JPH0413169Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a daisy wheel type printing device, and more particularly to a home position detection device for the daisy wheel and carriage of this type of printing device. .

[Conventional technology]

In this type of printing apparatus, it is necessary to set and detect reference positions (referred to as home positions) of each of the daisy wheel and carriage in order to control the printing operation.

Conventionally, this has been done by providing dedicated sensors (including switches) (not shown) for each of these home position detections.

[Problem that the invention attempts to solve]

However, the conventional method described above has the disadvantage that it is expensive because it requires separate sensors and associated circuits for each home position detection.

The present invention was developed in view of the problems of the conventional examples as described above, and it is possible to detect the home position of the daisy wheel and the home position of the carriage with a single sensor, and it is possible to detect both the home position of the daisy wheel and the home position of the carriage at low cost. The purpose is to be able to separate and recognize the location.

[Means for solving problems]

Therefore, in the present invention, a home position detection arm is provided for each of the daisy wheel and carriage, and by making the reflectance of each detection arm different, the optical sensor and processing circuit process the information as two pits. However, even if two home position detection arms exist within the sensor detection range, the configuration is such that the two positions can be reliably separated and recognized.

[Example] The present invention will be described below based on an example. Figs. 1a and 1b show a side view and a plan view of the main parts of a detection device according to the present invention. 1 is daisy wheel, 2
is a stepping motor for driving the rotation of the daisy wheel, and the sensor 3a is a reflective type having a light emitting part.
It is fixed to the carriage 6 (Fig. 2). The daisy wheel home position detection arm 4 is
A carriage home position detecting arm 5 is fixed at the center of the daisy wheel 1 and rotates together with the wheel 1, and a carriage home position detection arm 5 is fixed near the left end of the carriage movement on the printer frame side. The reflectance of the portions of the arms 4 and 5 facing the sensor 3a is as follows:
They are formed to be different from each other by changing their surface color, material, or surface condition.

FIG. 2 is a perspective view of the main part of this embodiment as viewed from the platen side, and the direction in which the sensor 3a faces each of the detection arms 4 and 5 is shown perpendicular to that in FIG. 1. 6 is a carriage, and 7 is a printing hammer.

Figures 3a, b, c, and d are respectively shown. Figure a shows the detection arm 4 not in the daisy wheel home position, Figure b shows it in the same position as above, and Figure c shows the detection arm 5 in the carriage position. FIG. d is an explanatory perspective view showing a state in which the detection arms 4 and 5 are in their respective home positions, facing the sensor 3a, and detecting the position. It is.

FIG. 4 is a binary circuit diagram for determining each home position, and FIG. 5 is a flowchart of home position detection processing.

In FIG. 4a, a photocurrent I _L is reflected by each home position detection arm 4 or 5 and output from the light receiving part of the reflective sensor 3a.
has a characteristic that changes depending on the reflectance of the detection object, so this current is converted into a voltage via a load resistor R _L and compared with different reference voltages Vref ₁ and Vref ₂ by comparators 8 and 9, respectively. Particularly 2
You can get pit information. FIG. 4b shows the respective voltage levels. The detection level can be changed by controlling Vref ₁ and Vref ₂ .

Next, the detection processing operation will be explained using FIG. The conditions for this figure are as follows.

Comparator 8 (2 ⁰ ) and comparator 9 (2 ¹ ) of the binarization circuit
The output is 11 if both a in Fig. 3 are not in the home position, 01 if the daisy wheel in Fig. 3 b is in the home position, and the same as in Fig. 3 c when the carriage is in the home position. If the daisy wheel and carriage of d are both in the home position, the value is 00. Figure 3 d is the same as Figure 3 c.
00 indicates that the sensor is detecting the home position detection arm 5 of the carriage, and since the home position detection arm 4 of the daisy wheel overlaps the detection arm 5 of the carriage, it is different from c in the same figure. This is because it is not possible to detect the difference between the two. The home position of the carriage is placed on the left side of the printing device, and the first step of detecting the home position by moving the sensor 3a to the left is the home position of the carriage. Further, CW in the figure is an abbreviation for clockwise direction.

11, first move the daisy wheel so that the home position detection arm 4 of the daisy wheel, which cannot be detected when both are in the home position in FIG. 3d, is detected first; When 01 is detected, the movement of the daisy wheel is stopped, and the carriage home position detection arm 5 is immediately moved.
Move the carriage so that it detects 00, and when it detects 00, the setting of both home positions is complete.

If it is 01 at the start, the daisy wheel is already at the home position, so the second carriage home position setting operation is executed. Also, if it is 00 at the start (Fig. 3 c, d)
), the carriage is already at the home position, so the carriage is moved from the home position detection range to the right outside the detection range and the daisy wheel's home position detection arm 4 is detected (the carriage is moved to the home position detection range). (one step to the right from the detection range). As a result, if the state is as shown in c in the figure at the start, the above movement of the carriage causes the daisy wheel and the carriage to become in the state 11, as shown in a in the figure, where neither is in the home position.
Furthermore, if the state is as shown in d in the figure at the start, the daisy wheel in b in the same figure will be in the state 01 in the home position. When the number becomes 11 due to the movement of the carriage, the home position setting operation of the first daisy wheel is executed to detect 01. Thereafter, the carriage is moved one step to the left to set the carriage to the home position, thereby completing the setting of both home positions. Note that the error processing at the right end of the figure shows the processing state when some kind of contradiction occurs.

[Other Examples]

In the above embodiments, a case has been described in which the reflective sensor is fixed to the carriage, but it may also be fixed to the machine frame side of the printing device.

Furthermore, the same principle can be applied by using a transmissive sensor instead of a reflective sensor and changing the transmittance of each arm.

[Effect of idea]

As explained above, according to the home position detection device of the present invention, by changing the reflectance or transmittance of the two detection arms, daisy-wheel type printing can be performed using one reflective sensor or transmission sensor. After detecting one of the home positions of the daisy wheel and carriage of the device, it is possible to detect the home position of the other, making it possible to set both continuously, which eliminates unnecessary operations. can be detected at low cost.

[Brief explanation of the drawing]

Figures 1a and b are a side view and a plan view of the main parts of the detection device according to the present invention, Figure 2 is a perspective view thereof, and Figure 3a
-d are perspective views explaining the detection/non-detection state of each home position, FIG. 4 is an example of a binarization circuit, and FIG.
The figure is a flowchart of the home position detection process. DESCRIPTION OF SYMBOLS 1... Daisy wheel, 3a... Reflective sensor, 4... Daisy wheel home position detection arm, 5... Carriage home position detection arm, 6... Carriage, 8, 9... Comparator.

Claims (1)

[Claim for Utility Model Registration] Two home position detection arms formed with different reflectances or transmittances for the daisy wheel and carriage, and two home position detection arms facing each home position detection arm, or a reflective sensor or a transmissive sensor whose output changes depending on the amount of transmitted light, and an output value of the sensor that determines whether both of the home position detection arms are at the home position or whether the daisy wheel or carriage is two binarization circuits that determine three states: one home position detection arm is at the home position, and the other or both home position detection arms are at the home position; According to the state determined by the binarization circuit,
A daisy wheel type printing device characterized by comprising a control means for moving a daisy wheel or a carriage and controlling both home position detection arms to be located at the home position.