DE2040073A1 - Mechanical scanning arrangement - Google Patents

Description

_r . ,,., ...,. _r . , ... ,, _r) 204U073

'· ■■' ■■ PHB. 31991.

'■■. ■. '·! . ~ 'L ..' v - .. iLA; iii ^J £ tii'AtiRIEi \ fci ^'i l JW / RV

- ™ - ·· PHB- 31 991

- \ .-: i _:. «: J: .t.-j vc.-n: tO.AugUst 1970

"Mechanical scanning arrangement" ·

The invention relates to a mechanical scanning arrangement, in which a scanning means is provided to deflect a light or other radiation path in such a way that this one line and Brings about image scanning.

Previous embodiments of such mechanical scanning arrangements use a rotating scanning means such as a Nipkow disk or a multiple lens / mirror element. From the magazine "The Wireless World and Hadio Review ", Kovember 11, 1922, pp. 197-201 it is known a light path to perform an approximate line and image scan using a mechanical scanning device in which a mirror is swung around two orthogonal axes.

The present invention seeks to provide an improved mechanical Scanning arrangement, wherein a scanning means is moved about two transverse axes

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schvunfjen becomes one around a light or other radiation path To have line and image scanning carried out »

The present invention provides a mechanical scanning device having scanning means capable of oscillating about a first axis with the line frequency is provided, which is determined by a natural mechanical resonance produced by the combination of the above Sampling by means of and a clock generator provided with it for setting a required value of the mechanical resonance frequency of the oscillation for said sensing means is determined in relation to the mass of the latter * and is flagged to indicate the first axis attached to a body that is at a lower, frame rate around a second axis oscillates, which is transverse to said first axis, said frame rate being associated with and synchronized with the line rate.

In one embodiment of the invention is said Clock suitably a piece of spring wire which is aligned with said first axis and between the scanning means and a point is attached to said body on which said scanning means ι is rotatably arranged to oscillate about said first axis. As is described, the mechanical resonance frequency of the oscillation of said scanning means is a function of the rigidity of this piece of spring wire in connection with the mass of the scanning means mounted in journals.

In a preferred embodiment of a mechanical scanning device according to the invention, said scanning means is a The mirror and the device have special application in the field of medical infrared thermography for line and image scanning

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ORIGINAL INSPECTED

/> Ί 7 Q -3- PHB. 31991.

for an infrared detector consisting of a single cell · here the device for the infrared detector consisting of one cell can scan fast enough, among other things, to receive an output signal from the detector, that on a cathode ray tube with a long afterglow phosphor to generate a thermal image of the scanned image · The clock means of the device enables in a simple manner lower the line frequency and consequently the frame rate to one for a constant display of the image during the scan.

An embodiment of the invention is in the drawings and is described in the following »It shows ·

Fig. 1 is a side view, partly in section, of a mechanical scanning device according to the invention;

Fig. 2 is a front view, partly in section, of the device of Fig. 1;

Fig. 3 is a schematic representation of the device according to Fig. 1 together with a drive circuit for this device

1 and 2 show a mechanical scanning device to produce a line and image scan for one of only one Cell existing infrared detector, using a single flat circular mirror. The line and image scanning is done by synchronized oscillations of the mirror in two perpendicular to each other standing levels. The oscillation frequencies are 96 Hz in the line direction and 1 Hz in the picture direction, which is one out of 96 lines existing image results in a field of view of about 18 degrees χ 12 degrees covered. On the other hand, an image sample of 2 Hz can be obtained, as explained below.

The mirror 1 consists of a glass plate (old one diameter

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• ^ KB-mi ^ Jm ^ ym ORIGINAL INSPECTED

-4- PHB. 31991.

knife of for example 2 inches and a thickness of 0.040 inches) which is ground, polished and aluminized on one side and fixed in an aluminum frame 2 by means of an epoxy resin glue. The frame 2 will attached at two diametrically opposite points on the inner rings of two self-aligning ball bearings 3 and 4. The outer rings of the bearings and 4 are held in a surrounding aluminum cage 5. The trunnion shaft 6 through the center of the bearing 4 is pierced and made by soft solder connected to the spring steel wire 7, the upper end of the wire 7 is fastened in a clamp arranged on the projection 9 of the KSfige 5. "An aluminum tongue 10 (e.g. 0.048 inches thick χ 0.375 inches wide) is attached, for example, by means of a threaded nut to the pin shaft 12 of the bearing 3, this tongue 10 being provided within of the gap of a tongue-switched oscillator 13 eu, which oscillator is attached to KSfig 5. An electromagnet 14 is also attached to KBfig 5 in the level of an anchor 15t made of mild steel and attached to the mirror frame 2.

The mirror system, i.e. everything in camps 3 and 4 rotatably arranged hearty, will oscillate sinusoidally in case of disturbance and the natural frequency of its oscillation is a function of the mass of the

Mirror 1 and the frame 2 of the same etc. and the rigidity of the spring steel wire 7.

When the electromagnet 14 thereafter once per complete Cycle of this natural frequency of the oscillation is excited, for example by switching the oscillator 15 switched by a reed Use of a suitable amplifier and pulse shaper, such as the au As can be seen from Fig. 3, the mirror system will still vibrate old an amplitude determined by the excitation voltage for the electromagnet

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1.4. 'Is-determined

For a line scan frequency of $ 6 Hz and an angular movement of 9.5 degrees for a mirror with a diameter of 2.0 inches, *

The effective mass of the mirror system »for the glass mirror (2 inch diameter χ 0.040 inch thickness χ

0.095 engl. Pounds / inch ³ ) - 0.0119 engl, pounds - W ₁

for frame 2 (0.18 ″ wide 0.024 inch thick

χ 0.097 engl. Pounds / inch ³ ) 0.0028 engl. Pound - w _? for anchor 15 (0.18 "wide by 0.032" thick

x 1.375 Inoh long χ 0.283 English pounds / inch ⁵ ) «0.0025 English Pound - w. For a simple harmonic movement, "

Time for a complete cycle - T - ΊΤΤψξ 0)

w 2 where I »is the moment of inertia of the vibration system ■ TT ^k where C · rigidity of the spring steel wire 7 in pounds / torsion adi an t, where K is the turning radius of the mirror system *

k for the glass mirror 1 ^m \ ^m 0.5 inch - k.

k for frame 2 - V 2 * ° ' ⁷ ° ^{7 Inoh}

1 _v / Sin 4 (
² V 8OX

k for the anchor 15 - r? \ /. 0.924 - kj

wk ² wk ²

Total I ■ ——— + ——

(0.0119 X .5 *) + (0.0028 χ .707 ² ) 1

12 χ 32.2] (0.0023 x.

- 0.00258 (0.00298 + 0.0014 + 0.00196)

- 0.00258 χ 0.00634

1 09809/1 SOS

OfifQINAL

O '■ - Ί Ί

-6- PHB. 31 ^ 91.

- 16.4 χ 10 ~ ⁶ (English pound / inch units) For a sampling frequency of 96 Hzt T - 0.0104 sec. and from

_2

^£ 10

- 2.44

. '. C = 2.44 ²

■ 5 »95 in engl. Pounds of torque / torsional radiant,

"And -" -s "· = - A Morley number of materials r J Jj

ART 108

where fs = maximum torsional stress in the spring wire r - radius of the wire T * 5.95 in engl. Pounds / radians

G. 12 χ 10 ⁶ engl pounds / inch ² (for spring steel)

Q ' 1 radian

L - wire length L - JG £

ml _Y 12 χ 10 ⁶ _T , ■ 32 5.95

- d ⁴ χ 19.8 χ 10 ⁴

and for a wire diameter of, 04Θ (1Θ SWG) ι L - 0.0484 19.8 χ

“1.05 inches
and for a scan of 9i5 degrees of torsion angle - 4 »75

^{x 7} ^ ^Radians

*. Maximum torsion stress in wire fs · —r—

Xj

109809 / 150S Orig.nal inspected

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0.024 χ 12 χ 10. ⁶ χ 4.75 χ7ΐ
1.05 180

- 22,800 engl. Pound / inch ²

The above number is used for a carbon spring steel wire (for example Steel wire) where peak torsional stresses of up to 50,000 or.gl, pound / inch 'are acceptable in most cases.

An image scan is obtained in that the aluminum cage 5 around shafts 16 and 17 »which are in bearings 18 and I9, those on the E'.iaaerer. Eefeetigungsbügel 20 are arranged, is tilted, Dieter BefesticungebUgel 20 also carries a drive motor 21 for the image scanning, which motor can suitably be a Philipe stage motor type AU5O55 / 8O. The motor 21 drives a 2 / i reduction box 22, on its external shaft 23 an exient 24 by means of a ball and rod connection 25 "nit ier shaft 17 is connected,

The step motor 21 is, for example, from the tongue-switched oscillator 1? fed via a suitable switching and pulse shaping circuit, as described with reference to FIG. 3. For each Sewegur.eezyklue of the mirror system the step motor 21 will turn one pole and for a line scanning frequency of 96 Ez when using a motor with 46 foIeπ the motor shaft speed will be 46 steps / s or, ■ * ~ «= 2 Hz. With the 2 / I reduction box 22 on the motor shaft 4 "

the frame rate will be 1 Hz. Without the gear box it will the image scanning frequency 2 Hz, so that the 96 lines of the line scan are scanned as two fields.

Fig. 3 shows a schematic representation of the mechanics Scanning device, the mirror is indicated by Mi, which is around a vertical axis (as can be seen in the drawing) is rotatable and the KSfig with Ca, which can be rotated around a horizontal axis (as in the drawing

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visible). The electromagnet is indicated by EH, the tongue-locked oscillator by VSO, the stepped motor by MO and the gear box by Ge. The drive circuit for the mechanical The scanning device contains an electronic switch ES for feeding the step motor NO, which switch generates an output signal for the step motor for responding to an output pulse of the reed-switched oscillator VSO, the electronic switch ES, which performs switching and pulse-shaping functions as a function of this output pulse, is suitably parts I and III of the electronic switch from Philips 2,727,6. The drive circuit contains a power amplifier PA, an inversion amplifier 1A and a pulse shaper PS to excite the electromagnet EN in order to maintain the oscillation of the mirror system at its mechanical vibration frequency. The output pulse of the reed-switched oscillator VSO is amplified, inverted and shaped and through these three elements PA, IA and PS to generate an excitation pulse for the electromagnet EK, once per cycle of the mechanical resonance frequency of the mirror eystea

109809/1 SOS

Claims (1)

2 O 4 υ ü 7 3 -9- PHB. 31991. PATENT CLAIM Et , 1.J Mechanical scanning device with a scanning means that to vibrate about a first axis at a line frequency determined by a natural mechanical resonance is determined by the combination of said sampling means and a clock means is given that with it is provided by a required value of the mechanical resonance frequency of the vibration for said scanning means as a function of of the mass of the latter, the first axis being arranged on a body intended to oscillate at a lower frame rate around a second axis that is perpendicular to the first Axis, said frame rate being related and synchronized with the line rate, characterized in that the synchronization is obtained by means of a tongue-held oscillator, the is controlled by a tongue which is arranged on said scanning means to generate its output signal once per cycle of the Vibration of the detergent in response to the displacement of the tongue when the scanning means vibrates, and the vibration of said Scanning means about said first axis by an electromagnet which works together with a magnetic link on the said scanning means is arranged or forms part of the same and which can be excited once per cycle of the oscillation of said scanning means in order to generate a magnetic field sum attracting said magnetic member around said scanning means at a line frequency deflect, this excitation of the electromagnet once per cycle the oscillation of the scanning means In response to the το »named Zungenge schal te oscillator generated output signal takes place and where the Vibration of the named body around the named second eighth through inner 109809/1 SOS Grandma ,, * «. -10- PHB. 51991. Step aoxor is made to turn in discrete steps in response to the successive output signals of the said tongue-switched Oscillators can be excited. 2 · Mechanical scanning device according to claim 1, characterized in that a drive between the said body and the motor shaft of the stepped motor has an eccentric arranged on the output shaft Contains a ball and rod connection with the aforementioned Body is connected 3. Meohanisohe scanning device according to claim 2, characterized in "indicates that between the · body and the motor shaft · of the stepped motor a drive is present which contains a Nookeη attached to the output shaft and a rotatable cam follower, the old one Body is coupled » 4 · Meohanic scanning device according to claim 2 or J »thereby characterized in that a reduction box is fitted into the drive between the stepped motor and the said body, 5. Mechanical scanning device according to claim 1, characterized in that said tact old valley is in 9t (Ick is spring wire, the old aligned with the first axis mentioned and between d ·· sample ·! ttal and a Stella on the named body where daa named scanning means to » Swinging does dia called · first · Aohse is rotatably arranged, attached iet. 109809 / I SOS ORIGINAL INSPECTED