JPS59131484A - Position indicator for high-speed printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the lateral position of a print head or other device relative to the surface of a sheet of paper or document, e.g. The present invention relates to a position indicator for determining the lateral direction of a dot matrix print head of a high speed printer for single sheets of paper having a dot matrix print head formed on the surface thereof (and the like).

For the sake of brevity, the position indicator (
Emphasis is placed on position indicators for determining the lateral position of the printhead associated with printers of the type disclosed in U.S. Pat. No. 4.15c+, 5s24. It is placed.

However, it should be noted that position indicators are also used in other types of printers and other types of devices.

In high-speed printers of the type disclosed in the aforementioned U.S. patents, characters are moved across the paper on which they are to be printed (e.g., parallel to the axis of the printer's platen) by a stepper motor via a cabling and cable system.
, the print head is moved.

A step motor does not only act as a drive mechanism.
Its position with respect to the periodic pulses also acts as a determinant of the lateral position of the print head relative to the paper. Stepper motors are relatively expensive, and they provide instantaneous mechanical power to the device, which must be properly controlled to obtain accurate position.

The commonly used method using optical sensors is
on the horizontal slew motor.

A sensor such as the HEDS5000 series optical sensor manufactured by Hewlett Paracard is provided.

For this reason, the motor shaft vibrates violently every time it rotates.
A disadvantage is that the quadrature detection circuit required to prevent recording loss is very complex. Additionally, there is considerable cable stretch during acceleration (2 to 10
mill).

Also, since this cable must be attached to the printhead carriage near the center of the body, the azimuth tolerance will limit the amount of error in where the printhead prints on the paper. lead.

Other equipment uses a Plinchik Model 920 printer. The device has a nine-way optical rotary encoder mounted on the printhead carriage. - This device introduces large errors in print position as a result of directional tolerances on the horizontal sideways slide bar.

The positioning action of the stepper motor can also be performed by an optical shielding device that utilizes light, but none of these devices provide sufficient resolution to obtain the required accuracy. Many problems common to optical fencing devices must be overcome.

Generally, optical fencing devices use a pattern of alternating highly opaque and highly transparent bars. The spacing between consecutive bars of the same type can be considered as a wavelength.

On the other hand, a bar pattern can be made reflective if the bars alternate between being highly absorbing and highly reflective.

Merely having an optical shield as described above is insufficient for use in determining position.

Ordinary light is scattered as it is transmitted or reflected through such obstructions. Therefore, in order to emit only the vertical component of light from the shielding object, the method described above must be used.

One way to do this is to use a very narrow slit (again relative to the pattern wavelength) close to the shield. However, as the pattern wavelength becomes smaller, the total amount of light (area intensity of light) becomes very small.
Moreover, the signal formed is very weak and therefore very difficult to detect.

Another method also uses a transparent shield that works in conjunction with a second transparent shield of the same geometric pattern.

The movement of the second shield relative to the first shield is such that the phase angle of the second pattern with respect to the first pattern is shifted.

When two transparent parts are aligned, half of the light source is transmitted through the transparent parts of both shields. When the transparent portion of the first shield is aligned with the transparent portion of the second shield, the transparent portion of the first shield is aligned with the transparent portion of the second shield. As a result of lining the parts, the light source is all blocked by an opaque area, thereby preventing light from hitting the detector.

The advantage of this type of shield is that the amount of light available to the detector is the sum of the light passing through several transparent bars when lined up as above; Therefore, the ratio of the light intensity to the dark area is much higher than in the case of a single slit.

Despite these advantages, devices with double shielding
As unsuccessful attempts were made to increase resolution, serious problems began to emerge.

In particular, as the pattern wavelength decreases to the point where the spacing between the fixed bar pattern and the movable bar pattern is a significant portion of the pattern wavelength, the scattering of light due to refraction increases the intensity of the light (as the pattern becomes opaque). When aligned, the amount of light shining onto the detector decreases, thereby reducing the ratio of bright to dark areas.

Physical changes and mechanical system variations cause amplitude modulation of the detected signal, making it difficult to discern its exact content.

Dust and dirt, grease and other contaminants increase light scattering and absorption, thereby reducing the light to dark ratio.

All these problems are difficult to solve with the resolution provided by conventional techniques. Although some of these problems can be overcome by careful design or by exact tolerance tolerances, their commercial availability is limited by cost and other considerations.

This method has the disadvantage that the ideal location for the optical sensor is the same as the print head. When an optical sensor is placed next to the printhead, the tolerances in the bearings associated with the horizontal lateral sliding bar create large errors in the position of the printhead on the paper it prints on. It turns out.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly accurate positioning mechanism for a printer which does not suffer from the above-mentioned disadvantages and which provides a much cheaper and more reliable mechanism.

A further object of the present invention is to provide a mechanism in which something other than a stepper motor (eg, a DC motor) can be used for use in moving the carriage.

According to the present invention, there is provided a device comprising a first and a second member configured to allow relative movement between the two members, and a drive device for causing the relative movement; a position indicating device for indicating the relative positions of the first and second members, the device comprising an optical position encoder device arranged to rotate with respect to the first member; The first member rotates the optical position encoder device in synchronization with the second member,
a position-responsive device separate from the drive device configured to transmit motion from the second member; It has a pattern of rounded detectable markings that provide an indication of rotational speed.

According to a preferred embodiment of the present invention, an elongated platen and a print carriage configured to effect a relative movement between said elongated platen in the longitudinal direction of the platen; , a drive device for driving the carriage, and an optical position encoder rotatably mounted on a shaft fixed in the longitudinal direction of the platen for ascertaining the position of the carriage in the longitudinal direction of the platen. a position pointing device connected to the carriage directly adjacent to the printhead and encoder for rotating the encoder in synchronization with the relative movement; a carriage position-responsive device for transmitting motion, separate from the carriage drive, the encoder having a pattern of detectable markings;
a detector responsive to said mark for providing a signal indicative of said position.

Preferably, the position-responsive device is a substantially non-stretchable cable connected to the carriage in close proximity to the print position of a print head disposed above the carriage, thereby ensuring that the print ( position and relative movement of the platen is faithfully transmitted.

The encoder is disc-shaped, and the marking pattern consists of thin stripes radial to the axis of the disc.
It is preferable that it consists of a bar). Desirably, the stripes are alternately transparent and opaque.

A light source shines light onto the pattern to provide a transmitted light pattern consisting of the intensity of multiple light regions (photon packets) separated by regions of substantially zero light intensity. It is.

In this case, the relative motion between the disk and the light source causes each region among the regions to
The light intensity substantially changes from O (that is, a dark state) to a moderate light intensity.

A lens is placed to focus light from the light source onto the pattern. Additionally, another lens is positioned to receive the transmitted light pattern and is utilized to collect the light pattern.

A crosshair is placed to receive the focused pattern from the disk. The crosshair consists of a short strip with a pattern of thin stripes oriented at right angles to the annular extension of the strip. These thin stripes are alternately transparent and opaque (either absorbing or reflective).

When the magnification of the lens system is 1, the spatial wavelength of the thin stripes of the crosshairs is the same as the wavelength of the disk.

As another example, it is also possible to use different magnifications in the lens system, in which case the wavelength of the crosshair pattern is such that the pattern of light falling on the crosshairs has the same wavelength as the wavelength of the crosshairs. It is calculated appropriately depending on the magnification of the lens.

Under these conditions, the action of the crosshair is such that light corresponding to the transmissive area of the crosshair is allowed to pass through it, and light corresponding to its reflective area is blocked.

When the light emitted from the disk is aligned with the transmission area of the crosshair, the maximum amount of light possible will pass through the crosshair. Furthermore, when lined up with the non-transmissive area of the crosshair, even the smallest amount of light passes through. A quarter wavelength detector is placed behind the crosshair to detect the total amount of light coming from the crosshair. The detector provides a signal that can be analyzed to indicate lateral position relative to the light source.

The focused light analyzed in this field consists of at least some light intensity regions (photon packets) that are combined and yet averaged in the detector to generate the signal. There is.

The output of the quarter wavelength detector is processed to provide a digital direction signal and a video signal indicating the lateral force direction of the carriage and the position of the carriage with respect to the platen.

The resulting signal is sent to a microprocessor containing a 16-bit register of printhead horizontal position. The microprocessor measures velocity (by measuring the number of video pulses the printhead receives during a pass) and acceleration by measuring the difference in successive velocities.

In one way, this can be accomplished with hardware. The microprocessor uses video pulses and generates firing pulses for the printhead without using a pin-fire buffer to compensate for the loss of time as the printhead passes.
Improved speed and acceleration to change non-load addresses.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figures 1 and 2 1 show a carriage drive (horizontal travel mechanism) according to the invention, in which a print head carriage (1) on which a dot matrix print head (2) is provided; is the horizontal support rod (31(4)
The carriage (1) is slidably supported on the rod (31 (4)) and is moved along the rod (31 (4)) by a drive belt (5) actuated by a direct current motor (6), thereby , the print head is attached to the platen (which allows for the necessary lateral movement with respect to force).

The dot matrix print head (2) has a printing pin (8) whose selective operation causes an image of the ribbon 00) to be printed on the paper (9). The carriage position sensitive cable aυ is attached to the carriage by two posts a located in close proximity to the pins in the print head α.

This ensures the transmission of the print position movement relative to the paper (9) regardless of tolerances and wear in the carriage bearings on the support rond.

The character position response cable is attached to an idler pulley 1.1-(131) rotatably mounted on the printer chassis at one end of the carriage along the platen (7).
Extending from the periphery of the printhead to an optical disk encoder rotatably mounted at the other lateral end of the print carriage along the platen.

The optical disc (14) carries a plurality of indicia in equally spaced radial opaque lines with the spaces between the lines being opaque.

The belts and cables used herein may be replaceable, and flexible drive members such as chains or other link members may be substituted for the belts or cables without departing from the scope of the invention. It can be used for

Since the carriage position reaction cable 01) is designed to drive only the idler boob V-43I and the optical disk encoder Q41, there is almost no inertial force, and the cable generates a pulling force on itself. You can use something that is extremely lightweight.

As a result, the optical disk encoder can reliably measure the horizontal (lateral) position of the printhead with respect to the platen and the paper supported on the platen.

In this preferred embodiment, the idler pulley α and the optical disc encoder α are rotatably mounted on a relatively rigid platen structure protrusion (I), and the protrusion (t!9 is It is mechanically isolated from the structural support and the drive DC motor (Ie) by a vibration isolator (Ie).

In FIGS. 3 and 4, the optical disc encoder α is a pulley with a peripheral groove that can be engaged with the cable 01). The pulley is made of transparent plastic and equally spaced radial transparent lines [Iη (light shielding), line a
η is sandwiched in the center of the pulley.

The pulley has a shaft (1
19.

The photodetector and transmission device ■ are light emitting diodes (LEDs)
It includes a light transmitting device (2I) having the shape of , and a lens (c) for focusing the light emitted by the LED onto the radial #αη.

Lens C! :(l di The space between multiple radial gauze αη receives the light from the LED and transforms it into a quarter-phase crosshair (
24) Focus on the crosshair (241), block the received light with the quarter-phase detector Q at the top, and
2ω generates a target output signal which can indicate the lateral position of the Rad Carriage (1) to the print with respect to the received light and platen (7) K.

The radial g tl forces are desirably evenly spaced throughout the tubular portion of the optical disk encoder where the ribs are shown, although only a portion of the radial force is shown in FIG.

In order to keep the level of the signal from the detector constant, it is important that the light source uniformly illuminates a portion of the disk. This is achieved by ensuring a relative mechanical relationship between the light source and the light sensor, placing each other in close proximity to the surface of the disk.

The crosshairs located in the image plane are separated by transparent areas separated by opaque areas corresponding both in size (width) and position relative to the area of light and the area of the transmitted light pattern, i.e. It has a pattern of stripes (e.g. slots).

The pattern of light is transmitted through the crosshairs when the area of light coincides with a transparent area, and blocked when the area of light coincides with an opaque area.

A quarter-phase detector (c) receives all the light transmitted through the crosshairs and converts the light energy into an electrical current that can indicate the lateral position of the printhead with respect to the platen.

The analyzed light is composed of at least several light regions of intensity and is focused or dispersed within a detector to generate a voltage signal. The detectors in the sensor are a pair of detectors.

The crosshairs are divided crosshairs with regions that are 90° divisions of space from each other, each capable of sensing (with respect to the spacing of the crosshair stripes) light of 0-phase and light of 902 phase. It looks like this.

The regions are spatially quarter-phase with each other, and some regions of the tsumami-cross net are each quarter-phase of the other regions.
The widths are transposed or offset to the right of each, and the ribbing allows for maximum light to be produced in different locations from where other areas are gathering maximum light.

The 0-phase light is sensed by one detector (e.g., a photosensitive diode) and gives a voltage signal that is connected as an input to an amplifier whose output is connected as an input to a comparator. be done.

The 90°-phase light is sensed by a detector and its output is amplified and connected to a comparator.

The crosshairs are placed in close proximity to (eg parallel to) the detector. The crosshairs are placed on the surface of the Shima detector, and when the crosshairs are close to the detector, the scattering of light to the detector is greatly reduced, and even if the wavelength of the pattern is very short, most of the light is It is noteworthy that the signal from the detector is reduced.

Having a split crosshair with two crosshairs, the canceling effects from each other in the direction of movement of the disc with respect to the light source sensor make the circuit shown in Figure 5 reliable in the direction of travel, and this The direction of can be distinguished from the direction of -.

The offset of the crosshair portion typically has a quarter line width, ie makes an angle of 90°.

The two crosshairs forming the split crosshair are therefore separated in direction (eg, in the direction of travel) and occupy discontinuous positions.

Each output of the comparator is a digital signal d1 and 〆2.

FIG. 5 is a logic circuit showing the direction and video signals from phantoms 1 and h, which are sent to the circuit at inputs designated phantoms 1 and d2. Other inputs are fed by resistors R, R, R, and R4 at 5 volts and the system clock pulse (SYS CLOCK). The components, inputs and outputs of the components are as follows.

U, , U,', U, , U, and U, (74
LS74) is a standard LS TTL anode-triggered b flip-flop.

The AND gates of U, (74LS21) and Us (74LSO8) form an AND gate.

U, (74LS QO') is a Nantes gate.

U, , (74LS32) is an OR gate.

U, (74LS 14 ) is a standard inverter with hysteresis characteristics.

CLR is a "clear" input.

CK is the "clock" input.

D is the "data" input.

pH, is a "preset" input.

Q is "output".

Q is a "complementary output".

The input and connection of these parts are as shown in FIG. Detailed descriptions of these and the operation of the circuits are omitted as they are believed to be obvious to those skilled in the art.

The circuit provides a directional signal indicating the direction of carriage movement along the platen and, when the carriage movement is steady,
It produces a video signal consisting of a series of pulses corresponding to the leading and trailing edges of the digital signal σ2.

Thus, in steady state, each signal generated by the quarter-phase detector produces a single digital signal wave represented by two pulses at the video output.

However, a change occurs in the direction of the carriage's travel, and the end 2 has a leading edge and a trailing edge with no leading edge or trailing edge name that occurs in the temporal interval with the leading edge; The circuit U, typically generates a second pulse (Q) associated with each signal in the video signal.
, which is associated with the trailing edge of

At the same time, the state of the direction signal becomes uniform to affect the change in direction of movement. Ignoring the second pulse in the change of direction in the case described above is a major feature for blocking high frequencies. The cutoff is performed.
Otherwise, a servomechanism with little torsional resonance will cause errors in counting and moving operations when crossing at zero speed and slowing normal acceleration conditions.

The direction and video circuit outputs are input to the microprocessor. The output of the quarter-phase detector (video signal) is input to the microprocessor and 1. This microprocessor maintains a 16-bit register for the print head leveler. The microprocessor measures the speed (by counting the number of video pulses received during the printhead's flight) and still makes two consecutive speed measurements.

The acceleration is measured by measuring the difference between the

This operation can also be selectively performed by software.

The microprocessor uses the unloaded video signal from the pin line buffer to generate a filing pulse for the printhead and uses the speed and acceleration of the unloaded address to change the unloaded address to compensate for the time of flight. When the hardwired path producing the video signal is as described above and shown, a microprocessor may be utilized to perform similar functions.1 In an apparatus where an optical disk is reflected between the lines Preferably, the light transmitting device and the photodetector are placed close to each other on the same side of the disk, with the detector being placed to receive light reflected by the area between the two sides.

Furthermore, as will be clear to the person skilled in the art, - without departing from the inventive concept, the pattern of optically detectable labels can be modified to include non-optical label patterns (e.g. , magnetic ones, capacitance changes, structural ones, distortion-based ones, etc.).

Furthermore, the disks, pulleys may also be replaced by drums or other rotatable sign carrying devices, etc., carrying the signs around their periphery, without departing from the concept of the present invention.

[Brief explanation of drawings]

FIG. 1 is a plan view of a carriage drive device of a printer according to the present invention. FIG. 2 is a plan view of the carriage drive device shown in the first diagram. FIG. 3 is a partially enlarged view of an optical disc encoder according to the present invention. FIG. 4 is a partial cross-sectional view of the optical sensor of the optical disk encoder shown in FIG. FIG. 5 is a block diagram of a logic circuit responsive to electrical output from a light sensor. (+1 Printing Rad Carriage (2) Dot Matrix Print Head (31 (410 dots) (5) Drive Belt (6)
Curved flow motor (7) Platen (8) Rad pin to print (9) Paper 001! J-bond ([υ position reaction cable α2) pillar 03) Idler pulley a
(B) Optical disk encoder aω protrusion (16+ vibration isolator AL line Q81 axis 0 ■ bearing (2 ■ detection and transmission device Qυ light transmission device (c) lens
041 Cross Kizuna (25) Detector Patent Applicant Agent Patent Attorney So Takezawa -t,',6
f□j',":Mr. +"1 Inserting procedural amendment) February 23, 1980 Patent Office Director-General Kazuo Wakasugi 1 Indication of the case 1981 Patent Application No. 201873 2, Invention Name: High-speed Printer Position Indicator 3, Relation to the case of the person making the amendment Patent applicant〒；lung5゛”hair≠・・rde、・No Sanders, nooa t(伎－１石〉5) Amendment order Daily Newsletter January 1, 1982
1st (Delivery date: January 61, 1982) 8. Contents of the amendment Clarifying the engraving of the damage (no change in content)

Claims (9)

[Claims] (1) A device consisting of first and second members suitable for relative movement between them, a drive device that causes the relative movement, and a position indicator that indicates the relative position of the first member and the second member. A position indicator in which an optical position encoder [+41 and] is provided so as to be rotatable with respect to the first member. a position-responsive device α1) which is spaced apart from the drive device and which transmits movement from the second member to an optical position encoder and rotates in synchronization therewith; a detectable mark that the encoder has; a speed of rotation of the encoder; A detector Qυ031 (
2→(A position indicator characterized by consisting of two. (2) A print carriage for relative movement between the extension platen and the platen in the longitudinal direction of the platen, a device for driving the carriage, and a position for confirming the position of the carriage in the longitudinal direction of the platen. A position indicator in a printer consisting of an indicator, which is an optical position encoder a (I ) is connected to the carriage near the printhead and the encoder and transmits relative movement to the encoder to rotate the encoder in synchronization with the relative movement, and a carriage position response remote from the carriage drive arrangement. a device aυ and a detector glue (2
A position indicator characterized by consisting of (23I C!41 C1■). (3) In the printer, the mark carried by the position encoder is optically detectable.
The position indicator described in item 2). (4) In a printer, the encoder is a transparent disk and carries radially equally spaced opaque lines arranged in an annular play about the axis of rotation of the disk. The position indicator described in paragraph (3). (5) In a printer, one print head is a dot matrix print head having a plurality of print wires with the printing position at the end. The carriage position sensitive device is a flexible elongated member connected to opposite ends of the carriage, proximate the printing position, and rotatably mounted proximate one of the opposite ends of the elongated platen. Claim 2, characterized in that the carriage extends from the carriage to the encoder and back to the carriage and ridge by means of an idler wheel, the encoder being provided at the other end of the platen. position indicator. (6) In a printer, the elongated member is a cable, and the idler wheel and encoder are each a pulley having a groove that can be engaged with the cable and around the groove so that the cable rotates without slipping. A position indicator according to claim (5), characterized in that: (7) In a printer, the detector includes a light source arranged to transmit light straight through the space between the annular arrays, a signal that receives the light, responds to the movement of the array, and can indicate the position. The position indicator according to claim (4), characterized in that it comprises a photodetector that generates. (8) In a printer, the light source is a light emitting diode, the photodetector is a quarter-phase detector, and the light is focused by a lens onto a non-continuous region of the array, A phase photodetector is configured to receive light that has passed through an array and a lens that focuses the transmitted light onto the crosshairs by optically aligned quarter-phase crosshairs. A position indicator according to claim (7), characterized in that: (9) In the printer, claim (8) characterized in that the crosshair and the photodetector are provided close to the encoder disk.
Position indicator as described in section.