GB2143643A - Graphic recorder - Google Patents

Abstract

A graphic or chart recorder has a movable carriage 10 retaining pens 11, and an actuator 18. The actuator 18 and a key 19 are fixed to a block 16 which is slidable along a rod 14. The rod 14 may be turned about its axis to raise or lower the actuator 18 and key 19. The carriage 10 is provided with slots 25 for receiving the key 19, one slot adjacent each pen. In one angular position of the rod the actuator 18 holds the pen with which it is aligned against the recording surface and the key is engaged within a slot, for movement with the carriage. In another angular position the actuator and key are disengaged from the pens and carriage and the carriage may be moved to align a different pen with the key and actuator. In an intermediate angular position of the shaft the key is engaged in a slot but the actuator does not hold a pen against the recording surface. <IMAGE>

Description

SPECIFICATION Graphic recorder This invention relates to graphic or chart recorders.

Graphic recorders are known to the prior art. Typically, such recorders employ a pen or other similar recording element which is movable relative to a moving recording medium, the combined movement of the recording element and medium being controlled to produce a desired respresentation. The use of multiple pens for such purposes as multicolor plotting is known to the prior art.

An example of a multiple pen system is disclosed in United States Patent Number 3,401,401, issued September 1968 to Read, et al, for Multiple Pen Cartridge, which is hereby incorporated by reference. The disclosed Read embodiment employs four pens which may be independently chosen for color selection, for example. However, the selection of each pen requires the operation of a different pen-actuating device. Thus, the movable support for the pens must also support and move an independent actuating device for each pen. The overall mass of the moving support that results from the use of multiple pens and independent actuating elements has placed a practical limit of four pens on the Read technique.

An attempt to overcome the mass problems of multiple pen graphic recorders is disclosed in United States Patent Number 4,135,245 issued January 16, 1979 to Kemplin, et al for Plotter with Automatic Pen-changer, which is hereby incorporated by reference. The Kemplin system, like similar prior art systems, employs a pen repository, at which multiple pens are maintained, and a single pen recording head. The pen which is desired immediately for recording purposes is retrieved from the repository, after which the recording operation is initiated.

When a pen change is desired, the recording operation stops, and the recording head returns the pen it has utilised to the repository, where it also retrieves an alternative pen, according to instructions. While this does reduce the mass of the recording pen by the mass of those pens not used, together with their associated actuating and supporting structures, it increases the recording time by the amount of time necessary to return a previously utilized pen and to retrieve the pen that it is desired to use.

Systems meeting the general description of the two systems described above are in common use.

Since such systems are typically numerically controlled, each has qualities which frustrate the capabilities of the control systems. For example, heavier masses require heavier mechanisms for moving that mass, which may lead to difficulties in acceleration speed as well as precision. Greatertime requirements (i.e., for pen retrieval, for example) introduce a delay not required by the control system.

An improvement over the systems described above is disclosed in Patent Specification GB21271 53A. The system described in that specification has a multiple pen capability without the mass required for individual actuating systems for each pen. The multiple pen capability also eliminates the delays introduced by a pen retrieval operation.

However, even though a single actuator is em ployed, that actuator is carried with the moving elements such that its weight must be accommo dated. That actuator must be powered, requiring, in a preferred embodiment, an electrical connection with the moving elements. In addition, GB-2127153A discloses an embodiment which employs two positioning systems which must be controlled.

The present invention provides a graphic record ing system having a multiple pen capability with even greater mass reduction than that attained in the systems described in GB-2127253A. According to a first aspect of the present invention there is provided a chart recorder comprising: a carriage movable over a recording surface and carrying a plurality of pens; and an actuator for engagement with any of the pens, wherein the actuator, when aligned with a pen, is movable between a first position in which it is coupled for common movement with the carriage over the recording surface and holds the pen in a recording position against the recording surface and a second position in which it is not coupled to the carriage, whereby the actuator and the carriage are movable relative to one another so that the actuator can engage a different pen.

Preferably the actuator has a third position in which it moves with the carriage across the recording surface but does not cause a pen to record.

Preferably the recorder further comprises a key secured to the actuator for movement therewith, wherein the carriage is provided with a plurality of keyways, each keyway being associated with a pen, wherein when the key is within a keyway the actuator and the carriage are coupled for common movement over the recording surface.

The actuator may be mounted on a rod for sliding movement along the rod and for turning movement relative to the axis of the rod.

According to a second aspect of the invention there is provided, in a graphic recording system of the type wherein a plurality of recording elements are carried by a carriage, the carriage being movable in two directions along a path relative to a recording medium, and having means for selectively actuating said recording elements, by mechanical engagement, for recording on said medium, the improvement wherein said actuating means comprises: rod means having a longitudinal axis generally parallel to said path and supported for rotation, independently of said carriage, for rotation about said axis; actuator means carried by said rod means for rotation therewith while being movable along said rod means; and detect means selectively interlocking said actuator means and said carriage in predetermined relative positions.

Preferably, rotation of the rod is controlled by a dual-acting linear motion device such as a solenoid which acts on a rocker arm secured to the rod. In one solenoid position, the actuating arm is in mechanical engagement with a pen and interlocked to the carriage via the detent. In another solenoid position, the detent is out of locking engagement while the actuator arm is not in actuating mechanical engagement with a pen. In an intermediate position, the detent may interlock the actuator arm with the carriage while the actuator arm is out of actuating mechanical engagement with a pen to allow common movement of the actuating arm and carriage without a recording operation. The detent may be formed by slots within the carriage and a key commonly carried with the actuator arm into and out of a slot on the carriage.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 7 illustrates the interaction of the components forming a preferred embodiment of the present invention.

Figure 2 illustrates a side view of a portion of the embodiment of Figure 1.

Figure 3 illustrates a portion of the embodiment of Figure 1 with the pens removed for greater clarity.

Figure 4 illustrates the cooperation between that portion of the invention illustrated in Figure 2 and the pen carriage of Figures 1 and 3 and the pens illustrated in Figure 1.

Referring now to Figure 1, there is shown a pen carriage 10 having multiple pens designated 11. The pen carriage 10 may be supported in any convenient manner for movement in two directions along a path, as indicated by the arrows at 12. Typically, the medium on which it is desired to record is movable under the pen carriage in a direction perpendicular to the arrows 12, in known manner. Motion may be imparted to the carriage 10 via a band 13 which may be controlled in known manner.

A rod 14 has its longitudinal axis generally parallel to the path direction indicated by arrows 12 and is supported at its ends 15 independently of the carriage 10 for rotation about its longitudinal axis. A block 16 is carried by the rod 14 and is movable in both directions along its longitudinal axis, as indicated by the arrows 17.

In the illustrated embodiment, the rod 14 has a square cross-section and engages block 16 such that rotation of the rod 14 imparts a rotational force and movement to the block 16. Of course, other rod cross-sections and engagements with the block 16 which allow movement of the block 16 along the longitudinal axis of the rod while imparting a rotational force to the block on rotation of the rod may be employed.

An actuator arm 18 is carried by the block 16 and extends over the pens 11 of carriage 10 such that rotation of the rod 14 and block 16will cause the actuator arm 18 to engage and depress one of the pens 11 to actuate that pen for recording on the desired medium. A key 19 is also carried by the block 16 and will be discussed more fully below.

A rocker arm 20 is secured to the rod 14 and extends to the output shaft 21 of a linear motionimparting device 22. In a preferred embodiment, the linear motion device 22 is a dual action solenoid having extended, retracted and neutral positions of its shaft 21. The connection between the shaft 21 and rocker arm 20 may be of any convenient design known to the art.

As is apparent from Figure 1, extension of the shaft 21 induces a rotation of rod 14 and actuator arm 18 to a position where the arm 18 is out of engagement with any of the pens 11 of carriage 10.

Retraction of the shaft 21 induces the rotation of rod 14 and actuator arm 18 such that one of the pens 11 of carriage 10 may be engaged by the arm 18 to depress that pen and urge it into contact with a medium under the carriage 10. The cooperation between rod 14 and block 16, as weli as construction of the actuator arm 18 and key 19, is illustrated in side view in Figure 2.

Figure 3 is a view of a portion of the embodiment illustrated in Figure 1 with the pens removed to better illustrate the function of the key 19. The carriage 10 is provided with a plurality of slots 25, one slot per pen in the illustrated embodiment. On rotation of the rod 14 and the block 16, the key 19 may move into and out of any of the slots 25 with which it is registered. When the key 19 is within one of the slots 25, it acts as a detent to interlock the carriage 10 with the block 16. When interlocked, movement induced in the carriage 10 will cause the block 16 and, accordingly, the actuator arm 18 to move with the carriage 10. The slots 25, key 19 and actuator arm 18 are positioned relative to each other such that the positioning of a key 19 within one of slots 25 will position the actuator arm 18 over a pen 11 carried by the carriage 10.

Figure 4 illustrates the cooperation between the key 19 and the slots 25 and is a cross-section through any of the slots 25 as seen in Figure 3 with a pen 11 in position. The solid representation of block 16, actuator arm 18 and key 19 is that position that those elements will assume when the shaft 21 is in its extended position (see Figure 1). In this position the carriage 10 can be moved by the band 13whilethe block 16 remains stationary. Any one of the pens 11 can thus be selected by driving the carriage 10 to bring the selected pen into register with the key 19 and actuator arm 18. The neutral position of shaft 21 results in a positioning of the key 19 within a slot 25 with which it is in registration and a positioning of the actuator arm 18 over the associated pen 11.In this neutral position, shown in phantom in Figure 4, movement of the carriage 10 will result in a corresponding movement of the block 16 through the interlock resulting from the position of the key 19 within a slot 25. Thus, the carriage 10 and actuator arm 18 may be moved relative to the recording medium without recording thereon. The retraction of the shaft 21 from the neutral position will result in engagement of actuator arm 18 with its associated pen 11, a depression of that pen, and a recording on the medium on movement of either the medium or the carriage, or both.

The movement of the arm 18 resulting from the shift from the neutral to the retracted position of the shaft 21 is small, being limited by the movement of the key 19 downward in the slot 25 from the broken line position shown in Figure 4.

When the shaft 21 returns from the retracted to the neutral position it lifts the arm 18 back to the position shown in phantom in Figure 4. The arm 18 no longer urges the selected pen against the paper. Standard means (not shown), most commonly resilient means, causes the pen to rise from the recording medium and return to its original position in the carriage.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, more than one key 19 may be employed on the block 16 to engage multiple slots 25 associated with the pens 11. Other detent systems may also be employed. Further, while the present invention provides actuation of a recording element by mechanical engagement, other types of mechanical engagement may be employed within the scoope of the present invention. A dual-acting hydraulic cylinder may be substituted for the solenoid 22 while, as discussed above, other crosssections for the rod 14 may be employed.

What the present invention provides is a selective activation of one of a plurality of recording elements with the activating system being supported independently of the carriage for those recording elements.

It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims (14)

1. A chart recorder comprising: a carriage movable over a recording surface and carrying a plurality of pens; and an actuator for engagement with anycfthe pens,wherein the actuator, when aligned with a pen, is movable between a first position in which it is coupled for common movement with the carriage over the recording surface and holds the pen in a recording position against the recording surface and a second position in which it is not coupled to the carriage, whereby the actuator and the carriage are movable relative to one another so that the actuator can engage a different pen.

2. A recorder according to claim 1 wherein the actuator is movable, when aligned with the selected pen, to a third position between the first and second positions, wherein the actuator in the third position is coupled for common movement with the carriage over the recording surface but does not hold the selected pen in its recording position.

3. A recorder according to claim 1 or 2, further comprising a key secured to the actuator for movement therewith, wherein the carriage is provided with a plurality of keyways, each keyway being associated with a pen, wherein when the key is within a keyway the actuator and the carriage are coupled for common movement over the recording surface.

4. A recorder according to any preceding claim, wherein the actuator is mounted on a rod for sliding movement along the rod and for turning movement relative to the axis of the rod.

5. In a graphic recording system of the type wherein a plurality of recording elements are carried by a carriage, the carriage being movable in two directions along a path relative to a recording medium, and having means for selectively actuating said recording elements, by mechanical engagement, for recording on said medium, the improvement wherein said actuating means comprises: rod means having a longitudinal axis generally parallel to said path and supported for rotation, independently of said carriage, for rotation about said axis; actuator means carried by said rod means for rotation therewith while being movable along said rod means; and detect means selectively interlocking said actuator means and said carriage in predetermined relative positions.

6. The graphic recording system of claim 5 wherein said detent means comprises a plurality of slot means in said carriage in predetermined relationship with said recording elements and key means carried by and rotatable with said actuator means into and out of said slot means.

7. The graphic recording system of claim 5 or 6 wherein said actuating means further comprises means supporting independently of said carriage and actuator means for establishing the rotational orientation of said rod means.

8. The graphic recording system of claim 5 or 6 wherein said actuating means comprises means supported independently of said carriage and actuator means for selectively rotating said rod means between first and second angular orientations.

9. The graphic recording system of claims 6 and 8 wherein a recording element is mechanically engaged for actuation by said actuator means in said first rod means angular orientation and no recording element is mechanically engaged for actuation by said actuator means in said second rod means angular orientation, said key means being in said slot means in said first rod means angular orientation and out of said slot means in said second rod means angular orientation.

10. The graphic recording system of claim 9 wherein said means for selectively rotating said rod means comprises means for selectively rotating said rod means to a third rod means angular orientation intermediate said first and second rod means angular orientations, said key means being in said slot means with no recording element engaged for actuation by said actuator means in said third rod means angular orientation.

11. The graphic recording system of any of claims 5 to 10 wherein said actuator means comprises actuator arm means mechanically engageable with said recording elements.

12. The graphic recording system of any of claims 8 to 10 and 11, as appendant to any of claims 8 to 10, wherein said means for selectively rotating said rod means comprises rocker arm means secured to said rod means and dual-action linear motion means having a neutral position operative on said rocker arm means.

13. The graphic recording system of any of claims 5 to 12, wherein said actuator means is moved along said rod means by a force imparted by said detent means.

14. A chart or graphic recorder substantially as hereinbefore described with reference to the accompanying drawings.