US 3742833 A
Apparatus for optically encoding an item and verifying same, generally including a rotatable index table for sequentially accepting items and carrying each item to a first station where direct printout photosensitive material is applied to a predetermined portion of the item by spraying, to a second station where an optical code image is formed by ultraviolet radiation impinging on a plurality of piezoelectric elements and projected onto the photosensitive material and printed out thereon. The item is then rejected from the table and preferably read at a verification station to verify the accuracy of the encoded data.
Description (OCR text may contain errors)
United States Patent [1 1 Sewell et a1.
SYSTEM FOR OPTICALLY ENCODING AN ITEM AND VERIFYING SAME Inventors: John M. Sewell; Lawrence J.
Matteson; Stuart F. Ring, all of 901 Elmgrove Road, Rochester, N.Y. 14650 Filed: June 14, 1971 Appl. No.: 152,917
US. Cl 95/12, 95/1 R, 310/85,
3l0/8.6, 346/107 R Int. Cl. G03b 29/00 Field of Search 95/ 12, 1 R;
References Cited UNITED STATES PATENTS 5/1967 Fiore 95/1 R 9/1890 Enjalbert 95/14 X [451 July 3, 1973 3,587,856 6/1971 Lemelson 346/74 MP X 3,465,317 9/1969 Rabinow et al. 346/74 MP X Primary ExaminerRobert P. Greiner Attorney-W. H. J. Kline et a1.
[ 57] ABSTRACT Apparatus for optically encoding an item and verifying same, generally including a rotatable index table for sequentially accepting items and carrying each item to a first station where direct printout photosensitive material is applied to a predetermined portion of the item by spraying, to a second station where an optical code image is formed by ultraviolet radiation impinging on a plurality of piezoelectric elements and projected onto the photosensitive material and printed out thereon. The item is then rejected from the table and preferably read at a verification station to verify the accuracy of the encoded data.
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SYSTEM FOR OPTICALLY ENCODING AN ITEM AND VERIFYING SAME BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a system for encoding an image upon an item and for verifying the image and more particularly to a system for producing an encoded image by optical means wherein the image is formed by modulating a beam of ultraviolet radiation by means of piezoelectric elements and a permanent record of the image is produced on direct printout, photosensitive material which is applied to the item.
2. Description of the Prior Art In many applications it is desirable that an optical code be applied to an item so that the coded information may be used to subsequently control various operations relating to the item, for example, the handling and sorting of items such as letters, checks, invoices, or the like. It is desirable to optically encode on the item information recorded on the document, such as the zip code or the like. The optical code may be read more easily than the information imprinted on the document and, therefore, contribute to the reliability and accuracy in handling the item. In such applications, it is desirable that the code formed on the item be done so rapidly, accurately, and with little or no further processing steps. Present systems utilizing phosphorescent ink are unsatisfactory since the ink tends to blur and tends to diffuse over an area wider than the area it is desired to print the bar code. In order to attain accuracy, therefore, it has been necessary to utilize impact printing techniques which are relatively slow and require repeated maintenance of the printing members which tend to wear out quickly.
SUMMARY OF THE INVENTION It is thus an object of the present invention to provide a system for optically encoding on an item information relevant to the subsequent processing of the item which is efficient and economical and which requires a minimum of maintenance.
It is a further object of the present invention to provide a system for encoding an optical bar code on an item wherein further processing beyond imaging of the bar code on the item is unnecessary and the minimum number of steps for producing the bar code on the item are needed.
In general the system according to the present invention comprises means for applying a coating of photosensitive direct printout material to a portion of an item; means for modulating a beam of radiation through piezoelectric elements interposed in the path of the beam according to a predetermined pattern to produce a modulated beam corresponding to the bar code to be produced on the item; and means for projecting the modulated image onto the photosensitive area to produce a direct printout image of the bar code on the item. A verifier is preferably provided for reading the imprinted bar code and comparing it with the signals used to control the piezoelectric modulator to verify the accuracy of the imprinted code. In a preferred embodiment, letters are fed to a four-sided index tray which carries individual letters to a spray station where direct printout photosensitive material is applied to a letter at the spray station by means of a nozzle which moves relative to the letter to spray the material on the letter in a predetermined area. Thereafter, the letter is rotated to a writing station comprising a source of ultraviolet radiation, a plurality of piezoelectricreeds disposed in the path of the beam of ultraviolet radiation, a shutter mechanism for thermally shielding the piezoelectric modulation mechanism from the heat of the ultraviolet radiation source, except during exposure and for providing a controlled exposure time and an optical system preferably comprising a quartz lens and a lens system which projects the ultraviolet optical bar code image onto the sprayed area of the letter.
BRIEF DESCRIPTION OF THE DRAWINGS In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawing, in which:
FIG. 1 is a perspective view of a preferred embodiment of apparatus according to the present invention for optically encoding an item such as a letter and for verifying the encoded information;
FIG. 2 is a partial plan view of the apparatus of FIG.
FIG. 3 is a partially sectional elevational view showing details of the registration mechanism of FIG. 1;
FIG. 4 is a partially sectional perspective view of the letter clamping mechanism of FIG. 1;
FIG. 5 is a partially sectional perspective view of the letter ejection mechanism and pinch belts of the apparatus of FIG. 1;
FIG. 6 is a partially sectional perspective view of the letter stop mechanism of FIG. 1;
FIG. 7 is a perspective view illustrating the basic elements of an optical bar code projection means which may be used in the apparatus of FIG. 1;
FIG. 8 is a partially sectional top plan view of structure embodying the elements of the projection means of FIG. 7;
FIG. 9 is a partially sectional elevational view of the projection means of FIG. 8;
FIG. 10 is a partially sectional perspective view of the shutter mechanism of the projection means of FIGS. 8 and 9;
FIG. 1 l is a partially sectional perspective view of the piezoelectric light modulation mechanism of the projection means of FIGS. 8 and 9;
FIG. 12 is a partially sectional perspective view showing the piezoelectric elements of the mechanism of FIG. 11 in greater detail;
FIG. 13 is a partial elevational view showing the piezoelectric elements of the mechanism of FIG. 11 in the at rest position or bent either into or out of registration with a light slot;
FIG. 14 is a schematic view illustrative the operation ofa piezoelectric element of the mechanism of FIG. 11;
FIG. 15 is a partially sectional elevational view schematically illustrating a preferred form of optical bar code reader according to the present invention;
FIGS. 16-19 are schematic diagrams of a preferred form of electrical circuit to be used in conjunction with the reader of FIG. 15;
FIGS. 20 and 21 are perspective views illustrating alternate embodiments of optical bar code projection means;
FIG. 22 is a schematic illustration of a letter showing the optical bar code for the Zip Code in the mailing address;
FIGS. 23 and 24 are tables respectively illustrating the decimal to binary relationship and the decimal to optical binary bar code relationship.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures, there is shown a preferred embodiment of apparatus according to the present invention for optically encoding an item such as a letter and for verifying the accuracy of the encoded information. As shown in FIG. 1, apparatus 30 generally comprises an index table 32, a letter load and unload station 34, a photosensitive material application station 36, an optical bar code projection and exposure station 38 and an optical bar code reader and verification Sta-- tion 40.
More specifically, apparatus 30 comprises a base member 42 upon which is mounted index table 32. Index table 32 comprises a rotatable tray 44 having a plurality of pockets 46 for accepting items such as letters 56 upon which an optical bar code is to be imprinted. As shown, pockets 46 may comprise four arranged in a square about the periphery of tray 44, each pocket 46 being formed by side walls 48 and 50, end wall 51 and a plurality of rollers 52 journaled in bearings 54 respectively on the lower portions of members 48 and 50. Rollers 52 are adapted to support a letter 56 in pocket 46, to facilitate registration at station 36 and to permit rapid ejection thereof at station 34.
Index tray 32 is adapted to be rotated between a plurality of stations 34, 36, and 38 at which various operations are performed on an item supported within a pocket 46. At station 34 an item such as a letter 56 is fed either positively or by gravity to a pocket 46 where further vertical movement is restrained by rollers 52.
As shown more clearly in FIG. 4, a clamp 190 is provided for each pocket 46 to hold a letter 56 therein. Clamp 190 is hingedly mounted on the rear of wall 50 by brackets 192 and projects through a slot 194 in wall 50. Clamp 190 is normally spring biased to a letter holding position by means of a suitable spring such as compression spring 196 bearing against member 198 of clamp 190. Member 198 projects below rollers 52 and is engageable by a solenoid mechanism 200 to move clamp 190 into an unclamping position against the bias of spring 196.
After an item such as letter 56 has been loaded into pocket 46 at station 34, solenoid mechanism 200 is deactivated to permit clamp 190 to clamp letter 56 and index table 32 is rotated to station 36. Station 36 comprises a registration mechanism 58 and a photosensitive material application mechanism 60. Registration mechanism 58 is adapted to position letter 56 relative to mechanism 60 so that suitable photosensitive material may be applied to a predetermined area of letter 56.
Registration mechanism 58 comprises a continuously driven conveyor belt 64 mounted on members 66, belt 64 being swung into and out of engagement with rollers 52 to drive the rollers. As table 32 is indexed to station 36, a suitable cam mechanism 69 depresses mechanism 58, thus allowing rollers 52 to clear belt 64.
After table 32 has stopped at station 36, cam mechanism 69 forces conveyor belt 64 mounted on members 66 into engagement with rollers 52 to move a letter positioned in tray 46 to the right as shown in FIGS. 1 and 3 in order to bring letter 56 into registration with a slot 68 in wall 48.
As shown in FIG. 6 the letter isstopped by a suitable stop member 70 which is controlled to swing into and out of engagement with slot 72 formed by members 48 and 50 of pocket 46. Control of stop 70 is by suitable control circuitry not shown which is synchronized with the rotation of table 32 so that as a pocket 46 is indexed around to station 36, stop 70 is swung out of the path of rotation of tray 32 until the tray has come to a rest and registration mechanism 58 has been engaged.
After a letter 56 has been suitably registered with respect to slot 68 at spray station 36, mechanism 60 is activated to apply by spraying onto the area of letter 56 which is exposed by slot 68, a coating of a photosensitive material which requires little or no further processing once it has been exposed to suitable radiation to develop a coded image in the material. Preferably, such a material is not sensitive to light in the visible spectrum and comprises a print-out negative working,
ultraviolet-sensitive material. A number of such materials are suitable for this application such as polyacetylenic compounds such as those disclosed in US. Pat. No. 3,501,302 of Foltz issued Mar. 17, I970. In general, the material selected should preferably be negative-working i.e., give a colored image in areas exposed to suitable radiation; have high resolution; have high speed; be relatively stable under normal daylight and artificial lighting; be sensitive within a relatively narrow range of the nonvisible spectra, preferably the ultraviolet; require no processing after exposure; and be readily applicable by a variety of techniques such as spraying or the like at a reasonable cost.
Other suitable photosensitive materials which require no processing after exposure to a suitable image may also be used.
As shown more clearly in FIGS. 1 and 2 mechanism 60 comprises a spray gun 73 mounted from rails 74 and 75 by means of carriage 76. Preferably, the suitable photosensitive material is supplied to gun 73 through suitable conduits 78 which communicate with gun 73 through carriage 76 and hollow support member 80.
Preferably, the spray gun 73 sprays suitable radiation sensitive'material onto the letter through slot 68 as gun 73 is returned from the position shown in dashed lines as at 82 in FIG. 2 to the at rest position as at 84 out of the way of the circle of rotation of table 32. It will be understood, however, that the spraying of letter 56 in tray 44 could also be accomplished during the movement of the gun 73 from position 84 to 82. Alternatively, gun 73 might be mounted for rotation to spray the letter in an arcuate path. In such circumstances, the carriage and rail mechanism shown in the drawing would be replaced by a suitable rotatable drive mechamsm.
After the predetermined area of letter 56 has been sprayed with a coating of suitable photosensitive material, index table 32 is indexed around to exposure station 38. Previously thereto stop mechanism has been rotated out of the way of tray 32 so that the index tray 32 may be moved without any interference from stop 70.
At exposure station 38 a suitable encoded bar code image is projected upon the area of letter 56 which has been sprayed with suitable photosensitive material.
FIG. 7 schematically illustrates apparatus for forming and projecting an optical bar code image onto such area. Assuming that a material sensitive to ultraviolet radiation has been sprayed upon a letter 56, apparatus 89 includes a source 90 of ultraviolet radiation, a modulator 92 for modulating the beam produced by source 90 according to a predetermined bar code pattern, and a projection lens assembly 94 for projecting the modulated ultraviolet radiation beam onto letter 56. Source 90, for example, may comprise a suitable ultraviolet lamp 96 enclosed within a sleeve 98, lamp 96 being cooled by a suitable blower 100 in communication with sleeve 98. Sleeve 98 is preferably of a material such as quartz, which effectively filters any radiation from lamp 96 outside of the appropriate ultraviolet region.
Referring now to FIGS. 8 and 9 there is shown in greater detail a preferred embodiment of projection apparatus according to the present invention which incorporates the elements shown in FIG. 7. As shown, apparatus 89 comprises a base 102 upon which is mounted lamp 96, a quartz sleeve 98 surrounding lamp 96, a lamp cooling mechanism 104 in communication with sleeve 98, a shutter assembly 106 for controlling the amount of radiation projected from lamp 96, a piezoelectric commutator or modulation assembly 108 for modulating the beam of light radiated by lamp 96 past shutter assembly 106 and a projection system 94 comprising lenses 110 and 112 and a diaphragm 114.
Since ultraviolet radiation can catalyze chemical reactions in airborn impurities such as oil vapors dispersed in the air which then build up as a residue on optical surfaces and the like, it is desirable that the cooling system 104 for the illuminator assembly and shutter mechanism be filtered using absorbtion-type media. It is also desirable that the projection system 94 be mounted within a sealed housing such as housing 113 having sealing plates 116 and 118 at either end thereof, so that the optical elements of the projection system are protected from water vapor.
Referring now to FIG. there is shown in greater detail a preferred embodiment of shutter mechanism according to the present invention. As shown, shutter mechanism 106 comprises a primary shutter consisting of a drum 122 having a slot 124 formed therein. Drum 122 is mounted for rotation in bracket 126 and is driven by a gear drive 128 by means of commutator step motor 130. The primary shutter 122 will expose the full bar code when radiation from lamp 96 is transmitted through slot 124. The shutter mechanism 122 also acts as a thermal barrier to prevent the heat of lamp 96 from affecting commutator mechanism 108.
A secondary shutter mechanism is also provided which may, for example, comprise blades 132 and 134 mounted for sliding movement on plate 136. Blade 132 may, for example, be manually actuated by linkage 138 and blade 134 may be manually actuated by linkage 140. By means of the blades 132 and 134 selected fields of the bar code may be imaged onto a letter through manual selection of the appropriate blades 132 and/or 134.
Referring now to FIGS. 11-14, there is shown in greater detail the piezoelectric commutator or modulation mechanism 108 according to the present invention. As shown mechanism 108 comprises a slotted mask 142 mounted between members 144 and 146 respectively having recesses 145 and 147. A plurality of piezoelectric elements or reeds 148 projecting into recesses 145 and 147 are mounted by members 144 and 146 alternatively on either side of mask 142. Elements 148 are provided with upwardly projecting portions 150 which partially cover slots 152 in mask 142.
This is more clearly shown in FIGS. 12 and 13' wherein reeds 148 are shown alternately disposed on either side of mask 142. For example, reeds 148a, 148e, 148e and 1483 may be disposed on the rear side of mask- 142 and reeds 148b, 148d, and 148f may be disposed on the front side of mask 142. Portions of reeds 148 are shown as partially covering slots 152 of mask 142 and in their at rest position cover the lower righthand portion of slots 152 as portions 150a of element 148a is shown covering the lower right-hand portion of slot 152a. Since it is desired that a slot of light either the full height of slot 152 or half the height of 152 be projected to form a half bar or full bar in the photosensitive material supplied to a suitable letter, reed 148 is so controlled that portion 150 thereof will either be bent into registration with the lower half of slot 152 as more clearly shown by portion 150d of element 148d covering the lower half of slot 152d or be bent entirely out of registration with the lower half of slot 152 as shown more clearly by portion 150f of element 148fcompletely uncovering the lower half of slot 152f.
Stops 154 are provided on either side of piezoelectric elements 148 to limit the lateral flexing of elements 148.
FIG. 14, shows schematically the operation of element 148. Preferably, element 148 comprises a laminate of flexible piezoelectric strips 156 and 158 disposed on either side of a flexible metal strip 160, which may, for example, be made of brass. Disposed at the base of strips 156 and 158 are electrodes 162 and 164 to which is applied to a d.c. voltage as from a reversible d.c. source 166. When it is desired to bend the piezoelectric element in one direction or the other, a voltage of suitable polarity is applied to electrodes 162 and 164 from reversible source 166.
By suitably controlling a series of piezoelectric elements 148 disposed in registration with slotted mask 142, a beam of radiation, such as ultraviolet light from lamp 96 transmitted through the mask may be modulated according to a predetermined pattern and the modulated beam projected upon a suitable photosensitive area sprayed on an item such as a letter to produce an image on the area which corresponds to the desired predetermined modulated image. In such manner, an optical binary bar code which is representative of mailing information written on the letter may be encoded in a preselected area of the letter for subsequent handling and processing of the letter through the reading of the code by an optical bar code reader.
After an appropriate bar code has been imaged onto the letter supported at station 38, the letter is carried by index table 32 back to station 34 where it is ejected from pocket 46 by means of ejection mechanism 62. This is shown more clearly in FIGS. 1 and 5 wherein ejection mechanism 62 comprises an ejection member mounted on belt 172 which is journaled on pulley 174 driven by a suitable drive motor 176.
Member 170 is adapted to clear slot 177 formed between members 48 and 50 above wall 51 to push letter 56 to the right as shown in FIG. 5 where letter 56 is gripped between pinch belts 178 and 180 to carry it past slot 182 in verifier plate 184 where it is read by optical binary code reader or verifier 186.
Referring now to FIG. 15, there is shown a preferred embodiment of optical binary code reader 186. As shown, reader 186 comprises a housing 210 having front wall or plate 184 with a slot 182 therein. Mounted within housing 210 is a lamp 212 having a reflector 214 for illuminating the bar code on letter 56 as it is moved past slot 182. The reflected image of this bar code will be transmitted through slot 182, reflected from mirror 216 and imaged onto photodiode array 218 by lens system 220.
Photodiode array 218 preferably comprises a linear array of approximately 50 photodiodes which scan incremental segments of the optical bar code on letter 56. As will be described in greater detail hereinafter, each segmental scan detected by diode array 218 is in turn scanned by suitable electronic switching means in such manner that each diode in the array is sequentially interrogated to determine its signal level. The electronic scan rate is preferably such that each bar is scanned at least three or four times. A full-bar half-bar, no bar determination will then be made by measuring the length of bar on each scan and taking a vote on the scan determinations.
Referring now to FIGS. 16-20 there is shown schematically an electronic system detecting and comparing the optical bar code data read by reader 186.
FIG. 16 schematically shows a master clock 228 which controls all the events in the reader. As shown a clock 230 running at twice the shifting frequency of the photodiode array toggles flip-flop 232 and is gated with the complementary outputs of flip-flop 232 in gates 234 and 236 to produce two non-overlapping pulse trains of opposite phase respectively through operational amplifiers 238 and 240. These pulse trains are respectively pulse shifted by transistors 242 and 244 to provide the 01 and 02 clock signals required by photodiode 218.
In addition, a 6-bit binary counter controlled by flipflop 232 is decoded by gate 246 and by means of operational amplifier 248 and level shifting transistor 250 provides a data pulse overlapping every 64th 01 pulse.
The photodiode array and associated circuitry is illustrated in FIG. 17. Each data pulse is used by photodiode 218 to set the first stage of its internal shift register and is shifted down the array by the 01 and 02 pulse trains from master clock 228. As the data bit is shifted by each location of the register it causes the contents of the corresponding photosensitive element to be sampled and to appear on the video output. Threshold amplifier 252 compares the video output with an automatically generated reference signal (representative of the reflectance of the individual envelope) to generate a binary signal which is high for dark areas and low for light areas. The threshold output of threshold amplifier 252 is integrated by operational amplifier 254.
At the conclusion of one scan of the 50 elements of photodiode 218 the voltage appearing on the output of amplifier 254 represents the integral of the bar length perceived as darkened (printed) during that scan. This voltage is monitored by threshold amplifiers 256 and 258. The threshold of amplifier 256 is twice that of amplifier 258. If the area of the envelope being examined contains a full bar, the integral will be large, and at the conclusion of a scan both the high-threshold and lowthreshold signals will be high. A half bar will result in a high on the low threshold output only, and the absence of a bar will result in neither output reaching the high state.
As the last element of the photodiode is sampled, a pulse appears on the Data-I output of photodiode 218.
This pulse is amplified by amplifier 260 and used t sample the states of the highand low-threshold amplifiers 256 and 258 to determine whether the scan just completed was of a full bar, a half bar, or no bar. The Data-ll output of photodiode 218 is used to latch operational amplifier 262 with its output in the high state. This causes N-channel FET 264 to conduct and discharge integrator storage capacitor 266 restoring a zero initial condition to the integrator. Pulse 64, which is the Data Input pulse for the next scan of the diode 218, causes amplifier 262 to latch in the low state again and transistor 264 becomes nonconducting. Amplifier 254 then begins integration of the next scan.
Processing of the high and low threshold signals to identify full bar, half bar and no bar regions is performed by logic illustrated in FIG. 18. Two shift registers are used; Register 270 to store the low-threshold samples and register 272 to store the high-threshold samples. The sample pulse generated by amplifier 262 of FIG. 17 shifts registers 270 and 272 and causes each to store an up-to-date display of the results of the last four scans of photodiode 218. The criteria used to identify characters are: p
a. A full bar is characterized by a three out of four majority of scans in which both the high-threshold and low-threshold bits are high.
b. A half bar is characterized by three out of four scans in which the low-threshold bit is high and the high-threshold bit is low.
c. No bar is characterized by three out of four scans in which both bits are low.
The majority voting gates used to recognize a halfbar character are shown in FIG. 18 for illustration. The gating for full bars and blanks is similar, differing only in connection to the shift register outputs. Gate 274 recognizes the condition in which the last three of the four scans stored all agree that a half bar was read. For this condition to exist, the contents of the first three stages of the high shift register are all zero and the contents of the first three stages of the low-shift register are all one. All six inputs to gate 274 are then one and the output of gate 274 goes to zero, indicative of recognition of a half bar character. Thus the shift register state denoted HI-IH has been recognized and correctly interpreted as a half bar. (The X in this notation indicates an arbitrary or dontt care state which may be a blank b, a half bar h, or a full barf.)
Three other three-out-of-four shift register conditions are possible which are also valid indications of a halfbar reading. They are:
h X h h h h X h The first condition, X h h h, is trivial as it is identical to the h h h X condition recognized by G1, but displaced in time by one scan. the other two conditions are valid and unique indications of a half bar and are recognized by gate 276 and gate 278 in the same manner as described above for gate 274. The output of the three gates are wired together so that a character recognition by any one of the three causes the half bar output to go low.
Identical sets of gates (not shown) recognize full bar and blank characters. The significant states of the three character outputs thus generated are:
a. All high; indicates a noisy signal or an intermediate state between two of the states described below.