JPS63112175A - High-accuracy paper feed controlling mechanism - Google Patents

Abstract

PURPOSE:To obtain a high-accuracy paper feed controlling mechanism, by providing a controlling part for outputting a balance point address for a stepping motor, and a minute-rotational feeding circuit for the motor for outputting an exciting current to each phase of the motor according to the balance point address sent from the controlling part. CONSTITUTION:A controlling part 4 outputs a balance point address for a stepping motor 3, and the address is supplied to a minute-rotational feeding circuit 6. The circuit 6 supplies currents iA, iB to a phase A and a phase B of the stepping motor 3 according to the balance point address, thereby varying a balance point of the motor 3 and sequentially rotating the motor 3 minutely, whereby arbitrary setting can be performed in spite of a rough mechanical feed pitch. By the combination of the stepping motor connected directly to a platen with the minute-rotational feeding circuit, the feed quantity per step can be made to be finer than a conventional feed accuracy, and high image quality can be obtained even with a serial printer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-precision paper feed control mechanism for a serial printer.

[Conventional technology]

Conventionally, serial printers have mainly recorded characters such as ANK. For this reason, the rotation angle accuracy of the platen mechanism is obtained by a combination of a step motor and a gear, and the feeding accuracy is quite rough, about 0.2 mm per step (converted to paper feeding amount).

[Problem that the invention seeks to solve]

However, as a recent trend, users have been requesting print records of not only characters such as ANK but also line figures, images, and the like. When recording such an image with a conventional serial printer, the step motor's one-step rotational feed accuracy becomes coarse due to the limited mechanical feed pitch (λ) and the gear bank. There has been a major problem in that the feeding accuracy of the platen is poor due to the influence of rush, etc., and the recorded image itself has horizontal streaks and uneven density, resulting in a significant deterioration in output image quality.

An object of the present invention is to provide a high-precision paper feed control mechanism that solves this problem.

[Means for solving problems]

The present invention is based on a high-precision paper feeding system for serial printers that print character images, etc. by horizontally moving the print head left and right. 2
In the II mechanism, a platen for winding and feeding the paper, a step motor directly connected to the platen and for rotating the platen with high precision, and an equilibrium point of the step motor according to the number of steps corresponding to the paper feed target position. a control unit that outputs an address; a memory element that outputs an excitation current value to each phase of the step motor according to the equilibrium point address from the control unit; and a memory element that outputs an exciting current value to each phase of the step motor according to the output value of the memory element. The present invention is characterized in that it includes a step motor minute rotation feeding circuit including an amplifier for applying voltage.

〔Example〕

The high-precision paper feed control mechanism will be described in detail below with reference to the illustrated embodiment.

FIG. 1 is a schematic diagram showing a high-precision paper feed control mechanism of the present invention, and FIG. 2 is a block diagram showing an example of the configuration of the step motor minute rotation feed circuit shown in FIG. 1. FIG. 3 is a diagram showing the step motor static propulsion characteristics at each equilibrium point of the step motor. FIG. 4 is a diagram showing a specific configuration of the low-pass filter shown in FIG. 2.

In FIG. 1, 1 is a platen for winding and feeding the paper 2, 3 is a two-phase step motor directly connected to the platen 1 to rotate the platen 1 in steps with high precision in order to feed the paper with high precision, and 7 is a print head for printing character images, etc. on paper 2 fed by platen 1, and moves horizontally from side to side. Reference numeral 4 denotes a control unit which outputs the equilibrium point address value of the step motor 3 via a line 5, and supplies it to the minute rotation feed circuit 6 of the step motor 3. This minute rotation feed circuit 6 supplies a current iA+ to each of the A phase and B phase of the step motor 3 according to the equilibrium point address from the control unit 4.
18, the equilibrium point of the step motor 3 is changed, and the step motor 3 is sequentially rotated minutely, thereby making it possible to arbitrarily set the feed pitch (λ) regardless of the coarse mechanical feed pitch (λ). In other words, when currents of a certain magnitude are passed through each of the A-phase and B-phase, there is always an equilibrium point depending on the combination of the current values, and the position of this equilibrium point exists only for the excitation current of the A-phase and B-phase, and the machine It is unrelated to the actual feed pinch (λ).

FIG. 2 is a block diagram showing an example of the configuration of the minute rotation feed circuit 6. As shown in FIG. The minute rotation feed circuit 6 receives the address value U of the equilibrium point of the step motor 3 given from the control unit 4, and outputs the current value to be given to each of the A phase and B phase of the step motor 8A. ,
8. , D/A converters 9A, 'Js that convert digital No. 13 indicating output values ga and ga of ROMs 8A and 8B into analog signals, and D/A converters 9A and 9. The output value hA
, h, low-pass filter 10A, 10g and low-pass filter 10A, which cut off frequency components higher than the Nyquist frequency (1/2T) of It consists of amplifiers 11A and 118. The low pass filter is
As shown in Figure 4, the resistors R,,R, and the capacitor C
,,C2, and a differential amplifier A.

Incidentally, the position of the equilibrium point of the step motor 3 can be arbitrarily set by appropriately combining the A-phase current value and the B-phase current value, regardless of mechanical feed pinch. In other words, when a certain amount of current is passed through each of the A-phase and B-phase, there is always an equilibrium point depending on the combination of the current values, and the position of this equilibrium point depends only on the excitation current of the A-phase and B-phase. Independent of mechanical feed pitch.

Therefore, when the equilibrium point position due to a certain combination of currents is set as a reference address (address value O), the amount of deviation from that point can be set as the equilibrium point address of the step motor, and ROMs 8A and 8B contain information about this equilibrium point. A combination of current values corresponding to the address is stored. However, the combination of the A-phase current value and the B-phase current value is set so that the maximum static thrust is constant. For example, if the mechanical pinch of the step motor 3 is λ, the equilibrium point position of the step motor 3 when a current of +0.1 ampere is applied to both the A phase and the B phase is set as the reference address, and furthermore, at this time, If the maximum static thrust of
8 a +0.1 ampere (address O) to O1
A current of up to O amperes (address λ/8) is applied to the A phase, and +0.1 ampere (address 0
) to +0.1×F7 amperes (address λ/8) are stored in sequence in accordance with the address of the equilibrium point. FIG. 3 shows this situation, with a reference address (address value 0) determined by a certain combination of currents and an equilibrium point address U, which is the amount of deviation from that point.

It shows the static thrust characteristics at u', u''.

Further, the rotational feed position of the step motor 3 is similarly given as a positional deviation from the reference address.

In other words, the above-described operation is repeated while the reference address is reset every mechanical pinch (λ) of the step motor. In this way, when the mechanical pitch of the step motor is λ, conventionally the rotational feed accuracy could only be λ or λ/2 at best, but by using the present invention, the balance stored in the ROMs 8A and 81 can be Rotational feed accuracy can be improved by the point address.

As explained above, the combination of a step motor directly connected to the platen and a minute rotational feed circuit allows the feed amount per step to be one order of magnitude finer than conventional feed accuracy, for example 0.02 mm per step. I was able to do it. As a result, the conventional problem of deterioration in output image quality due to horizontal streaks or density unevenness in the recorded image itself is eliminated, and even serial printers can obtain high image quality at a low price. The effect is significant because of the price.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the high-precision paper feed control mechanism of the present invention, Fig. 2 is a block diagram of the minute rotation feed circuit, and Fig. 3 shows the step motor stationary propulsion characteristics at each equilibrium point of the step motor. 4 are diagrams showing a specific configuration of the low-pass filter shown in FIG. 2. 1...Platen 2...Paper 3...Step motor 4...Control unit 6...Minute rotation feed circuit 7...Print head 8A, 8B...ROM

Claims (1)

[Claims] (1) A high-precision paper feed control mechanism for a serial printer that prints character images, etc. by moving the print head horizontally from side to side, includes a platen that wraps and feeds the paper, and a platen that is directly connected to the platen and rotates the platen with high precision. a step motor for moving the paper feed, a control section that outputs an equilibrium point address of the step motor according to the number of steps corresponding to the paper feed target position, and a control section that outputs an equilibrium point address of the step motor according to the number of steps corresponding to the paper feed target position; A high-precision paper feed control mechanism comprising: a memory element that outputs an excitation current value; and a step motor minute rotation feed circuit that includes an amplifier that applies a current to the step motor in accordance with the output value of the memory element.