CA1147383A - Automatic stripe width reader - Google Patents
Automatic stripe width readerInfo
- Publication number
- CA1147383A CA1147383A CA000342372A CA342372A CA1147383A CA 1147383 A CA1147383 A CA 1147383A CA 000342372 A CA000342372 A CA 000342372A CA 342372 A CA342372 A CA 342372A CA 1147383 A CA1147383 A CA 1147383A
- Authority
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- Canada
- Prior art keywords
- stripes
- photodetecting
- signals
- stripe
- width
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Length Measuring Devices By Optical Means (AREA)
Abstract
RCA 73,558 Abstract Apparatus is provided for determining the widths and spacings of substantially parallel opaque stripes on a substrate, wherein the stripes are separated by openings.
The apparatus comprises a light source for illuminating the substrate and photodetecting means positioned to receive light from the illuminated substrate. Means are included for scanning the photodetecting means transverse to the stripes and for sweeping the photodetecting means in a direction substantially parallel to the stripes. The apparatus further includes means for converting the output of the photodetecting means into a quantized signal, means for dividing the quantized signal into separate signals representing stripe widths and opening widths between stripes, and means for converting the stripe width and opening width signals into a signal representing center-to-center spacing between openings.
The apparatus comprises a light source for illuminating the substrate and photodetecting means positioned to receive light from the illuminated substrate. Means are included for scanning the photodetecting means transverse to the stripes and for sweeping the photodetecting means in a direction substantially parallel to the stripes. The apparatus further includes means for converting the output of the photodetecting means into a quantized signal, means for dividing the quantized signal into separate signals representing stripe widths and opening widths between stripes, and means for converting the stripe width and opening width signals into a signal representing center-to-center spacing between openings.
Description
-1- RCA 73, 558 AUTOMATIC STRIPE WIDTH READER
Back~round of the Invention This invention relates to measurement of the S widt~ of stripes and spacin~ between stripes in a regular periodic pattern, and particularly ~o a reader for performing such measurements.
Although the present invention may be used to read the widths of many different types of regular periodic patterns, it hereinafter will be described with respect to reading the widthsof opaque, light absorbing lines on a color picture tube faceplate panel of the matrix type before application of phosphor elements of a viewing screen.
-Color picture tubes of the line screen matrix type have been commercially available for several years.
The screens of such tubes comprise alternating lines of red, green and blue light-emitting phosphors, each separated from the other by light absorbing stripes called the matrix. In forming the tube screen, the matrix is applied first to the inner surface of a tube faceplate panel and then the phosphor lines are applied. The matrix and the phosphor lines are formed in a photographic process which uses the shadow mask of the tube as a photomaster. Each color-emitting set - of phosphor eIements requires a different light source .~ .
- ~ location to ensure placement of the elements at locations that will be struck by electrons from an associated electron gun. Since the matrix is applied before the phosphor elements are applied, formatLon of the matrix requires~three separate exposures to ~;~ ensure that the holes in the matrix for the phosphors are in the proper locations O Because of this multiexposure method, the width of the matrix stripes and the spacing between stripes may vary from the ideal width and spacing desired. Since light output and color purity are at least partially dependent on the matrix stripe i width and spacing, it is advantageous to determine this stripe width and spacing prior to completion of a screen.
,. .
; ', -~73~3 1 -2- RCA 73,558 Summary of the Invention Apparatus is provided for determining the widthsand spacings of substan~ially parallel opaque stripes on a substrate, wherein the stripes are separated by openings. The apparatus comprises a light source for illuminating the substrate and photodetecting means positioned to receive light from the i huminated substrate. Means are included for scanning the photodetecting means transverse to the stripes and for sweeping the photodetecting means in a direction substantially parallel to the stripes.
~he system further includes means ~or converting the outpu~ of the photodetecting means into a quantized signal, means for dividing the quantized signal into separate signals representing stripe widths and opening widths between stripes, and means for converting the stripe width and opening width signals into a signal representing center-to-center spacing between openings~
.~ .
Brief Description of the Drawings FIGURE 1 (Sheet 1) is a side view of the aeneral physical structure of a stripe width reader.
FIGURE 2 (Sheet 1) is a Partial ~lan view ~f a t~e faceplate having an ideal matrix pattern thereon.
.
~ 30 ~ - ' . ~ ., .
:
~7383 -1 -3- RCA 73,558 FIGURE 3 (Sheet 1) is a partial plan view of a tube faceplate having an actual matri~ pattern thereon.
FIGURE 4 (Sheet 2) is a circuit diagram for calcu-5 lating spacing distances Sn from inputs related to stripewidth An and the spacings bet~een stripes Bn.
FIGURE 5 (Sheet 2) is a small portion of a tube ~aceplate panel having a stripe pattern thereon with an over-lay showing the area of the panel to be measured.
FIGURES 6 and 7 (Sheet 3) are a front view and a cutaway side view, respectively, of a camera unit.
FIGURE 8 (Sheet 4) is a circuit diagram showing the interconnection of circuits in the present stripe width reader.
FIGURE 9 ~Sheet 2) shows waveforms of quantized signals relat~d to stripe widths and stripe spacings.
FIGURE 10 (Sheet 5) is a diagram of a data process-ing circuit.
Detailed Description FIGURE 1 illustrates the general physical arrange-ment of a stripe width reader 10. Various reader components located on a chair-llke stand 12 having a table section 14 and a vertical extension 16. A faceplate panel 18 is shown posi-tioned on the table section 14 on a sliding tray 20. The 25 panel 18 is held on the tray 20 by movable jaws, not shown.
The tray 20 may be clamped in positions which determine the area of the panel I8 to be measured. A camera unit 22 is suspended directly abo~e the panel 18 by a cable 24 which passes through pulleys on an arm 26 which is attached to the 30 vertical extension 16. Vertical position of the camera unit 22 is controlled by a hydraulic mechanism 28 acting on the cable 24. For a stripe width reading, the hydraulic mechan-ism 28 lowers the camera unit 22 until it touches the sur~ace of the panel 18. Camera control electronics 30 are located at 35 the top of the vertical extension 16 and are connected to the camera unit 22 by electrical leads 32.
The panel 18 is illuminat-ed from below by an incandescent light source 34. Light from the source 34 passes through a Fresnel lens 36 which acts as a condenser. This 40 lens 36 is large enough to accommodabe the camera field of -view taking into account the variable angle at which the camera - may rest on the panel. A filter 38 also is included on the ~73~3 1 -4- RCA 73,558 lens 36 to cut out any infrared component which would cause a deterioration of image resolution.
The sensitive element in the camera unit 22 is a 172 5element line-scan photodiode array with elements spaced 15~m a-part.The matrix image is magnified about 7 times so the array scans a line about 3.556 mm long. The image is deflected across the array, in a direction perpendicular to the array direction, by a rotatable mirror. The effective distance ept on the matrix during measurement is about 2.54 mm . Width measurements made on the video signal during the sweep time are agyregated to form an average width value as described below.
FI~URE 2 shows a portion of a faceplate panel 40 15having ideally spaced and shaped matrix stripes 42 thereon.
Matrix stripe width is designated Ao~ the spacing between stripes 42 is designated Bo and the repeat distance, which is the same as Ao plus Bo~ is designated SO. Unfortunately, the ideal is never achieved; rather,the matrix stripe pattern 20varies both in spacing and in stripe width as shown in the actual embodiment of FIGURE 3. In this embodiment, the average widths of the matrix stripes 44 on the faceplate panel 46 are designated Al, A2 and A3, the average spacings between stripes are designated Bl, B2 and B3 and the average matrix spacings
Back~round of the Invention This invention relates to measurement of the S widt~ of stripes and spacin~ between stripes in a regular periodic pattern, and particularly ~o a reader for performing such measurements.
Although the present invention may be used to read the widths of many different types of regular periodic patterns, it hereinafter will be described with respect to reading the widthsof opaque, light absorbing lines on a color picture tube faceplate panel of the matrix type before application of phosphor elements of a viewing screen.
-Color picture tubes of the line screen matrix type have been commercially available for several years.
The screens of such tubes comprise alternating lines of red, green and blue light-emitting phosphors, each separated from the other by light absorbing stripes called the matrix. In forming the tube screen, the matrix is applied first to the inner surface of a tube faceplate panel and then the phosphor lines are applied. The matrix and the phosphor lines are formed in a photographic process which uses the shadow mask of the tube as a photomaster. Each color-emitting set - of phosphor eIements requires a different light source .~ .
- ~ location to ensure placement of the elements at locations that will be struck by electrons from an associated electron gun. Since the matrix is applied before the phosphor elements are applied, formatLon of the matrix requires~three separate exposures to ~;~ ensure that the holes in the matrix for the phosphors are in the proper locations O Because of this multiexposure method, the width of the matrix stripes and the spacing between stripes may vary from the ideal width and spacing desired. Since light output and color purity are at least partially dependent on the matrix stripe i width and spacing, it is advantageous to determine this stripe width and spacing prior to completion of a screen.
,. .
; ', -~73~3 1 -2- RCA 73,558 Summary of the Invention Apparatus is provided for determining the widthsand spacings of substan~ially parallel opaque stripes on a substrate, wherein the stripes are separated by openings. The apparatus comprises a light source for illuminating the substrate and photodetecting means positioned to receive light from the i huminated substrate. Means are included for scanning the photodetecting means transverse to the stripes and for sweeping the photodetecting means in a direction substantially parallel to the stripes.
~he system further includes means ~or converting the outpu~ of the photodetecting means into a quantized signal, means for dividing the quantized signal into separate signals representing stripe widths and opening widths between stripes, and means for converting the stripe width and opening width signals into a signal representing center-to-center spacing between openings~
.~ .
Brief Description of the Drawings FIGURE 1 (Sheet 1) is a side view of the aeneral physical structure of a stripe width reader.
FIGURE 2 (Sheet 1) is a Partial ~lan view ~f a t~e faceplate having an ideal matrix pattern thereon.
.
~ 30 ~ - ' . ~ ., .
:
~7383 -1 -3- RCA 73,558 FIGURE 3 (Sheet 1) is a partial plan view of a tube faceplate having an actual matri~ pattern thereon.
FIGURE 4 (Sheet 2) is a circuit diagram for calcu-5 lating spacing distances Sn from inputs related to stripewidth An and the spacings bet~een stripes Bn.
FIGURE 5 (Sheet 2) is a small portion of a tube ~aceplate panel having a stripe pattern thereon with an over-lay showing the area of the panel to be measured.
FIGURES 6 and 7 (Sheet 3) are a front view and a cutaway side view, respectively, of a camera unit.
FIGURE 8 (Sheet 4) is a circuit diagram showing the interconnection of circuits in the present stripe width reader.
FIGURE 9 ~Sheet 2) shows waveforms of quantized signals relat~d to stripe widths and stripe spacings.
FIGURE 10 (Sheet 5) is a diagram of a data process-ing circuit.
Detailed Description FIGURE 1 illustrates the general physical arrange-ment of a stripe width reader 10. Various reader components located on a chair-llke stand 12 having a table section 14 and a vertical extension 16. A faceplate panel 18 is shown posi-tioned on the table section 14 on a sliding tray 20. The 25 panel 18 is held on the tray 20 by movable jaws, not shown.
The tray 20 may be clamped in positions which determine the area of the panel I8 to be measured. A camera unit 22 is suspended directly abo~e the panel 18 by a cable 24 which passes through pulleys on an arm 26 which is attached to the 30 vertical extension 16. Vertical position of the camera unit 22 is controlled by a hydraulic mechanism 28 acting on the cable 24. For a stripe width reading, the hydraulic mechan-ism 28 lowers the camera unit 22 until it touches the sur~ace of the panel 18. Camera control electronics 30 are located at 35 the top of the vertical extension 16 and are connected to the camera unit 22 by electrical leads 32.
The panel 18 is illuminat-ed from below by an incandescent light source 34. Light from the source 34 passes through a Fresnel lens 36 which acts as a condenser. This 40 lens 36 is large enough to accommodabe the camera field of -view taking into account the variable angle at which the camera - may rest on the panel. A filter 38 also is included on the ~73~3 1 -4- RCA 73,558 lens 36 to cut out any infrared component which would cause a deterioration of image resolution.
The sensitive element in the camera unit 22 is a 172 5element line-scan photodiode array with elements spaced 15~m a-part.The matrix image is magnified about 7 times so the array scans a line about 3.556 mm long. The image is deflected across the array, in a direction perpendicular to the array direction, by a rotatable mirror. The effective distance ept on the matrix during measurement is about 2.54 mm . Width measurements made on the video signal during the sweep time are agyregated to form an average width value as described below.
FI~URE 2 shows a portion of a faceplate panel 40 15having ideally spaced and shaped matrix stripes 42 thereon.
Matrix stripe width is designated Ao~ the spacing between stripes 42 is designated Bo and the repeat distance, which is the same as Ao plus Bo~ is designated SO. Unfortunately, the ideal is never achieved; rather,the matrix stripe pattern 20varies both in spacing and in stripe width as shown in the actual embodiment of FIGURE 3. In this embodiment, the average widths of the matrix stripes 44 on the faceplate panel 46 are designated Al, A2 and A3, the average spacings between stripes are designated Bl, B2 and B3 and the average matrix spacings
2~easured from the center of one open space to the next are designated Sl, S2 and S3.
A major source of these stripe width and stripe spacing variations is error in the setting or exposure of the three separate light-houses which are used to form each of the
A major source of these stripe width and stripe spacing variations is error in the setting or exposure of the three separate light-houses which are used to form each of the
3~hree aperture fields in the matrix of stripes. Details of a method of making a cathode-ray tube screen having a matrix background of light-absorbing areas may be found in U.S. Patent 3,558,310 issued to E. E. Mayaud on January 26, 1971. Since the variations in each set of stripes formed with the same 3~ighthouse are similar (each lighthouse forming every third stripe), it is useful to group together measurements of the widths of openings in a given field even though these measure-ments are taken on different stripes. The method, therefore, is to aggregate aIl measurements o~ Al, all of Bl, etc., taken
4~uring the camera sweep. This aggregate is then scaled to give :,~
~72~83 1 -5- RCA 73,558 a read-out in volts corresponding to the average width, e.g., in mm.
The parameter of display chosen is not the average
~72~83 1 -5- RCA 73,558 a read-out in volts corresponding to the average width, e.g., in mm.
The parameter of display chosen is not the average
5 matrix stripe spacing B but the avexage repeat distance S, which can be more directly interpreted in terms of lighthouse maladjustment. Derivation of S values from A and B is accomplished by the circuit shown in FIGURE 4, wherein inputs A2, Bl and B2 are used to obtain output S2. In addition, the 10 width integrators are initialized at the (negative) desired or target value, so that the final values obtained represent deviations from the target values. Target values are appro-priately preset into the circuitry.
FIGYRE 5 shows a small portion 50 of a tube face-' 15 plate panel having a light absorbing matrix stripe pattern 52,but no phosphor line,s, thereon. The smaller shaded area 54 represents the area to be measured by the stripe width reader.
; In the figure, the scan direction of the photodiode array is left to right and the sweep direction of the camera is from 20 top to bottom. Each scan begins with a pause before informa-tion is gathered. Following the pause, information is not used until the leading edge 56 of the second stripe within the measured area i5 reached. Information to be processed is obtained during the scan over the next six stripes, and the en-5 able cycle ends at the leading edge 58 of the seventh stripe.
FIGURES 6 and 7 show the details of the camera unit .
22. Three seating pads 60 extend from a base 62 of the unit22 to contact the surface of a aceplate. Principal elements of the unit include a lens 64 for focusing the light from the 30 light source 34 and a focus motor 66 for moving the lens 64 -to its focused location. Light passing through the lens 64 is reflected by two mirrors 68 and 70 onto a detector array - 74. The first of the two mirrors 68 is attached to a sweep mirror drive 76 which rotates the mirror 68 thereby moving 35 the line viewed by the scanning array in the sweep direction shown in FIGU~E 5.
The electrical connections between the various components of the novel stripe width reader are shown in FIGURE 8. The camera unit 22 is controlled by the camera 40 control circuit B2. The first function of this circuit 82 is to focus the lens 64 after the camera unit 22 has been placed -1 -6- RCA 73,55~
on a faceplate panel. The focus motor 66 is provided with two speeds. One is a fast focus speed which continues until the lens 64 is nearly in focus. The other is a slower speed used 5 to bring the lens into final focus. To perform this focusing, a video processing circuit 84 generates a signal from the detector array 74 output which is proportionaltothe sharpness of the video signal. This signal then is fed to the camera control circuit 82.
Once the camera unit 22 is focused,thedetectorarray 74 scans the faceplate panel and the output is senttoa data processing circuit 86 via the video processing circuit 84.
During these scans, a mirror deflection power supply 88 feeds a constantly increasing current to the sweep mirror drive 76 lS causing the mirror 68 to rotate continuously so that each scan is slightly displaced from the previous one.This procedure continues until information is obtained from the entire measured area 54 previously sho~n in FIGURE 5.
The data processing circuit 86 provides six outputs 20 sequenced in pairs,Snand Bn,to two meters 90 and 92. The meters 90 and 92 contain analog-~o-digital converters, the outputs from which are fed to a printer 94. Two digits and a sign for each output give sufficiently accurate indication of the deviation from the desired or target values of S and B. A
25 third meter 96 indicates target values of Bo amd S~. Printer operation i5 sequenced by a printer control circuit 98.
The primary function of the video processing circuit 84 is to take the charge pulses from the detector array 74 and convert them into a quantized signal. The top waveform 100 of 30 FIGURE 9 shows this quantized signal.The next functicnperformed by the video processing circuit8~istDgate the combinedwaveform toobtainquantizedsignals ~or the various stripes,Al,A2and A3 and openings Bl,B2 and B3,as shown by the six lower waveforms of FIGURE 9. These individual waveforms are used as inputs to 35 the data processing circuit 86 shown in detail in FIGURE 10.
The data processing circuit 86 of FIGURE 10 comprises four basic parts: a switch section, an integrator section, a reference section, and a spacing calculation section. The - switch section includes an AND gate 102, a counter 104 and a 40 NOR gate 106 which provide one of the inputs to each of six ~ 173~3 1 -7- RCA 73,558 AND gates 108, 110, 112, 114, 116 and 118. The other inputs to these six AND gates are the stripe width waveforms Al, A2 and A3 and the opening wavefo~ms Bl, B2 and B3 from the video 5 processing circuit 84. Individual pulse trains of each waveform next are summed in the integrator section comprising six inte~rators 120, 122, 124, 126, 128 and 130 including their associated capacitors and resistors. The aiming voltage of the integrators is arranged so that a pulse length 10 corresponding to a specific stripe width (e.g., 0.25mm) gives a specific change on the integrator te.g., 1 volt).
Individual variations in the capacitors are compensated by trimming resistors. Outputs from the integrators 120, 122 and 124 are averages ~1~ A2 and A3 of the stripe width values, 15 and outputsfrom the integrators 126, 128 and 130 are averages Bl, B2 and B3 of the opening widths. Alternatively, as shown, the outputs may be preset to the desired values of stripe width Ao and opening width Bo. Thus, after summing, the outputs of the integrators will be the deviations of the 20 measured average values from the deslred or target values, which is a more convenient form of output. The target values ~re supplied by the reference section comprising the t~;o ampli~
fiers 132 and 134. Finally, the values of A - Ao and B - Bo are combined in the spacing calculation section comprising 25 the three networks 136, 138 and 140, essentially as previously described with respèct to FIGURE 4, to give S - SO values on the outputs from the networks. The outputs ~rom the three networks 136, 138 and 140 are thereafter sequentially ap~lied to the meter 90.
4~
FIGYRE 5 shows a small portion 50 of a tube face-' 15 plate panel having a light absorbing matrix stripe pattern 52,but no phosphor line,s, thereon. The smaller shaded area 54 represents the area to be measured by the stripe width reader.
; In the figure, the scan direction of the photodiode array is left to right and the sweep direction of the camera is from 20 top to bottom. Each scan begins with a pause before informa-tion is gathered. Following the pause, information is not used until the leading edge 56 of the second stripe within the measured area i5 reached. Information to be processed is obtained during the scan over the next six stripes, and the en-5 able cycle ends at the leading edge 58 of the seventh stripe.
FIGURES 6 and 7 show the details of the camera unit .
22. Three seating pads 60 extend from a base 62 of the unit22 to contact the surface of a aceplate. Principal elements of the unit include a lens 64 for focusing the light from the 30 light source 34 and a focus motor 66 for moving the lens 64 -to its focused location. Light passing through the lens 64 is reflected by two mirrors 68 and 70 onto a detector array - 74. The first of the two mirrors 68 is attached to a sweep mirror drive 76 which rotates the mirror 68 thereby moving 35 the line viewed by the scanning array in the sweep direction shown in FIGU~E 5.
The electrical connections between the various components of the novel stripe width reader are shown in FIGURE 8. The camera unit 22 is controlled by the camera 40 control circuit B2. The first function of this circuit 82 is to focus the lens 64 after the camera unit 22 has been placed -1 -6- RCA 73,55~
on a faceplate panel. The focus motor 66 is provided with two speeds. One is a fast focus speed which continues until the lens 64 is nearly in focus. The other is a slower speed used 5 to bring the lens into final focus. To perform this focusing, a video processing circuit 84 generates a signal from the detector array 74 output which is proportionaltothe sharpness of the video signal. This signal then is fed to the camera control circuit 82.
Once the camera unit 22 is focused,thedetectorarray 74 scans the faceplate panel and the output is senttoa data processing circuit 86 via the video processing circuit 84.
During these scans, a mirror deflection power supply 88 feeds a constantly increasing current to the sweep mirror drive 76 lS causing the mirror 68 to rotate continuously so that each scan is slightly displaced from the previous one.This procedure continues until information is obtained from the entire measured area 54 previously sho~n in FIGURE 5.
The data processing circuit 86 provides six outputs 20 sequenced in pairs,Snand Bn,to two meters 90 and 92. The meters 90 and 92 contain analog-~o-digital converters, the outputs from which are fed to a printer 94. Two digits and a sign for each output give sufficiently accurate indication of the deviation from the desired or target values of S and B. A
25 third meter 96 indicates target values of Bo amd S~. Printer operation i5 sequenced by a printer control circuit 98.
The primary function of the video processing circuit 84 is to take the charge pulses from the detector array 74 and convert them into a quantized signal. The top waveform 100 of 30 FIGURE 9 shows this quantized signal.The next functicnperformed by the video processing circuit8~istDgate the combinedwaveform toobtainquantizedsignals ~or the various stripes,Al,A2and A3 and openings Bl,B2 and B3,as shown by the six lower waveforms of FIGURE 9. These individual waveforms are used as inputs to 35 the data processing circuit 86 shown in detail in FIGURE 10.
The data processing circuit 86 of FIGURE 10 comprises four basic parts: a switch section, an integrator section, a reference section, and a spacing calculation section. The - switch section includes an AND gate 102, a counter 104 and a 40 NOR gate 106 which provide one of the inputs to each of six ~ 173~3 1 -7- RCA 73,558 AND gates 108, 110, 112, 114, 116 and 118. The other inputs to these six AND gates are the stripe width waveforms Al, A2 and A3 and the opening wavefo~ms Bl, B2 and B3 from the video 5 processing circuit 84. Individual pulse trains of each waveform next are summed in the integrator section comprising six inte~rators 120, 122, 124, 126, 128 and 130 including their associated capacitors and resistors. The aiming voltage of the integrators is arranged so that a pulse length 10 corresponding to a specific stripe width (e.g., 0.25mm) gives a specific change on the integrator te.g., 1 volt).
Individual variations in the capacitors are compensated by trimming resistors. Outputs from the integrators 120, 122 and 124 are averages ~1~ A2 and A3 of the stripe width values, 15 and outputsfrom the integrators 126, 128 and 130 are averages Bl, B2 and B3 of the opening widths. Alternatively, as shown, the outputs may be preset to the desired values of stripe width Ao and opening width Bo. Thus, after summing, the outputs of the integrators will be the deviations of the 20 measured average values from the deslred or target values, which is a more convenient form of output. The target values ~re supplied by the reference section comprising the t~;o ampli~
fiers 132 and 134. Finally, the values of A - Ao and B - Bo are combined in the spacing calculation section comprising 25 the three networks 136, 138 and 140, essentially as previously described with respèct to FIGURE 4, to give S - SO values on the outputs from the networks. The outputs ~rom the three networks 136, 138 and 140 are thereafter sequentially ap~lied to the meter 90.
4~
Claims (8)
1. Apparatus for determining the spacings between opaque stripes forming a light absorbing matrix on a color picture tube faceplate, the matrix having been formed by photoexposing the areas between the stripes in three separate exposures, said apparatus comprising: means for illuminating said faceplate, photodetecting means positioned to receive light from said means for illuminating, means for scanning said photodetecting means transversely across at least six stripes, means for sweeping said photodetecting means in a direction substantially parallel to said stripes, means for converting the output of said photodetecting means into a quantized signal, means for dividing said quantized signal into separate signals representing stripe widths and opening widths between stripes, means for accumulating stripe width and opening width signals associated with a particular exposure, and means for converting the accumulated stripe width and opening width signals into three signals representative of corrections to be made in the three photoexposing steps.
2. The apparatus according to claim 1, including means for providing signals related to target values of stripe width and opening width to said apparatus.
3. The apparatus according to claim 2, including means for taking the difference between said signals related to target values and the signals related to measured stripe width and opening width.
4. The apparatus according to claim 3, wherein said difference in signals is provided to said means for converting the accumulated stripe width and opening width signals, and the resulting signal represents deviation in center-to-center spacing between openings from a target value.
RCA 73,558
RCA 73,558
5. The apparatus according to claim 1, wherein said photodetecting means is a solid state line scanner.
6. The apparatus according to claim 1, wherein said sweeping means is a rotatable mirror.
7. The apparatus according to claim 1, including lens means for focusing light from said light source onto said photodetecting means.
8. The apparatus according to claim 7, including means for focusing said lens means in response to the amplitude of an output signal from said photodetecting means.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7900923 | 1979-01-10 | ||
| GB00923-79 | 1979-01-10 | ||
| US072,429 | 1979-09-04 | ||
| US06/072,429 US4498779A (en) | 1979-01-10 | 1979-09-04 | Automatic stripe width reader |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1147383A true CA1147383A (en) | 1983-05-31 |
Family
ID=26270182
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000342372A Expired CA1147383A (en) | 1979-01-10 | 1979-12-20 | Automatic stripe width reader |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1147383A (en) |
-
1979
- 1979-12-20 CA CA000342372A patent/CA1147383A/en not_active Expired
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