JPH0615878A - Printing device - Google Patents

Abstract

PURPOSE:To ensure that print quality is stable, the ease of operation of a printing device is improved and thereby, mass-productivity is enhanced due to a consequent functional amelioration by making variably controllable the timing of energizing a dot head in response to a potential detected using a head voltage detection means. CONSTITUTION:First, the actual value of a wire flying time variation in a dot head 2 due to a power supply voltage variation is determined. Then the variation characteristics of (power supply voltage-wire flying time) are calculated. After that, the offset balance between the variation characteristics and the variation characteristics of (power supply voltage-dot head transport speed) of a transport motor 1 is corrected. To achieve this correction, a correction time for the energization timing of a head 2 for each potential is determined and is previously entered in a storage circuit 7 in terms of software. That is, if a printing position is adjusted using a power supply voltage and the rotating speed of a motor 1 as the pivotal value of actual use conditions, a power supply voltage, if changed after adjustment, is detected by a head voltage detection circuit 6, and the value is transmitted to a head drive control circuit 8. Finally, the energization timing correction time of the head 2 which corresponds to the detected voltage is calculated using the circuit 8 based on data from the circuit 7 to adjust the drive of the head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus which forms a character or a symbol by carrying out printing while carrying a dot head in both directions and repeating the printing operation a plurality of times.

[0002]

2. Description of the Related Art Conventionally, in the printing apparatus as described above, when printing is performed in both directions at position A as shown in FIG. 2, the wire of the dot head reaches the printing surface from the start of energization of the dot head. Since the distance L from the energization start position to the dot head to the A position for printing is determined by the flight time up to and the transport speed of the dot head, when the dot head is transported in each of the B and C directions, The generation positions of the energization timing pulses Tn and Tn ′ are adjusted so that the distance is 2L. However, the power source for the dot head and the motor for driving the dot head is generally shared, and if the voltage of the power source changes after the above-described print position adjustment, the print position deviates from the A position.

This will be described with reference to FIG. 8 which shows both the relationship of <power supply voltage-dot head transport speed> change characteristics and <power supply voltage-wire flight time> change characteristics. After performing the printing position adjustment at the center value (Typ. Value) of the range, the change in the flight time of the wire shows the characteristic of a with respect to the change in the voltage of the power supply, and the change in the transport speed of the dot head , As a transport drive motor,
When a DC motor having no rotation speed control means is used, the characteristic of b is exhibited, while a DC motor having a rotation speed control means constructed as shown in the block diagram of FIG. 5 or a pulse motor is used. This is because when the rotation speed is controlled to be constant, the change rate between the flight time of the wire and the transport speed of the dot head with respect to the voltage change of the power source is deviated in order to show the characteristic of c.

The factor is that the flight time of the wire is dominated by the acceleration component, so that the square value of the rate of change becomes the change characteristic of the flight time of the wire with respect to the rate of change of the power supply voltage. The dot head carrying speed in the conventional example shows a characteristic that the rate of change is substantially equal to the power supply voltage when speed control of the carrying drive motor is not performed, and the rotation speed of the carrying drive motor is controlled to be constant. This is because the case shows no change characteristics. Since the change characteristics of the dot head conveyance speed and the conveyance drive motor rotation speed inevitably coincide with the change in the power supply voltage, each speed in the text will be expressed as the same meaning hereinafter. To do.

Here, a DC having no rotation speed control means
A case of using the motor will be described with reference to FIG. 6. When the power supply voltage is increased after the above-described print position adjustment, the flight time of the wire becomes relatively slow with respect to the transport speed of the dot head. The distance from the energization of the dot head to the printing point at Ln and Tn ′ is L + α, and the printing position shift in both directions is 2α. Further, when the voltage of the power supply is lowered, the flight time of the wire is relatively fast with respect to the transport speed of the dot head. Therefore, the distance from the energization of the dot head at the pulse Tn and Tn ′ to the printing point is L. -Β
Therefore, the printing position shift from both directions becomes 2β.

On the other hand, when a DC motor or pulse motor having a rotation speed control means is used to control the rotation speed of the motor to a constant value with respect to changes in the power supply voltage, an example is shown in FIG.
In the explanation, when the power supply voltage is increased after the above-mentioned print position adjustment, the flight time of the wire becomes relatively fast with respect to the transport speed of the dot head.
The distance from the energization of the dot head to the printing point at n'is L-α ', and the printing position shift from both directions is 2α'. Also, when the power supply voltage is lowered, the flight time of the wire becomes relatively slow with respect to the transport speed of the dot head, so the distance from energization of the dot head with pulses Tn and Tn ′ to the printing point is L + β. The print position shift from both directions becomes 2β '.

As described above, in the conventional printing apparatus, the printing position shift is unavoidable for the above reason regardless of whether the rotation speed control of the dot head transport drive motor is performed or not. Therefore, the print position adjustment described above is performed at the center value in the actual allowable voltage range of the printing device, and the print position deviation amount is evenly distributed to minimize the absolute amount. After allowing or allowing each printing apparatus to be combined with a dedicated power source, the above-described print position adjustment is performed, and the voltage change after the adjustment is avoided to prevent the print position deviation.

As described above, in order to maintain the best print quality without print position deviation, there is no choice but to set the power supply voltage to the same voltage as when the print position is adjusted. , Voltage adjustment or print position adjustment is required for each power source used, and even for the dedicated power source of each printing device,
Since it is necessary to adjust the printing position again, it is troublesome and there is a problem in mass productivity. Further, when replacing the printing device during actual use, it is necessary to adjust the printing position again or adjust the voltage again, which is inconvenient.

[0009]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve the above-mentioned problems, and its purpose is to stabilize the print quality, improve the usability of the printing apparatus, and improve the mass productivity by improving the function. Is to raise.

[0010]

In order to solve the above problems, in a printing apparatus according to the present invention, a dot head drive circuit controls head drive control means for controlling energization timing of the dot head, and application to the dot head. Head voltage detection means for detecting voltage, and variably controllable energization timing to the dot head in accordance with the potential detected by the voltage detection means. Also, the head drive control means is characterized by having a storage means that associates the voltage applied to the dot head with the energization timing to the dot head.

[0011]

With the above-described means, the energization timing of the dot head is variably controlled so as to correct the deviation in the rate of change between the transport speed of the dot head and the flight time of the dot head wire in response to changes in the power supply voltage. can do.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the block diagram of FIG. FIG. 1 is a block diagram showing a transport driving motor for the dot heads 2 and a drive control means for the dot heads 2. The configuration of the drive control circuit is shown in FIG.
A head voltage detection circuit 6, a memory circuit 7, and a head drive control circuit 8 are added to the configuration of the conventional drive control circuit shown in FIG.

First, referring to the block diagram 1, a case where the rotation speed of the transport driving motor 1 is controlled to be constant will be described. When a DC motor is used as the transport drive motor 1,
The rotation speed of the motor is detected by a motor speed detection circuit 5 such as a tacho generator and an encoder, and the information is transmitted to a motor rotation speed control circuit 4 so that the rotation speed becomes constant in the motor rotation speed control circuit 4. The speed control is performed by adjusting the drive condition (current value or energization time) of the transport drive motor 1. Also, the transport drive motor 1
When a pulse motor is used for the motor, the motor rotation speed is controlled by the motor rotation speed control circuit 4 at a constant drive pulse frequency, and the constant rotation speed is not affected by changes in the power supply voltage. Has been maintained.

Here, by grasping the actual value of the flight time change of the wire of the dot head 2 due to the change of the power supply voltage, 8
The change characteristic a of <voltage of power supply-time of flight of wire> shown in the figure is calculated, and the amount of deviation between the change characteristic and the change characteristic c of <power supply voltage-conveying speed of dot head> of the conveyance driving motor 1 is corrected. Therefore, the energization timing correction time of the dot head 2 is determined for each potential, and the storage circuit 7 is preliminarily set by software.
Input to.

For example, the power supply voltage and the transport drive motor 1
When the rotation speed of is set to the center value of the actual use condition and the print position adjustment described above is performed, if the power supply voltage changes after the print position adjustment, the voltage is detected by the head voltage detection circuit 6 and the information Is transmitted to the head drive control circuit 8. In the head drive control circuit 8, the energization timing correction time of the dot head 2 corresponding to the detected voltage is calculated from the data of the storage circuit 7, and the drive condition (energization timing correction time) of the dot head 2 is adjusted. is there.

An example will be described with reference to FIGS. 3 and 4. When the power supply voltage is increased after the above-described print position adjustment, the flight time of the wire is relatively fast with respect to the transport speed of the dot head, and the dot Since the distance from the energization of the head 2 to the printing point is L-α ', the energization timing of the dot head 2 is delayed by α', and when the power supply voltage is lowered, the dot head transport speed is reduced. Since the flight time of the wire is relatively delayed and the distance from energization of the dot head to the printing point is L + β ', the timing of energization of the dot head 2 is advanced by β'.

Further, in the block diagram 1 of the present invention, in the case where the rotation speed of the transport driving motor 1 is not controlled, the actual value of the change in the flight time of the wire of the dot head 2 due to the change in the power supply voltage is grasped. Fig. 8 <Power supply voltage-
In order to determine the change characteristic a of the flight time of the wire> and correct the deviation amount between the change characteristic and the change characteristic b of the <supply voltage-conveying speed of the dot head> of the conveyance drive motor 1, the dot is calculated for each potential. The energization timing correction time of the head 2 is determined and input to the storage circuit 7 in advance by software.

An example will be described with reference to FIGS. 3 and 4. When the power supply voltage is increased after the printing position adjustment described above, the flight time of the wire becomes relatively slow with respect to the carrying speed of the dot head, and the dot Since the distance from energization to the head 2 to the printing point is L + α, the timing of energization to the dot head 2 is advanced by α, and when the power supply voltage is lowered, the wire speed is reduced with respect to the transport speed of the dot head. Since the flight time is relatively fast and the distance from the energization of the dot head to the printing point is L-β, the energization timing of the dot head 2 is delayed by β.

By carrying out the above-mentioned head drive control, the dot head 2 is corrected in order to correct the deviation in the amount of change between the rotation speed of the transport drive motor 1 and the flight time of the wire of the dot head 2 due to the change in the power supply voltage. It is possible to variably control the energization timing of.

[0020]

In the printing apparatus according to the present invention, the dot head drive circuit has head drive control means for controlling the energization timing of the head, and head voltage detection means for detecting the voltage applied to the dot head. According to the potential detected by the voltage detecting means, the timing of energizing the dot head can be variably controlled. Further, the head drive control means is characterized by having a storage means for associating the applied voltage of the dot head with the energization timing of the dot head. According to the present invention, the transport drive is performed by the change of the applied voltage to the dot head. The rotation speed of the motor 1 for
Since it is possible to variably control the energization timing of the dot head 2 in order to correct the deviation of the amount of change from the flight time of the wire of the dot head 2, the printing position due to the voltage change after the printing position adjustment described above is performed. It is possible to stabilize the print quality of the printing device without causing the deviation.

Further, since the voltage adjustment for each power source or the reprinting position adjustment is unnecessary, the usability of the printing apparatus is improved, and the workability at the time of evaluation and inspection is reduced, thereby improving the mass productivity. Is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a motor / head drive control circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a print position adjusting method.

FIG. 3 is an explanatory diagram of print position adjustment during head energization timing control in the embodiment of the present invention.

FIG. 4 is an explanatory diagram of print position adjustment during head energization timing control in the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a motor / head drive control circuit in a conventional example.

FIG. 6 is an explanatory diagram of a print position shift when a motor rotation speed is not controlled in a conventional example.

FIG. 7 is an explanatory diagram of occurrence of print position deviation during constant motor rotation speed control in a conventional example.

FIG. 8 is a graph showing a change characteristic of a dot head carrying speed and a wire flight time with respect to a change in power supply voltage.

[Explanation of symbols]

 1 Motor for Transport Drive 2 Dot Head 3 Motor Drive Circuit 4 Motor Rotational Speed Control Circuit 5 Motor Rotational Speed Detection Circuit 6 Head Voltage Detection Circuit 7 Memory Circuit 8 Head Drive Control Circuit 9 Head Drive Circuit

Claims (2)

[Claims] 1. A printing apparatus, such as a printing apparatus, which prints while carrying a dot head bidirectionally and repeats the operation a plurality of times to form a character, a symbol, etc. Head drive control means for controlling the energization timing to the head, and head voltage detection means for detecting the voltage applied to the dot head, corresponding to the potential detected by the head voltage detection means,
A printing apparatus, wherein the timing of energizing the dot head is variably controllable. 2. The printing apparatus according to claim 1, wherein the head drive control unit includes a storage unit that associates a voltage applied to the dot head with a power supply timing to the dot head.