JPS5986962A - Recorder - 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 a printing apparatus, particularly a line scanning type printing apparatus.

Generally, in a line scanning type recording device, while the recording beam is repeatedly scanned over the recording paper in a direction perpendicular to its movement,
The recording paper is moved in one direction at a constant speed, and the intensity of the recording beam is modulated by an input signal, thereby forming a grayscale (halftone) image on the recording paper.

An example of a conventional recording device is a photosensitive paper and a fiber optic tube as the recording paper and recording beam, respectively.
1" OT) electron beam is used. In line scanning type recording devices, the speed of the recording paper is maintained constant,
Obtaining high quality recorded images is important. Although it is generally possible to move the recording paper at a constant average speed, it is very difficult to avoid short-term changes in paper speed, that is, errors due to the mechanical characteristics of the paper transport mechanism. As the paper moves faster, the linear density decreases and the image becomes brighter, and vice versa. Such a short-term paper speed change appears as a bright and dark striped pattern on the recorded image.

One solution to this problem is U.S. Pat. No. 4,172,259.
Disclosed in the issue. FIG. 951 is a block diagram of a conventional line scan recorder having the compensation means shown in this patent. The photosensitive paper (6) pulled out from the paper drum αe is moved at a constant average speed across the FOT (face brake of 21) 04)'.
It is driven by a paper drive means (4), for example a DC motor, via a drive roller (8).

The X-axis and Z-axis circuits each scan an electron beam along the faceplate 0 and modulate its intensity depending on the input signal. After a half-tone latent image is formed on the photosensitive paper (6) in this manner, it is heated and developed by a heating means (not shown). The speed detection means (c) has a light emitting means, a light receiving detector, and a light-shielding disc (not shown), and this light-shielding disc is connected to the drive roller (8) and has, for example, 360 slots along its periphery. It has an opening. Still, the velocity detection means (4) generate a pulse train, the frequency of which is proportional to the angular velocity of the shading disc. Also, the angular velocity of the light-shielding disk is proportional to the paper speed. Therefore, the frequency of the pulse train represents the paper speed. The compensation means (c) has a frequency-voltage converter, a long time constant differentiator C33, and an integrator (341).The frequency-voltage converter and the differentiator C33 generate a voltage signal proportional to the paper speed error. , an integrator converts the signal into a signal representing the time integral of each such error.

The integrator (3 outputs are applied to the Y-axis deflection circuit) to control the vertical movement of the electron beam scanning line and maintain a constant relative velocity between the electron beam scanning line and the recording medium. I'll do it like that.

However, in the case of such a conventional device, a disadvantage arises when the compensating means becomes complicated. Furthermore, the use of differentiators makes them unsuitable for recording devices having a wide range of controllable paper speeds.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a line scanning type recording device which is simple in construction and has improved compensation means to compensate for paper speed errors. It is an object of the present invention to provide a recording device with suitable compensation means for controllable paper speed.

FIG. 2 is a block diagram for explaining the principle of the improved compensation means of the recording apparatus according to the present invention. In summary, this improved compensation means uses a charge pump circuit (
4. It has a current source (42) and an integrator (4 (a).

The charge pump circuit (40) extracts a certain amount of charge from the integrator (4) every time the stepper pulse (to) corresponding to the pulse from the speed detection means (e) is received. A constant current IO is generated, and this current IO flows into the integrator (441).The constant current IO is selected to be equivalent to the DC average current flowing out from the integrator +441 via the charge pump circuit (4α). It will be done.

In other words, the constant current o is determined to supply a charge equal to the charge extracted from the integrator (44) by the charge pump circuit (40) during the average stepper pulse. vo is used to control the vertical or Y-axis deflection circuit (20).When the paper speed is faster than the average speed, the stepper pulses (38) become faster (closer spaced) and the output vo becomes more positive. On the other hand, when the paper speed is slower than the average speed, the stepper pulses become lower (more spaced apart) and the output Vo becomes negative.In this way, the output Vo is generated in response to the paper speed error. Ru.

FIG. 3 shows a block diagram of an improved compensating means for a recording device according to the present invention.

In addition to the compensation means shown in FIG. 2, the compensation means for the The DC stabilizing circuit connected between the terminals is an integrator (4
4) is provided to stabilize the DC level of the output vo. This DC stabilizing circuit (48) functions as a variable resistor, and its resistance value is controlled according to the paper speed voltage vsp. DC stabilization circuit (48
The + time constant is sufficiently long compared to the AC correction voltage, that is, the output Vo of the integrator (44), and is therefore not affected by this correction voltage. In some fixed paper speed applications, the DC stabilizing circuit (48) may simply be a resistor connected between the inverting input and output terminals of the integrator (44).

The S/H circuit (1161 is the output Vtl of the integrator (441)
This is provided to eliminate sweep and playback noise contained in the filter. This S/H circuit (461) makes the output vo constant at a predetermined time and is held during each step-halt period.

FIG. 4 shows an embodiment of the improved compensation means of a recording device according to the invention. The same reference numerals are used for the same components as those shown in FIGS. 2 and 3. Next, the operation of the circuit in FIG. 4 will be explained with reference to the signal waveforms in FIG. 5. . When a pulse (49) as shown in FIG. 5A from the l/-1i speed detection means (A) (FIG. 1) is supplied to the base of the transistor 5. The stepper pulse side as shown in FIG. 5B is obtained. This stepper pulse is supplied to both the charge pump circuit (40) and the 8/H circuit (46). The charge pump circuit (4α consists of a capacitor (52) and a pair of diodes 5a and (56); the integrator (441 is an operational amplifier (to) having an inverting input terminal, a non-inverting input terminal, and an output terminal); It consists of a capacitor (60) connected between the input terminal and the output terminal, and the non-inverting input terminal is grounded.The charge pump circuit has a connection point (43) of the current source (42 and integrator f44).
) is the virtual ground point in this example, so the current source (
4. The resistor can simply be a resistor. The voltage Vsp applied to the current source (42) is switched according to two or more different paper speeds selected by the operator. The current source 0 from the current source (421) is therefore also switched according to its selected paper speed.
(manufactured by RCA) f, used operational amplifier (has a surface and a transistor (circle).Paper speed voltage sp is a transistor (
6a, it is converted into a current and supplied to the amplification bias input of the operational amplifier (62). Therefore, the operational amplifier (6
21 works as a variable resistor, and its resistance value is the voltage ■sp
controlled accordingly. The DC stabilizing circuit (481) has a very long time constant, which is appropriately controlled depending on the paper speed, and the correction signal output to the output terminal of the integrator (44) is not influenced in any way by this circuit. It never happens.

The current source (4) is the integrator (even if the average DC current flowing out from the integrator is not completely balanced
The stability of the DC level of the output ■o of 41) is maintained by the DC stabilizing circuit (481. That is, the stability of the DC level of the output ■o
If is not accurate enough, the output o will either go in the positive direction or in the negative direction, depending on whether a little additional current has to be supplied or taken out. Drifted. In this way, the DC level of the output Vo moves up and down to compensate for its DC stability and settles at a certain DC level depending on the accuracy of the current generator O. If the current ■o is completely accurate, the DC level of the output ■o will be O. S/H circuit (the spine is condenser v-v3
), a resistor (6 marks and a sample/holt (S/H) element ff0), and an integrator (441 output vo sweep and reproduction noise are completely removed. A capacitor and a resistor (6EO
generates a sampling pulse as shown in Figure 5,
The S/H element side may be any conventional one. S/H element (
The output vo of the integrator (44) applied to the input terminal IN of the
When supplied to K, the instantaneous value of K is held, and this held voltage appears at the output terminal OUT as an output vc as shown in FIG. 5E. Output Vc of S/H circuit (4G)
Note that there is essentially only a level change remaining. This output vc is the Y-axis deflection circuit (
A) is used to control the vertical position of the scan line on F'0T (21).

As can be seen from Fig. 5C, the output vo of the integrator (441) is
The voltage increases instantaneously by a certain amount. This constant voltage is 1
The negative slope part of 0 corresponds to the constant charge extracted from the integrator (441) by the stepper pulses. The slope of the sawtooth wave or output vo is constant, and this slope is determined by the current o and the capacitance of the capacitor (61).If the stepper pulse interval is constant, i.e. no paper speed error should occur. For example, the charge extracted from the integrator (44) by one stepper pulse is canceled by the current generator 0 during exactly one stepper pulse. As a result, the S/H circuit (461) does not generate a correction signal. 0 If the interval of the stepper pulses is not constant, i.e. if there is a paper speed error, the current IO will increase or decrease the charge taken out of the integrator (441) by one stepper pulse during one stepper pulse. Accordingly, the output vO of the integrator (4I!J has a waveform as shown in FIG. 5C, and the S/H circuit (461) as shown in FIG. 5E) is supplied according to the length. output VC is the compensation voltage and 1
7 is generated at its output terminal OUT. 8/) The output vc of one circuit (4G) is applied to a bandpass filter (not shown) to remove undesired signal frequencies before being fed to the Y-axis deflection circuit (4) in FIG. It may be L7.

As can be seen from the above description, the present invention can provide a compensating means with a very simple structure that can compensate for short-term paper speed errors. Moreover, its error detection sensitivity is quite high, linearly proportional to changes in paper speed, and its response is also very fast. The present invention can be easily adapted to a variety of marking devices with fixed or widely controllable paper speeds without any readjustment.Furthermore, by using components with high precision tolerances, calibration is possible. No adjustment required. Although only one preferred embodiment of the present invention has been described above, those skilled in the art will readily understand that modifications and variations can be made without departing from the gist of the present invention. Further, the present invention includes such modifications and changes. For example, the direction of movement of the charge pump circuit and current source relative to each integrator may be swapped.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional line-scan storage device, FIG. 2 is a block diagram showing the basic principle of the improved compensation means of the recording device according to the invention, and FIG. 3 is a block diagram showing the basic principle of the improved compensation means of the recording device according to the invention. FIG. 4 is a block diagram showing an embodiment of the improved compensation means of the recording apparatus, and the improved compensation means (40) of the recording apparatus according to the present invention is a charge pump circuit (4 is a current source, +441 is a Integrator, (4G) is a Zumble hold circuit, (40 is a DC stabilization circuit)

Claims (1)

[Claims] A recording apparatus comprising a recording medium, a means for moving the recording medium, and a recording means for recording an input signal by scanning in a direction perpendicular to the moving direction of the recording medium, the recording apparatus generating pulses in response to the speed of the recording medium. , controls an integrator that is charged and discharged by the respective outputs of a constant current source and a charge pump circuit operated in response to the pulse, and deflects the recording means in the moving direction in response to the output of the integrator. , A recording device having the following characteristics: compensation for speed errors of the recording medium.