JP2929335B2 - How to adjust the print density of a dot printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the printing density of a dot printer, and more particularly, to a method for adjusting a hammer adjusting device mounted on a hammer bank.

[0002]

2. Description of the Related Art Each print hammer constituting a hammer bank of a line printer is provided with an adjusting mechanism using an adjusting screw or the like so that the print density can be varied. , Give an appropriate adjustment amount, check the printing result, if there is a difference with the target,
The above operation was repeated for each hammer, and as a result, the sensory adjustment was performed so that the concentration was sufficiently high and uniform. The print density of the hammer changes according to the adjustment amount, and usually has a positive correlation. However, since the front plate and the platen are present, an area where the adjustment is not possible after a certain adjustment position (for the positive adjustment amount). , A region in which the density is sharply reduced), and this is a problem when it is automated. FIG.
Indicates the state in which the print density changes due to the rotation of the adjustment screw. From a to b, the print density gradually increases as the adjustment screw is rotated, but beyond that, the front plate, in fact the platen , The tip of the hammer pin comes into close contact with the ink ribbon and printing is not performed like W even when a printing operation is performed. Next, when the adjusting screw is rotated in the opposite direction, the density changes as c → d. The state in which the printing is not performed is referred to as “white spots”, and when automation is performed, it is necessary to adjust the value to an optimum value without causing white spots. FIG. 2 shows an automatic print density adjustment device developed by the present inventors to automate the print density adjustment work of a line printer.
The printing paper 3 fed from the supply reel 2 by the capstan 1 is wound around a platen 4 through a guide, and reaches a take-up reel (not shown) via a measuring head 5. ing. On the other hand, a printing section is a portion for printing on the printing paper 3 and includes a shuttle mechanism (not shown) for reciprocating the printing paper 3 in a direction perpendicular to the paper feed, and a cylindrical platen 4 and an adjustable body. It is composed of a certain hammer bank 6. Reference numeral 7 denotes a control device using a personal computer, which controls each part, stores a signal detected by the measurement head unit 5, compares the signal with a set target density, and when the detected density value does not reach the set target density. , A correction amount, and adjuster 8 according to the calculated value.
Is given a rotation command, and the adjustment screw 9 is
Is adjusted by changing the angle of the hammer to adjust the protruding state of the hammer pin HP to adjust the print density. FIG. 3 shows a flowchart of the print density adjustment. First, the mounted screw hammerbank 6 or the print density adjuster is relatively laterally moved (in the embodiment, the hammerbank 6 is laterally moved), and the adjustment screw 10 is set. After the adjustment bit 9 is opposed to the adjustment bit 9 and the adjustment bit 9 is advanced to engage with the adjustment screw 10, printing is started. After printing the predetermined pattern as shown in FIG. 4, the paper is fed just below the measuring head 5 to measure the print density of the print pattern. When the difference between the measured print density and the target set print density is extremely small, the adjustment is terminated. After the adjustment bit 9 is retracted, the process proceeds to the next hammer adjustment. In other cases, an amount corresponding to the difference is instructed to the adjustment unit as an adjustment amount. For example, the adjustment amount is given by the following equation. Adjustment amount = K × (target-measured value) where K: constant or variable This amount is given to the adjustment unit as a command value, and the adjustment screw 10 is rotated by the adjustment bit 9. The target concentration is reached by repeating the above cycle as one cycle, usually several cycles. However, in the print density adjusting device shown in FIG. 2, when the adjusting screw 10 is adjusted, in the case of a hammer exhibiting the density characteristics as shown in FIG. 5, a blank state occurs as shown in FIG. 6 during hammer pin adjustment. In such a case, the control device 7 determines that the adjustment is insufficient and adjusts the adjuster 8 in a direction to increase the print density. Accordingly, an object of the present invention is to provide an automatic density adjustment method for detecting a white spot during adjustment, exiting from the state, and adjusting to a target print density.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a hammerbank of a dot printer, and has various functions of printing operation, paper feeding, and printing density measurement. And an adjusting unit that drives an adjusting mechanism of the hammer on the hammer bank, and stores a print density measurement result,
In a print adjustment device of a dot printer equipped with a control device that controls the operation of each unit based on the calculation result, a plurality of printings are performed on the inspection printing paper by changing the adjustment position little by little,
The print density is measured, a density gradient is calculated from the measured value, an adjustment amount is calculated from the density gradient and the print density, and the adjustment unit is controlled based on the value. .

The printing density adjusting device shown in FIG.
As shown in FIG. 4, since only one density is measured, it cannot be distinguished whether the current adjustment position is the area having the positive correlation or the blank area.
In the blank area, the adjustment amount is given in the wrong direction. In the present invention, when adjusting each time of the hammer,
By performing a plurality of printings by giving a predetermined minute amount of adjustment change and measuring the same, not only the density but also the density gradient is calculated from the input values in each adjustment cycle, and even if these two pieces of input information are blank, The adjustment operation of the hammer having one local maximum value to the optimum point is correctly continued even in the region.

FIG. 7 shows an embodiment of the present invention. Since the hardware other than the function of the control device 71 is the same as that of the previously developed device shown in FIG. 2, the description of that portion will be omitted. FIG. 8 shows a flowchart of the adjustment operation of the embodiment apparatus shown in FIG. 7, and the printing paper 3 is printed in the initial state at step 21 as shown in FIG.
The first printing) is performed, and in Step 23, printing n2 (the n2th printing) in which the adjustment screw 10 is slightly rotated from the initial state.
Is performed, the paper is fed (step 24), and the densities D1 and D2 are measured by the measuring head 5. Next, in step 27, the average density Dnm

(Equation 1) And concentration gradient a

(Equation 2) If the average density Dnm does not satisfy the condition of the following equation (3) (step 28), the adjustment is completed, and the process proceeds to the next hammer adjustment. DT−e ≦ Dnm ≦ DT + e (3) On the other hand, when the expression (3) is satisfied and the concentration gradient is a> O,
In step 30, the density difference Dd from the target value is calculated, and further, the adjustment amount x = Dd × c is calculated. If equation (3) is satisfied, but a> O is not satisfied, in step 32, the target value and the target value are calculated. Of the density difference Dd and the adjustment amount x = Dd × d, the adjustment screw 10 is rotated according to each adjustment amount x, and the above operation is repeated so that the target density is obtained. Make adjustments.
Note that k (k> o), c, d (d> o), and e (e ≧ o) are constants. In the example described above, two prints with different screw adjustment amounts are performed, and the print density is measured. However, three or more types of prints and print densities may be measured. However, in practice, only two types of printing and its density measurement are sufficient. FIG. 10 shows the adjustment process of a certain hammer for each cycle on a density characteristic diagram with respect to an adjustment position. At the time of adjustment, this characteristic is completely unknown. Now, in the first cycle, the densities D1 and D2 measured in two adjacent states where the difference between the adjustment positions is 10 deg are 0.22D and 0.25D, respectively.
Therefore, the average density Dn = 0.235D and the density gradient a is (0.25-0.22) /10=0.003
(D / deg). (Refer to Fig. (B).) Then, the difference from the adjustment target DT = 0.4 Dd = 0.16
5, if the adjustment amount x is x = Dd / a, x =
Since 55 deg is obtained, a rotation command is issued in the 55 deg forward direction. Similarly, the second cycle is completed, and at the time of the third cycle, the density gradient becomes a <o in the calculation result (white spot detection). At this time, a negative adjustment amount is first given (here,-
7.5 deg), return to the normal region, and adjust to -10 deg in the fourth cycle to converge to the target concentration.

As described above, according to the present invention, the control device 71 using the conventional device and configuration and having different software is used.
By performing a plurality of different printing and density measurements, and calculating and processing a plurality of density measurement values for each adjustment cycle, the characteristics of white spots in hammer adjustment where the density characteristics for the adjustment amount are completely unknown In addition, it is possible to provide an adjustment method capable of promptly responding.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of white spots in a dot printer.

FIG. 2 is a diagram showing a configuration of a main part of a print density adjusting device developed earlier.

FIG. 3 is a flowchart of print density adjustment of the apparatus shown in FIG. 2;

FIG. 4 is a diagram showing a printing state of the apparatus shown in FIG.

FIG. 5 is a diagram showing an adjustment amount of an adjustment screw of a certain head and a change in density.

6 is a diagram for explaining a problem in the case where the hammer having the characteristic shown in FIG. 5 is adjusted in print density by the apparatus shown in FIG. 2;

FIG. 7 is a diagram showing a configuration of an example of the present invention.

FIG. 8 is a flowchart of print density adjustment of the apparatus shown in FIG. 7;

FIG. 9 is a diagram showing a printing state in the embodiment of the present invention.

FIG. 10 is a diagram showing a state and actual data when a print density adjustment of a certain hammer is performed by the apparatus according to the present invention shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capstan 2 Supply reel 3 Printing paper 4 Platen 5 Measurement head 6 Hammerbank 7,71 Controller 8 Adjuster 9 Adjustment bit 10 Adjustment screw 11 Keyboard

Claims (1)

(57) [Claims] 1. A hammerbank of a dot printer is mounted, and various functions of a printing operation, a paper feed, and a printing density measurement are provided.
And an adjustment unit for driving a hammer adjustment mechanism on the hammer bank, and a print adjustment device for a dot printer including a control device for storing a print density measurement result and controlling the operation of each unit based on a calculation result. A plurality of printings are performed by changing the adjustment position little by little on the printing paper, the printing density is measured, a density gradient is calculated from the measured value, and an adjustment amount is calculated from the density gradient and the printing density. A print density adjusting method for a dot printer, wherein the adjusting unit is controlled based on the value.