robots, tools, angle sensors, etc. in an anti-blocking brake system of a vehicle.

1 shows a part of a tape scanning apparatus in which the angular velocity measuring apparatus according to the present invention can be used.

2 shows the principle of the measuring device.

3 shows a slotted disk to be used in the apparatus.

4 shows a slotted disk which determines the direction of rotation of the object.

5 shows a first embodiment of the measuring device.

6a and 6b show in detail the structure of the measuring device for use in a tape scanning device.

7 shows another embodiment of the measuring device.

8 shows a portion of a radiation guide disc with a stop for use in the device.

9 shows an embodiment of a measuring device in which a stop pattern is provided at the disc edge.

10A and 10B show a device for measuring the rotational speed of a motor, similar to the seventh diagram.

11a and 11b show an apparatus for measuring the rotational speed of a motor, similar to the ninth diagram.

12 shows a preferred embodiment of a device for measuring the rotational speed of a motor.

13 shows an embodiment of a tape scanning apparatus according to the present invention.

※ Explanation of code for main part of drawing

1: scanning head 2: magnetic tape

3: cassette 4: electrical connection

5: electronic circuit section 6: amplifier and decoding circuit section

7: loudspeaker 8, 9: reel

10, 11: motor 13, 14: guide roll

16: motor control circuit 21: friction roll

23, 29: Disc 24: Slit

25 ring 26, 30: radiation guide plate

Claims (22)

A first rotating disk driven by a rotating object, a second disk, an illumination system for illuminating the entire pattern simultaneously, and a detection system, wherein the two disks are elongated in a periodic, rotationally symmetrical pattern on the disk surface. An apparatus for optically measuring the angular velocity of a rotating object having a stop, The illumination system includes a radiation source in the form of a diode and a radiation guide that aggregates the source radiation into a beam suitable for the cross section of the pattern, wherein the detection system receives radiation from the illumination system through the two patterns. And a radiation guide that aggregates the radiation into a beam of circular cross section, and a signal detector that converts the intensity change of the beam into an electrical signal. The method of claim 1, And the second disk is arranged to be stationary. The method of claim 1, And the second disk is driven at a constant angular velocity. The method of claim 1, One of the patterns is divided into stops of the first and second periodic and rotationally symmetric subpatterns having the same period, and the position of the stop of the second subpattern is relative to the position of the stop of the first sub-pattern. And a second detector for offsetting a distance corresponding to one quarter of the sub-pattern period, the radiation passing through the second sub-pattern and the pattern of the other disk. The method according to any one of claims 1 to 4, The first of the disks is a round radiation guide disk having a side and a stop pattern thereof is provided on the side, and the second disk is an annular radiation guide disk having an inner side facing the side of the first disk and A breakout pattern is provided on the inner side. The method of claim 5, The illumination system comprising an annular disk and a radiation source positioned opposite the outer portion of the disk, wherein the round disk has a conical reflector to form part of the radiation collection system. The method of claim 5, The annular disk comprises a protruding edge of a radiation guide disk having a U-shaped cross section and having a conical reflector therein, one disk surface supporting the radiation source and the other disk surface supporting the detector, The round disc has a reflector. The method according to any one of claims 1 to 4, Wherein the first and second disks each have a flat surface, and a stop pattern is disposed on these flat surfaces facing each other, and the stop pattern of each disk is an annular pattern. The method of claim 8, The two disks are radiation guiding disks, one of which forms part of the illumination system and the other of which forms part of the collection system, radiation is trapped in the disks due to total internal reflection, and radiation is the disk. And exit from the disk associated with the lighting system via a break pattern in the chamber, and enter a disk associated with the collection system via the break pattern in the disk. The method according to any one of claims 1 to 4, And the stop portion comprises a groove on a smooth disk surface. The method according to any one of claims 1 to 4, And the stop portion comprises transparent slits on the opaque disk surface. The method of claim 8, At least one of the disks is made of a transparent synthetic material. The method of claim 8, The disk is opaque and the stop is comprised of slits in the disk, and the illumination system has an annular cross-section beam having an inner diameter of less than or equal to the radius of the slit of the annular pattern of the first and second disks. Measuring apparatus characterized in that for supplying. The method of claim 13, The illumination system further comprising a radiation source, a first radiation guide, and a rotating radiation guide disk having an inclined reflective edge and disposed adjacent to and parallel to the rotating disk. The method of claim 13, The synthesis detection system includes a second radiation guide disc having an inclined reflective edge and disposed away from the slotted rotating disc of the slotted second disc, wherein a conical reflector is disposed in the center of the second guide disc. Characteristic measuring device. The method of claim 15, At least one of the two radiation guide disks is made of a transparent synthetic material. The method of claim 15, And a second radiation guide for guiding radiation from the conical reflector to the detector is disposed between the second radiation guide disk and the detector. The method of claim 17, The radiation source, the first radiation guide, the second radiation guide disk, the second radiation guide and the detector are arranged in a U-shape, a portion of the first radiation guide forming a central portion of the U-shape and receiving a rotating shaft. In order to have a hollow tube shape. The method according to any one of claims 1 to 4, And the rotating object is a friction roll driven by a moving elongated object to convert the device into a linear velocity measuring device. Two reels used as feed reels and winding reels, a scanning head disposed in a path covered by the tape between the two reels, a tape speed sensor, and a control circuit for controlling the speed of the winding reels A tape scanning apparatus having a tape speed control loop, The tape speed sensor is a tape scanning device, characterized in that the measuring device of claim 19. The method of claim 20, A reproduction head for reproducing the information signal recorded on the tape, a buffer memory whose input portion is coupled to an output portion of the reproduction head and whose output portion is coupled to an output terminal for supplying an information signal; First clock signal generation means for generating and supplying a first clock signal having a first clock frequency at an output portion coupled to a write clock signal input portion of the buffer memory; Second clock signal generation means for generating and supplying a second clock signal having a second clock frequency at an output coupled to a read clock signal input of the buffer memory; Detecting means for determining a filling level of the buffer memory and supplying a control signal at the output unit, the control signal being a measurement of the filling level of the buffer memory, The buffer memory stores an information signal in response to a first clock signal and supplies an information signal stored in the buffer memory in response to a second clock signal, wherein one of the first or second clock signal generating means Generates a clock signal having a fixed clock frequency, the output of the speed sensor being coupled to the other input of either the first or second clock signal generating means, the other clock signal generating means being clocked in accordance with the electrical signal of the apparatus And a clock signal having a frequency, wherein the output of the detecting means is coupled to an input of a control circuit for controlling the speed of the winding reel. The method of claim 21, The tape scanning device is of analog type for reproducing an analog information signal recorded on a tape, and the device includes an A / D converter arranged between an output of the reproduction head and an input of the buffer memory, A D / A converter arranged between an output part and said output terminal, said A / D converter having a clock signal input part coupled to an output part of said first clock signal generating means, said D / A converter being said And a clock signal input portion coupled to an output portion of the second clock signal generating means.