Abstract: Perforations are formed at predetermined positions of a rolled record paper to facilitate cut out of the record paper at the predetermined positions. A perforating wheel for forming the perforations is made of a plurality of materials to enhance durability and reduce a cost. The positions of the perforations on the record paper are set at front and rear edges of a recorded image or at an area between recorded images so that the record paper is properly cut out.

Abstract: An improved image building apparatus for building color image on paper by transfering thereto a plurality of coloring agents on thermal transfer ribbon by means of a thermal head while reciprocably conveying paper by rotating a platen is disclosed. To assure that paper is firmly held on the surface of the platen the apparatus includes two groups of thrust rollers and a printing head actuating mechanism for displacing the printing head toward and away from the platen. Thus, reciprocably movable paper is brought in close contact with the surface of the platen at least at two points under the effect of thrust force given by the thrust rollers and the printing head without occurrence of dislocation of color transference and the area where no image is built at both the leading and tail ends of paper can be minimized.

Abstract: An X, Y plotter particularly adapted to use both cut paper and strip paper. A driven roller provides motion of the paper back and forth according to one signal. A moveable pen block containing the pen is moved transverse the path of the paper in response to the second signal, thus providing controlled motion in the X and Y directions. According to one aspect, an idler roller is provided parallel to the driven roller around which an endless belt is disposed to be driven in combination with the drive roller by two pairs of rows of sprockets on the driven roller adapted to mate with holes provided therefor in the belt. Cut paper temporarily attached to the belt with drafting tape or the like is moved beneath the pen for plotting purposes. The inner row of sprockets is adapted for engaging holes in strip paper for moving it beneath the pen.

Abstract: A printer such as a thermal printer includes a reversible motor, a paper feed driver angularly movable through a desired angle in response to operation of the motor, a paper feeder rotatable for feeding a sheet of paper, and an electromagnetic clutch operatively connected between the paper feed driver and the rotatable paper feeder. The electromagnetic clutch comprises a first yoke, a second yoke disposed in confronting relation to the first yoke normally in spaced relation thereto, and an exciting coil wound around one of the first and second yokes, the first yoke being coupled to the paper feed driver, the second yoke being coupled to the rotatable paper feeder, the arrangement being such that when the paper feed driver is turned in a direction to feed the sheet of paper, the exciting coil is energized to attract the first and second yokes magnetically to each other for thereby causing the paper feed driver to rotate the rotatable paper feeder to feed the sheet of paper through the electromagnetic clutch.

Abstract: A postage meter which includes a thermal print head for printing indicia, postal value, and the like is disclosed. In accordance with the invention, thermal elements in the thermal print head are electronically pulsed in appropriate serially timed patterns to provide a complete thermally transferred image on a strip moving past the thermal head. The meter tape is cut prior to the strips moving past the thermal head.

Abstract: A postage meter which includes a thermal print head for printing indicia, postal value, and the like is disclosed. In accordance with the invention, thermal elements in the thermal print head are electronically pulsed in appropriate serially timed patters to provide a complete thermally transferred image on a strip moving past the thermal head. A reversible stepper motor and cam arrangement are utilized to provide a drive mechanism and a means for relieving pressure on the strip at the end of each print cycle.

Abstract: A paper transport device for a recorder such as an ink jet printer has a support for clean paper, guidance rollers, and a drive device. The transport devices moves the paper from the paper support past a printing head. In order to exert a symmetrical pull on the paper and simultaneously to make substantially the entire width of the paper available for writing thereon, the paper transport device has at least two rollers mounted on an axle rotated by the drive device, the rollers being disposed a distance from one another at right angles relative to the forward feed direction of the paper. The drive rollers are mounted on the axle so as to run freely on the axle in the direction of rotation of the axle, but lock when attempted to be rotated in the opposite direction so that skewed paper is easily and automatically aligned to move in a straight path. Each drive roller has an idler roller associated therewith.

Abstract: An easily adjustable and automatically aligning pinch roller assembly for use in a graphics plotter. A movable carriage hangs from a supplemental inverted T-shaped track below the main carriage track of the plotter. The pinch roller is pivotally attached to an arm from the carriage. A leaf spring on the carriage pulls the carriage loosely into positional alignment with the pinch roller aligned with the drum while allowing translational movement easily. A second bias spring urges the pinch roller down and the carriage into gripping engagement with the supplemental track with sufficient force to prevent translational movement thereof. A release bar holds the pinch roller off the drum and releases the gripping force to allow the carriage to be slid for adjustment.

Abstract: A compensation circuit is described for use in a line scan type recording apparatus where an electron beam is scanned on the face of a fiber optic cathode-ray tube (FOCRT) in synchronization with a movable recharging medium. The compensation circuit includes a charge pump circuit, an integrator circuit, and a current source. The charge pump circuit draws a constant charge from the integrator circuit in response to a repetitive series of stepper pulse corresponding to the velocity changes in the recording medium. The current source generates a constant current that flows into the integrator circuit and is equal to the average DC current flowing out of the integrator circuit via the charge pump circuit. The output voltage of the integrator circuit is used for controlling the vertical displacement of the electron beam of the FOCRT in synchronization with the movable recording medium.

Abstract: A recording paper feeding apparatus for use in a recording machine such as a facsimile machine includes a predetermined paper travelling path along which a recording head, a platen roller, a cutter and a paper discharging roller are disposed. In one form of the present invention, a first detector for detecting presence and absence of the recording paper is disposed upstream of the recording head and a second detector for detecting presence and absence of the recording paper is disposed downstream of the cutter. And, signal sound is produced when both of the detectors detect presence of the paper, indicating that the paper is properly loaded. In another form, a switch is provided and if at least one of the detectors is detecting absence of the paper when the switch is actuated, alarm sound is produced, indicating that the paper is not properly loaded.

Abstract: A recorder has a chart feed mechanism for automatically loading a chart for recording operation. By loading a chart stock storing a chart into a recorder case, discharge roller and feed roller of a chart feed means are actuated to feed the chart into a condition in which data can be recorded thereon.

Abstract: A pen recorder comprising a pen which is adapted to be placed in contact with a recording paper, a return spring which is capable of energizing a pen so that it is separated from the recording paper and a push-out means which pushes the pen so that it can be placed in contact with the recording paper. This push-out means includes a push-lever urging the pen towards the recording paper against a spring force larger than that of the return spring. During the printing operation, this push-lever is separated from the roller, while during the waiting condition, it engages the roller. Accordingly, stabilized pen feed rate and contact pressure of pen can be realized during printing operation.

Abstract: A sheet presser mechanism for use in a recorder comprises a platen rotatable about its own axis, a drawing instrument directed toward the platen and movable axially thereof, a pair of spaced support members movable toward and away from the platen, a pair of presser roller units rotatably supported on the support members, respectively, and positioned respectively at axial ends of the platen. The presser rollers have shafts parallel to the platen and normally held resiliently against the platen, and a paper presser bar is spaced from the presser rollers in a circumferential direction of the platen so as to extend parallel to the platen. A pivot lever with a cover thereon supports the paper presser bar for moving the latter away from the platen, and a pair of presser members are actuatable in response to turning movement of the pivot lever to move the paper presser bar away from the platen for pushing the support members to move the presser rollers away from the platen.

Abstract: Electronic equipment with a printer has a special graph print mode designation means, in which, when a special graph print mode is designated by the special graph print mode designation means in a graph data input operation, the print density of the corresponding graph data area in the graph is modified.

Abstract: Novel strip chart recorders and strip chart recording paper are provided which are cooperable so that the recorder detects the proximity of a terminal edge of the paper, so that the recorder can signal this occurrence to the user enabling him to insert a new supply of strip chart paper in the recorder to avoid the loss of data. The recorder also cooperates with the strip chart paper to determine when paper is absent from the recorder, for example, when it has been exhausted, thereupon to signal this further occurrence to the user and take steps to avoid damage to the recorder which can result through its operation in the absence of paper in the recorder mechanism.

Abstract: A recording apparatus comprising a paper feed device for feeding a recording paper in forward and reverse directions; a carriage for supporting a writing tool and being movable perpendicularly to the feed direction of the paper; a carriage drive device for driving the carriage; a writing tool drive device for driving the writing tool towards the recording paper; a character pattern generator for generating character patterns; a control device for reading out corresponding character pattern data on basis of record data and driving the carriage drive device and the writing tool drive device to control the paper feed device, in response to the character pattern data; change means for changing lateral and longitudinal directions of recording; and means for mutually changing drive signals to be supplied from the control device to the paper feed device and the carriage drive device, respectively, on the basis of the change means, whereby direction of recording can be simply and readily changed.

Abstract: An electronic apparatus has a ball-point pen as the recording means and rotatably supports a roll of printing paper on a shaft provided on the side surface of the main body of the electronic apparatus, wherein the shaft to support the printing paper is made hollow inside, a cap is fitted in each opening at both ends of the shaft in a freely openable and closable manner so as to enable spare ball-point pens and a ball-point pen removed from a carriage of the electronic apparatus, when it is not in use, to be housed inside it.

Abstract: A sheet pressing mechanism in a pen type recording device including a rotatable platen and a pen adapted to move in the axial direction of the platen while contacting the platen, in which pressure rollers are brought into contact with outer peripheral surfaces of end portions of the platen, the pressure rollers being rotatably mounted on a support shaft extending in parallel with the axis of the platen, and in which the said outer peripheral surfaces of the end portions of the platen are formed of a soft material capable of being depressed by the contact pressure of the pressure rollers.

Abstract: Apparatus for assisting in the loading of strip roll paper in a graphics drum plotter having a vacuum column disposed between a strip paper supply roller and a drum wherein insufficient space is available between the drum and the beam/writing head above it for reaching through to grasp the paper on the supply roller for pulling it through. A hook-shaped wire guide is hingedly attached through a slot in the center of the back wall of the vacuum column. The guide wire is biased by a counter weight to a position within the vacuum column and is moved out of the vacuum column through the slot from the force of paper descending into the vacuum column. The hook is shaped to guide paper being rolled off the supply roller across the space between the front and back walls of the vacuum column and to direct it into a position between the drum and the beam/writing head where it can be grasped.

Abstract: An electronic apparatus includes a printer for graph printing, in which the vertical and horizontal dimensions of the printed graph can be modified by a device for modifying the scales of the graph.

Abstract: A sheet guide mechanism in a recording device including a rotatable platen and a recording member opposed to the platen, comprising pressure rollers adapted to come into pressure contact with the platen for pressing down a recording sheet, and a guide plate extending from a lower portion of a recording side of the platen in a direction opposite to the recording side past below the platen, the guide plate having windows formed therein for avoiding the pressure rollers and guide pieces formed on edges in a sheet inserting direction of the windows, the guide pieces being bent in a direction away from the platen.

Abstract: A convertible platen for use in a graphics plotter to allow its selective use as either a cut paper plotter or a roll paper plotter. The platen is formed from a specially designed aluminum extrusion and a pair is mounted with one on either side of the drum of a drum plotter between the drum and the supply/takeup rollers. The platens can be raised and held adjacent the drum and spanning the vacuum columns in the plotter to create a table having curved outer edges to support cut paper. They can be released and dropped into the vacuum columns whereby they lie against the outer surfaces and form the upper inner wall with curved upper edges over which paper smoothly is guided between the vacuum columns and the supply/takeup rollers.

Abstract: In a plotter, an elongated strip of plotting paper extends between rolls at opposite ends of a plotting table to receive graphic information from a plotting instrument that is carried over the table by means of a motor controlled carriage. Different segments of the elongated strip are shifted onto the work surface of the table to receive the graphic information by coupling the strip to the plotting carriage and moving the carriage together with the strip across the table in an indexing operation. To prevent distortion of the material and associated positioning errors during the step of indexing, the material being pulled onto the table by the carriage is placed in tension and the material being discharged from the table is maintained substantially tension-free.

Abstract: A recording apparatus in which recording is made several times each line in a partitioning manner part after part on each recording line for which there exists picture data to be printed. The system determines whether there exists picture data to be printed on each line or not. A sub-scanning speed per line is set such that when the determination is made that one or more successive lines immediately before a recording line for which there exists picture data to be printed is or are an entire blank line or successive entire blank lines for which there exists no picture data to be printed, the sub-scanning speed for the entire blank line or successive ones of the successive entire blank lines adjacent to the recording line is selected to be substantially equal to that at the recording line. The sub-scanning speed of other entire blank line or lines for which there exists no picture data is selected to be a speed which is sufficiently higher than that for the recording line.

Abstract: In a thermal transfer type recording apparatus, a sheet separation system includes a separator member positioned downstream of a thermal head with respect to a predetermined path which a recording sheet and an ink sheet move in contact with each other. The separator member is selectively controlled to move between an inoperative position above the sheet path and an operative position below the inoperative position and which interferes with the sheet path. In the operative position, the separator member pierces the ink sheet downwardly to push the underlying recording sheet away from the ink sheet.

Abstract: A heat sensitive recording apparatus using an ink donor sheet in the form of a continuous band includes a device for detecting and correcting the tension applied to the band so as to prevent creases, etc. from being formed therein.

Abstract: A printer such as an ink jet printer in which a record carrier is fed around a transport roller and over an elongated flat supporting surface extending alongside the roller, with a printing head displaceable along that surface. To cause the carrier to lie flat under the printing head, the surface lies in a plane which is a secant plane with respect to the roller, the secant defining a roller circular segment having a height less than half the roller radius. Between the head and the roller, a ruler presses the record carrier toward but not against the flat surface at that location, causing the carrier to lie flat under the printing head.

Abstract: A cassette for a scratch strain recorder has a rotatable supply bobbin geared directly to a rotatable take-up bobbin so that rotation of the take-up bobbin will be equal in amount but opposite in direction to that of the supply bobbin. The recording tape is formed of a roll of flat resilient material which has one end attached to the supply bobbin and which, in the unused condition, is almost totally wound around the supply bobbin except for the other end which is attached to the take-up bobbin. The tape is driven by a capstan and pinch roller, the capstan being arranged for driving connection to a drive shaft of the strain recorder itself. Because of its inherent resilience the coil tries to straighten, i.e. unwind, and this assists rotation of the two bobbins when the capstan is operated and the direct gear interconnection causes an equalization of the spring forces between the two bobbins as the cassette progresses from an unused condition to a nearly completely used condition.

Abstract: A graphic recorder of the vacuum column buffer type has a pair of wells into which the two loops on the sheet material are drawn down. Top and bottom sensors are provided in each well for maintaining the loops within a predetermined range of movement; but in addition, the supply and take-up rolls are slaved to the speed of the drum. Cross-coupling is provided between the two wells to tend to equalize the vacuums therein.

Abstract: A printing apparatus wherein a transfer printing medium brought from the feed reel by the pinched transfer printing medium-forwarding mechanism is superposed on one unimpressed sheet after another supplied from a sheet-feeding means; data is impressed on the printing plane of the sheet; the pinching of the transfer printing medium by said transfer printing medium-forwarding mechanism is effected by means of a link mechanism interlockingly with the superposition of the printing head block on the transfer printing medium, and the disengagement of the transfer printing medium from said transfer printing medium-forwarding mechanism is effected also by means of said link mechanism interlockingly with the release of the printing head block from the transfer printing medium; and the above-mentioned pinching and disengagement of the transfer printing medium are respectively carried out by a single operation, thereby simplifying the loading of said transfer printing medium on the subject printing apparatus.

Abstract: A single stepper motor is utilized in a printing device to lift a print head from the surface of recording material upon the initial angular rotation of the stepper motor output drive shaft and to move the recording material within the printing device upon further rotation of said drive shaft. The print head is returned to the surface of the recording material by operating the stepper motor in the reverse direction until the output drive shaft of the stepper motor traverses an angular displacement equal but opposite to the initial angular displacement. A cam surface couples the output drive shaft of the stepper motor to a drive gear and transforms the initial angular displacement of the output drive shaft into linear motion to lift the print head from the surface of the recording material. Further rotation of the stepper motor drive shaft rotates the drive gear to move material within the printing device.

Abstract: A system for recording graphic information, stored in digital form in a data memory, on a moving record medium comprises a controller which is responsive to the travel rate of the moving record medium to supply digital signals from the data memory to a recording member in synchronization with the movement of the record medium.

Abstract: Disclosed is a pen type printing apparatus having a reduced size and weight suitable for use in combination with a personal computer or the like. The apparatus has a paper feed roller adapted to be driven by a motor. Two short roller shafts are arranged at each axial end of the paper feed roller so as to extend in parallel with the latter. These roller shafts rotatably carry respective pressing rollers of small diameters. The roller shafts are biased toward the paper feed roller to bring the pressing rollers into pressure contact with both axial end portions of the paper feed roller to clamp a printing paper therebetween. A carriage is movable transversely of the printing paper and carries a pen which is projectable selectively. Any desired character, symbol or a chart can be printed on the substantially mid-portion of the printing paper where no pressing roller exists, by a combination of the shifting of the carriage, feed of the paper and the projection of the pen, in accordance with a printing instruction.

Abstract: An improvement to a chart recorder where the chart paper is driven by a motor responsive to pulses counted by a microprocessor makes it possible for the operator to return the pen at any time to the starting point of the last chart scan by merely pressing a key. Using a programmed counter the microprocessor keeps track constantly of the number of counts since the start of the scan. On key command the microprocessor directs the motor to return through this number of counts plus 50; then to go forward 50 counts thus taking up any backlash in the chart drive so as to return exactly to the initial point of the scan. The subroutine also raises the pen during return and lowers it at the starting point.

Abstract: An improvement to a chart recorder where the chart paper is driven by a motor responsive to pulses counted by a microprocessor makes it possible for the operator to set the pen to a major grid line on the chart at any time after initialization by merely pressing a key. Using a programmed counter the microprocessor keeps track constantly of how many counts the paper has advanced and how far it is to the next major grid line. Upon key command the microprocessor through a software routine advances the paper to the next major grid line. If desired, the routine can also be programmed to raise the pen during advance and lower it at the major grid line.

Abstract: A chart recorder useful in a marine depth sounder or in other applications. Chart paper for the recorder is loaded into a paper cartridge, which is insertable in the recorder. The paper cartridge supports a roll of chart paper, a takeup spindle for winding the paper, and a viewing surface across which the paper travels after data marks are recorded on the paper. An internally-driven roller within the recorder frictionally engages the takeup spindle when the cartridge is in place, so as to move the chart paper at a selected linear speed. The drive roll is operated by an electric motor and a multiple-stage compound reduction gear arrangement, all entirely contained within the drive roller.The paper marking stylus of the recorder makes full-time contact with a stylus engaging surface throughout each revolution of the stylus drive belt. An inductive sensing device is located between sides of the drive belt, and senses a magnet carried on the outside of the belt.

Abstract: Apparatus for printing alpha-numeric characters for plotting an incoming signal at rates on the order of one page every seven seconds for rapidly verifying that the system producing the incoming signal is operating properly. Both printing and plotting are done by styli mounted on a moving carriage and individually electrified to produce marks on a specially prepared paper. The styli are moved back and forth across the paper, marking in both directions. The carriage is not stepped across the page, but instead is moved smoothly from one side to the other side under control of a velocity servo. A controller generates and applies velocity command inputs to the servo, based on the position of the carriage as sensed by an optical encoder, and based on certain characteristics of the incoming signal. A first buffer memory accumulates the incoming signal until a line has been stored for plotting, while a second buffer memory is applying its accumulated contents to the printhead.

Abstract: Apparatus and Method for providing images on a photosensitive media is disclosed. The invention provides for the multi-point exposure correction of recorded grey scale hardcopy images which utilizes line by line attenuation of video data in a unique pattern. Also exposure compensation is provided for by decreasing the amplitude of the video signal, on a line by line basis, from a predetermined nominal value which is in the recording cathode ray tube's dynamic range. The invention thus performs its function without compromising the dynamic range of the recording mechanism.

Abstract: A plotting system (10) including a plotting device (40) for plotting on paper (52) is provided. The plotting system (10) includes a work surface (28). A supply source (50) of paper (52) to be plotted is disposed adjacent the work surface (28). A take-up roll (56) is disposed adjacent the work surface (28) opposite the supply source (50). A supply source (64) of carbon paper (66) is disposed adjacent to the work surface (28). A take-up roll (72) is disposed adjacent the work surface (28) opposite the supply source (64). Structure (60) is interconnected to the first take-up roll (56) for periodically advancing the paper (52) across the work surface (28) from the supply source (50) to the take-up roll (56). Structure is interconnected to the second take-up roll (72) for continuously advancing the carbon paper (66) across the work surface (28) from the supply source ( 64) to the second take-up roll (72) while the plotting device (40) plots on the paper (52).

Abstract: The present invention is directed to a recording apparatus comprising feeding and receiving means for recording paper that are positioned under a recording surface and rollers, whereby either the feeding means and/or the receiving means can be removed from or installed through the top of the recording apparatus for changing the recording paper.

Abstract: A chart recorder has all of its components mounted in a housing formed of a self-lubricating plastic material. The unit employs a single drive roller which is driven through a speed-reducing gear train by a low-torque motor and belt drive, which produces minimal noise. A special tilt plate is mounted behind the drive roller. The recorder has a swing-down front door which is movable between an open paper-roll-loading position, an intermediate paper-feed position and a closed operating position. When the door is in its paper-feed position, paper drawn from the roll can be fed manually between the roller and the tilt plate so that the recorder can be threaded up without power. When the door is closed, it resiliently biases the tilt plate against the paper trained around the drive roller so that, when the drive train is energized, the paper is advanced promptly and smoothly. A simple wire bail and cam surface locks the door in its intermediate and closed positions while simultaneously raising the recorder stylus.

Abstract: Apparatus for controlling the stepping of a pen and chart of a recorder is described in which the data is buffered so as to free up the processor. The pen steps as fast as it can and no new data points are read until the pen-stepping data is used up. The chart stepping is keyed to the reading of data points so that while the pen is moving to a desired position, the chart stands still.

Abstract: Electrocardiographic apparatus including a novel and improved recording paper feed and lead switching arrangement which include a platen having a platen roller, both movable from an open position for installing a supply of recording paper to a position wherein the platen roller with recording paper fed about the surface thereof is moved to an operating position with the platen roller in recording engagement with a recording pen. A paper drive roller is positioned in adjoining relationship to the platen roller and engages the platen roller with the paper thereon when in the operating position. The recording paper is provided with spaced cue marks and transverse perforations between successive cue marks and the apparatus includes a cue detector and associated electric circuitry for detecting said cues so that heart muscle signals from successive groups of patient leads will be recorded on successive segments of the paper defined by the perforations.

Abstract: A paper transport simulates movement of a plurality of documents past the print station of a ink jet printer. The transport includes an arrangement for transporting a continuous paper web past the print station and a tachometer drive roller for contacting the tachometer wheel of the printer system. The transport further includes a document simulator wheel aligned with the photo-optical document detector of the printer system such that the movement of a succession of documents past the print station may be simulated while the printer system prints upon the continuous paper web.

Abstract: A moving-medium XY plotter is provided with a platen which has a concave surface extending uniformly in the direction of pen motion. A drive roller and pinch roller assembly located near the bottom of the concavity provides the motion of the recording medium orthogonal to the pen motion, while at the same time curving the recording medium into the shape of a trough. This curvature stabilizes the motion of the recording medium by significantly enhancing its resistance to compressional buckling and ensures that the recording medium, as a result of its natural stiffness, will firmly contact the platen where writing is to occur.

Abstract: This disclosure is concerned with a novel digital multi-point recorder that is microprocessor-controlled and enables impact printing from in back of the recorder paper to provide a front visible flat print-out of pages of on-line running summary data suited for operator viewing in industrial and similar locations, and providing a record for direct use in reports and logs.

Abstract: In an exemplary embodiment, the recording paper is transported by at least one drive capstan driven by a motor across a writing surface at which a fluid writer is disposed for writing. The object of the disclosure is to create a paper transport system which always avoids unnecessary contaminations due to writing fluid with certainty. This object is achieved in that the motor-driven drive capstan has a no-load indicator allocated to it which identifies no-load operation of the drive capstan and generates a shut-down signal for the fluid jet writer.

Abstract: The present invention is directed to a recorder having recorded paper mounted to advance from a body with a curved surface to a roller lengthwise, and with at least one recording stylus mounted to move transversally across the width of the recording paper as it moves lengthwise. Additionally, a lead piece is placed in the path of the recording stylus extending over the edge of the recording paper to smoothly lead the recording stylus into the recording paper. This lead piece is rotatably supported on the recorder, with a means for continuously biasing the lead piece in a direction to withdraw the lead piece from the path of the recording paper, along with an obstruction positioned to push the biasing means to retain the lead piece over said recording paper.

Abstract: A clutch arrangement for a spool mechanism. The arrangement comprises two clutches, namely an over-running clutch and a constant torque clutch whose respective driven members are connected to the spool bearing and whose driving members are capable of being connected to a drive means. The over-running clutch transmits to the bearing a torque which is substantially greater than the torque applied by the constant torque clutch.

Abstract: In a potentiometric chart recorder, the speed of the chart motor 22 is, in one mode of operation (AUTO) selected by a switch 32, varied between two values in dependence upon the rate of change or slope of the input signal at 10 as detected in a detector 30. The slow speed is obtained by intermittent operation at the fast speed, and during the non-operative periods power-consuming circuitry e.g. 16, 18, 26 is switched off by a switch 40.