JPH04173253A - Testing device for dot impact printer - Google Patents

Abstract

PURPOSE:To detect a trouble in a print head in a short time by measuring kinematic friction. CONSTITUTION:A testing device for a dot impact printer comprises a load sensor 2 for measuring load in a part to be measured 91 as a moving part of a print head, a pulse motor 1 for reciprocating the load sensor 2 vertically by displacing the position of the part to be measured 91, and a central processing unit 7 for sending signals to a controller 6 so as to make the pulse motor 1 perform those operations and storing a load quantity to be outputted from the load sensor 2 and a displacement quantity of the part to be measured 91 in a memory 8 serially. The load of the part to be measured 91 is measured by reciprocating the load sensor 2 with the pulse motor 1 so as to form a hysteresis curve by making the displacement quantity of the part to be measured 91 a horizontal axis and making the load quantity detected at the load sensor 2 a vertical axis. Based on the curve, a kinematic friction of the moving part of the print head and peripheral parts thereof is obtained. By measuring the kinematic friction which is the largest cause of trouble in the print head, a trouble in the print head can be detected assuredly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an operation test device for a print head of a dot impact printer, and measures the dynamic friction between a movable part and its surrounding parts to reduce future troubles of the print head. The purpose of the present invention is to provide a test device for a dot-in-back I printer that can be detected in time, and includes a load sensor that measures the load at a predetermined part of a part to be measured, which is a movable part of a print head, and a load sensor that is controlled by the control device. a pulse motor that moves the load sensor in a vertical direction; a signal is sent to the control device so that the pulse motor performs a predetermined operation; an output signal from the load sensor is input; and the output signal is sequentially stored in a storage device. It is characterized by having a central processing unit for storing information.

[Industrial application field]

The present invention relates to an operation testing device for a print head of a dot impact printer.

Dot impact printers are equipped with dot pins for printing dots that form characters, and these dot pins pop out using electromagnetic force and transfer ink to the paper by hitting the ink ribbon on the surface of the paper. ing.

During the manufacturing process of this print head, there are variations in the precision of the parts that make up the print head, so friction (hereinafter referred to as kinetic friction) acts between the movable part and its surrounding parts.

If this kinetic friction is large, the kinetic friction will become even larger due to metal powder generated when the dot pin wears due to friction during printer operation, resulting in a delay in tracking the pin movement and blurred printing, or the tip of the pin may touch the ink ribbon. It may get caught and break.

For this reason, after the product is completed and before it is shipped, the print head is tested to prevent problems with the print head after shipping.

[Conventional technology]

Conventional tests for the print head of dot impact printers include a dynamic characteristic test in which the printer is operated and the speed and pressure of the dot pins in the print head are measured, and a print run in which characters are printed continuously for a long period of time and the characters are checked for fading. test, or by inserting a subezer between moving parts and other parts;
There were tests to confirm whether there was any contact.

[Problem to be solved by the invention]

Most of the print head troubles in dot impact printers are caused by dynamic friction.

13= However, since these methods do not directly measure this dynamic friction, they cannot eliminate problems that occur after a long period of time.

It is an object of the present invention to provide a dot impact printer testing device that can detect future problems with print heads in a short time by measuring dynamic friction.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In view of the above problems, the present invention is configured as follows. As shown in FIG. 1, a load sensor 2 that measures the load on a part to be measured 91 that is a movable part of the print head;
A pulse motor 1 that vertically reciprocates the load sensor 2 while displacing the measured part 91;
A central processing unit 7 sends a signal to the control device 6 to perform these operations, and sequentially stores the load amount output from the load sensor 2 and the displacement amount of the measured part 91 in the storage device 8.
It is characterized by having the following.

1 Effect] FIG. 2 is a diagram showing the difference in the relationship between the amount of displacement and the amount of load depending on the presence or absence of dynamic friction of the movable part of the print handle. The horizontal axis is the amount of displacement of the part to be measured 91, and the vertical axis is the amount of load on the part to be measured 91. Graph (a) is a graph when the amount of displacement increases, and graph (b) is a graph when the amount of displacement decreases. This is a graph of the time.

Figure 2 (a) is a graph when no dynamic friction acts on the movable part, and the amount of displacement and the amount of load are proportional. The graphs (b) match when moving. This graph (41 ports) only shows the properties of the springs connected to the dot pins.

FIG. 2(b) is a graph when dynamic friction acts on the movable part.

As the amount of displacement increases, dynamic frictional force is added to the load due to the repulsive force of the springs, so the graph (a) changes from the one shown in Figure 2 (a).
) The load amount relative to the -6= position is larger than the graph (a) in Figure 2(a), so the curve is located above the graph (a) in Figure 2(a).

Conversely, when the amount of displacement is decreased, the direction of motion is reversed and the direction of the dynamic friction force is also reversed, so the load becomes equal to the repulsive force of the spring minus the internal dynamic friction. Therefore, the graph (b) is a curve located below the graph (b) of FIG. 2(a).

Therefore, the graphs are different when the amount of displacement increases and when it decreases, and a hysteresis curve is drawn as shown in FIG. 2(b). The area surrounded by this hysteresis curve is proportional to the magnitude of dynamic friction, and when the amount of displacement or load is constant, the width of each hysteresis curve is also proportional to the magnitude of dynamic friction. are doing.

Therefore, the dynamic friction force can be determined from this hysteresis curve.

The present invention measures the load on a part to be measured 91 while reciprocating the load sensor 2 by a pulse motor 1, and then uses the amount of displacement of the part to be measured 91 as the horizontal axis and calculates the amount of load detected by the load sensor 2. A hysteresis curve is formed as the vertical axis, and the dynamic friction between the movable part of the print head and its surrounding parts is determined from the curve.

〔Example〕

First, the printing gutter used in this embodiment will be explained with reference to FIG.

FIG. 3 shows a moving coil print head.

In the front view, 90 is a coil assembly which contains an electromagnet, has a tiger I pin 95 on the lower side of its tip, and a temporary spring 93 connected to the frame on the other end. Further, on the upper side of the tip, when the pin 95 pops out to the driver 1 and then returns, it has a rear head 911 that hits an elastic body and stops the recoil of the entire coil assembly. 94 is Pingite,
A hole is provided to prevent the tosoto pin 95 from protruding from a predetermined portion.

Next, in a side view, a permanent magnet 92 is fixed to the frame, and when an electric current flows through the electromagnet built in the coil assembly 90, the coil assembly is actuated by this permanent magnet.

The operation of the moving coil type print head configured as described above will be explained.

When a current flows through the electromagnet built in the coil assembly 90, a magnetic force is generated between the electromagnet and the permanent magnet 92, and the coil assembly 90 moves downward. Then, the dowel pin 95 provided on the lower side of the tip pops out downward through the hole in the pin guide 94. Then, when the current flowing through the electromagnet is turned off, the elasticity of the plate spring 93 returns it to its original position. At this time, the back of the head 911 is placed against an elastic body (not shown) to prevent the coil assembly 90 from vibrating due to the reaction.

An embodiment of the present invention using such a moving coil type print head is shown in FIG.

In this figure, 2 is a load sensor, and its rod 2
1 is in contact with the back of the head 911 which is the part to be measured of the print head 9, and its output signal is amplified by an amplifier 1q-0]. Reference numeral 1 denotes a pulse motor that displaces the pushing portion 91 via the load sensor 2.

In this embodiment, three sets each of the pulse motor 1, the load sensor 2, the amplifier 101, and the print head 9 are used, and these are controlled to operate in exactly the same way by the control device 6.

4 is a pulse motor, and a stand 5 on which a print head 9 is mounted,
It is used to adjust and move the back of the head 911 in the horizontal direction so that it is directly below the mouth yt'' 21 of the load sensor 2. 7 is a central processing unit that causes the pulse motors 1 and 4 to operate as described above. The signal is sent to the control device 6, and the output signal from the load sensor 2 is inputted via the amplifier 101 and digitized, and then sequentially stored in the storage device 8.

A display 201, a printer 202, and an external storage device 81 are each connected to the central processing unit 7. The display 201 is for displaying test results, and the printer 202 is for printing test results. The storage device 81 is for storing test results in a storage medium such as a floppy disk.

The operation of the test apparatus configured in this way will be explained. The operations for all three print heads are the same, so only the operation for one print head will be explained here.

First, the stand 5 on which three print heads are mounted is placed on the lot 2 where the back part 911 of each print head is the load sensor 2.
Adjust it using the pulse motor 4 so that it is directly below 1.

Of course, the position of the load sensor 2 at this time is the rod 2
The pulse motor 1 is
It has been raised by

After positioning is completed, rotate pulse motor 1,
Gradually lower the load sensor 2. And rod 21
Measurement starts after the head contacts the back of the head 911. Even after the start of measurement, the load sensor 2 is gradually lowered while displacing the push-in portion 91.

Since the total length of the load sensor 2 including the rod 21 does not change, the displacement of the load sensor 2 is equal to the displacement of the pushing portion 91. Therefore, depending on the rotation speed of the pulse motor 1, the pushing part 91
Find the amount of displacement. This amount of displacement is input from the central processing unit 7 to the storage device 8 and is stored together with the output signal of the load sensor 2.

Once the coil assembly 90 has been displaced to the lowest position within its operating range, the pulse motor 1 is rotated in the opposite direction, and the load sensor 2 is gradually pulled up.

Then, similarly to ζ, the amount of displacement of the back of the head 911 and the amount of load measured by the load sensor 2 are sequentially stored in the storage device 8.

When the load amount becomes zero, the measurement is finished and the pulse motor 1
Rotate as it is and pull up the load sensor 2. Then, the coil assembly 90 next to the coil assembly 90 that has been measured so far is placed directly below the loft 21. Then, the measurement just performed is also performed on the adjacent assembly 90.

These steps are repeated for all coil assemblies 90.

Once the measurement is complete, the next step is to tally the data.

= 11- For each coil assembly 90, read out the displacement amount and load amount stored in the storage device 8, and plot the displacement amount on the horizontal axis,
Create a graph with the load amount as the vertical axis and form a hysteresis curve. The magnitude of dynamic friction is determined from the maximum width of the hysteresis curve (hereinafter referred to as hysteresis width) when the amount of displacement is constant.

FIG. 5 is a diagram showing the relationship between a print running test and a hysteresis width.

In this graph, when the hysteresis width is 14 to 16 g, the number of dots when a scratch defect occurs changes greatly.

Here, the line with a hysteresis width of 20 g is set as the pass/fail judgment line, and those with a width larger than this are judged as defective and readjusted, and those with a smaller width are judged as acceptable.

The test results are then displayed on the display 201, printed on the printer 202, and, if necessary, saved on a floppy disk or the like using the external storage device 81.

Although Embodiment 1-1 has been described below, the present invention is not limited to Embodiment 1-1.

For example, in the above embodiment, the magnitude of dynamic friction is determined from the hysteresis width of the hysteresis curve, but dynamic friction may also be determined from the area of the portion surrounded by the hysteresis curve. In addition, in the above description, the test results are aggregated when all measurements are completed, but individual coil assemblies 90
The test results may be aggregated after the measurement, and the measurement may be carried out while the test results are aggregated. Also, by using a plurality of central processing units 7,
If the results are collected at the same time as the measurement, the test can be performed in a short time, and if the number of load sensors 2 is increased and more print heads 9 are measured at the same time, even more tests can be performed. It is. Furthermore, in this embodiment, the print head 9 is mounted directly on the stand 5, but a plate with a recess for mounting the print head 9 is further placed on the stand 5, and at the same time as the test ends, By replacing the next board on which a plurality of print heads 9 are mounted, it is possible to test many print heads in an even shorter period of time.

In addition, in this embodiment, moving coil 4
- Although the test method was explained using a type print head, it is also applicable to wire printer print heads with high-density mounting of dot wires and other types of print heads with dynamic frictional resistance structures such as dot impact type dot wire guides. It is also possible to conduct the test in the same manner.

〔Effect of the invention〕

As described above, according to the present invention, by measuring dynamic friction, which is the most important cause of troubles in the print head of a dot impact printer, future troubles in the print head can be detected more reliably.

Therefore, the accuracy of testing is improved, and parts that may cause failures due to changes over time can be prevented from being shipped, which greatly contributes to improving the performance and reliability of printer devices for users.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention. Figure 2 shows the difference in the relationship between displacement and load. FIG. 3 is a structural diagram of a moving coil type print head. FIG. 4 is a diagram showing an embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the printing running test and the hysteresis width. In the figure, 1. ,,Pulsmoke 290. Load sensor 609. Control device 713. Central processing unit 810. Storage device 911. Print head 91,, part to be measured (Al Change U'# v Jitf/l F 2nd (b) Figure 3 Example of surface flash Soj ・Do to tree T diagram

Claims (1)

[Claims] 1. A load sensor (2) that measures the load of a part to be measured (91), which is a predetermined movable part of the print head (9); and a load sensor (2) that is controlled by a control device (6); (2)
a pulse motor (1) that moves the motor in a vertical direction; and a pulse motor (1) that sends a signal to the control device (6) to cause the pulse motor (1) to perform a predetermined operation, and inputs an output signal from the load sensor (2). and a central processing unit (7) that sequentially stores the output signal in a storage device (8). 2. The load sensor (2) is controlled by the pulse motor (1).
) is sent to the control device to reciprocate, forming a hysteresis curve with the displacement of the movable part to be measured (91) as the horizontal axis and the load detected by the load sensor (2) as the vertical axis. 2. The dot impact printer testing device according to claim 1, further comprising a central processing unit that performs the following steps.