US2124802A - Device for observing color register indications of color prints discharged from a multicolor press - Google Patents

Description

July 26, 1938. R 51 WALLACE 2,124,82

DEVICE FOR OBSERVING COLOR REGISTER INDICATIONS OF coLoR PRINTS DISCHARGED FROM A MULTICOLOR PRESS Fild Jan. 15, 1.936

Patented July 26, 1938 UNITED STATES PATENT OFFICE Richard Edgar Wallace, Toronto, Ontario, Canada Application January 13, 1936, Serial No. 58,832

2 Claims.

My invention relates to improvements in devices for observing color register indications of color prints discharged from a multicolor press, and the object of the invention is to devise a simple device whereby magnified images of color register indications of a succession of prints travelling from the press in a linear direction may be each successively retained momentarily in a stationary position to form a continuous picture before the eye of an observer and thereby more quickly detect when and to what extent the colors become out of register and in consequence saving, to a great extent, the loss due to the printing of defective prints, that is prints in which the colors do not perfectly register, and it consists essentially of the arrangement and construction of parts all as hereinafter more particularly explained.

Fig. 1 is a vertical sectional view through my device.

Fig. 2 is a plan sectional view.

In the drawing like letters of reference indicate corresponding parts in each figure.

I indicates the casing, the lower portion of which is cylindrical, the side walls of the casing I and I" flaring upwardly and provided with front and rear walls forming at the top a rectangular' opening 2 in which a window glass 3 may be secured. 5 is a line which indicates the direction of travel of the color prints after passing off the press, the prints themselves being indicated by the broken line 6.

The inner side 2 of the casing l is completely cylindrical and is provided with an inner wall 2 and an outer wall 2 I is a rock shaft which extends through the wall 2 into proximity with the wall 2 at one end and with the wall 3 at the opposite end. In the walls 2 and 3 are held point bearings 8 and 9 fitting into conical recesses formed in the ends of the rock shaft 1 so as to turnably support it. The upper portion of the rock shaft 1 is cut away as indicated at I so as to form a flat surface extending just below the centre of the shaft. On this surface is secured a reflecting mirror l0 so that the reflecting face of the mirror is located exactly on the centre line of the rock shaft.

I2 is a cam shaft extending through the wall 2 and journalled in the walls 2 and 3 The cam shaft I2 is driven from any suitable source and is provided at one end with a fly wheel l3. ll is a cam secured to the cam shaft l2, the periphery of such cam being somewhat spiral in form so as to provide a major and a minor radius but microscopically varied from the true spiral. I5 is an arm which is secured to the rock shaft 1 and is provided with a ball end I5 bearing upon the periphery of the cam l4 and held in contact therewith by a coil spring ll secured to the rock shaft 1 at one end as indicated at I I and to a suitable portion ofthe casing at the opposite end as indicated at H. As the cam revolves it alternately forces the arm l5 away from the centre of the cam and at the point of greatest radius releases it so that it is brought quickly to the minor radius. The cam I4 is so formed that it gradually tilts,

by means of the arm Hi, the mirror in so that its tilting travel corresponds with the travel of the color prints 6 passing over the window orifice 3.

If the prints travelled in a circular path as illustrated by the broken line A, B, C, equal amounts of the are A, B, C, through which they pass would correspond to the same number of equal amounts of the mirrors rotation.

For the sake of simplicity in explaining the variation between the tangent and arc, I am, in this case, leaving out the doubling effect of the angle of incidence and reflection. It is to be noted, however, that the eye viewing the mirror along the line 24 when the mirror is in its medial position will view therein the point B in the arc A-C, this point and the point B in the line A'C being coincident and therefore equally distant from the axis of the mirror. As the mirror is rotated uniformly, uniform portions indicated by lines D of the arc A-C' are viewed in the mirror simultaneously with corresponding portions on the line AC. The corresponding portions of the line AC instead of being uniform become greater as the movement of the mirror carries the view point away from the point Baforesaid. A ray of light leaving the point A striking the surface of the mirror when in the dotted position is reflected in a path coincident with the line 24 and the mirror is kept at all times in such a position that the reflections from the moving print or register mark will always pass along this line. As the travel of the print is tangent to the arc, the portions indicated by lines D become smaller in comparison to the aforesaid equal portions indicated by lines D of the mirrors rotation as the print approaches the point.B from point A and again become larger as the print leaves the point B and approaches the point C. Therefore, theperiphery of the cam H is so designed as to rotate the mirror a minimum distance when the register mark is at the point A and to increase this distance gradually until'the movements of the mirror and register mark are equal at the point B and to-again decrease this distance until the point C is reached.

I eye of the observer.

i6 is a tube forming a viewing orifice in which are located the lenses H and it, the centres of which are directly opposite the centre of the mirror It. It will thus be seen that as the color prints travel in the direction of the arrow and the images thereof are reflected to the eye, the tilting movement of the mirror will hold such reflected image in an apparently stationary position before the eye, the angle of incidence and the angle of reflection remaining equal throughout the movement.

When the major radius of the cam M has tilted the mirror id to the full line position shown in Fig. 1, the mirror is released so that it immediately springs back by means of the spring I I to its normal or dotted line position. It is essential during this change that the eye will not be subject to this movement and in order to prevent this, I have provided a shutter which is interposed between the lenses ll and the mirlocated directly on the centre line of vision indicated by the dotted line 24. This blade being of thin material stops very fewlight rays but on turning gives twice as fast a cut on, i. e. each side immediately and simultaneously cuts off the light path. 25 is a pin projection extending from the enlargement 22 into the recess 28 and 26 is a spring finger which extends from a cylindrical body 211 secured to the cam shaft I2. 28 and 23 are segmental recesses which are formed in the cylindrical portion 2l of the bracket 2! and 29 is a pin which extends from the enlargement 22 of the shutter into the segmental recess 28.

When the arm comes to the highest point of the cam M, the spring finger 26 is turned to engage the pin 25 to force it against the opposite end of the recess 28 to swing the shutter 23 definitely to the vertical or dotted line position shown in Fig. 1. When in this position, the view of the mirror is entirely obstructed from the Also when in this position the cam arm [5 drops from the major radius of the 0am! to the minor radius and as soon as this is accomplished the finger 26 passes the pin 25 when in' the dotted position shown in Fig. 1 so as to release the rock shaft 9 to permit it being carried back to its normal position by the spring 20 which is placed under into tension by the closing of the shutter. The return movement is limited by the pin 23 engaging the end of the recess 28.

In order to automatically correct the focus during the movement of the mirror, I mount the lens IT in a movable cylindrical carriage l1 which is provided with a lug ll extending through a slot IB in the tube i6.

30 is an eccentric which is secured to the cam shaft I2 and is provided with a surrounding varies and for this reason the focus must be adjusted during the paper travel before the mirror.

33 is a tubular arm which extends from the main tube 86 and in this arm is located a light source 36, the rays of which pass through a lens 35 and are collimated by the reflecting mirror 36 which is provided with a central orifice 37 located on the centre line of vision between the lenses ill and it said mirror directing an intense light onto the mirror Ml and from thence to the image or color register indication. The lenses ill and 35 are so designed as to direct a spot of intense light on the color indication as its image is reflected on the mirror and the image is, at the same time, enlarged by the lenses ll in conjunction with the ocular lens l8.

From this description it will be seen that I have devised a very simple device which, by the action of the mirror ill, holds the reflection of the color register indication which is usually in the form of in a stationary position before the eye so that it can be readily observed in a magnified form and any variations from the register readily observed and the adjustments made the, results of which can be immediately seen before a large amount of imperfect prints have been run oif the press and the wastage which has always taken place through this defect thereby saved.

At the point of focus of the objective lens may be placed crossed hair lines such as provided in a microscope and by this means the operator can quickly observe how far the print is out of register by measuring the degree of error and thereby enabling him to make his correction quickly and eliminating all guess work. This device also permits the paper being observed under actual working conditions which are modified by tension, speed and the effect of dampness or change of temperature, drafts etc.

'The lens ll serves two purposes. First, it is the objective lens for enlarging the image to be further enlarged by the ocular lens l8. Second, it acts as a converging lens to concentrate the light-rays coming from the condensing lens 35 so that there will be a small intense spot always concentrated on the moving image.

With a stroboscope the image is only seen for the barest fraction of time, being lost the greater part of the time. With my device the image is seen for the longest time and lost-to view for the briefest fraction of time.

What I claim as my invention is:

1. A device for observing color register marks upon a printed sheet moving in a linear direction, comprising a rotatably mounted reflector adapted to reflect the image of the register marks in a constant line of direction during a given length of movement of said marks, lenses interposed in the line of the reflected image, a reflector interposed in the line of the reflected image having an opening therethrough, means directing a beam of light onto said perforated reflector to be reflected onto the moveable reflector andfrom thence to the printed sheet to illuminate the register mark throughout its path of movement, means for operating said rotatable reflector to follow the movement of the register mark on the printed sheet and direct an image of said mark in a constant line of direction through said lenses and through the opening in said perforated reflector.

2. A device for observing color register marks upon a printed sheet moving in a linear direction, comprising a rotatably mounted reflector,

memos: 3

the lenses for operating such lenses in unison with the movement of said reflector for maintaining a constant focus of said image, and means ior directing a beam of light on to said reflector to illuminate the register mark throughout 5 its path of travel.

RICHARD EDGAR WALLACE.

Images