JPH0541374Y2 - - Google Patents

Description

[Detailed Description of the Invention] {Industrial Field of Application] The present invention relates to a recording instrument equipped with a detection means for detecting the presence or absence of recording paper using a reflective sensor.

{Prior art} In recording instruments, recording paper (end of recording paper)
It is well known that a reflective sensor is used as a detection means for detecting the presence or absence of an object. This detection means arranges a detection member that detects when there is no recording paper opposite a reflective sensor, runs the recording paper between the sensor and the detection member, and collects the reflected light from the recording paper at a certain threshold. In addition, when there is no recording paper, the reflected light from the detection member is detected as a low-level output. Conventionally, as such a detection means, a reflective sensor 3 is arranged on the circumference of the platen 1 with respect to the recording paper 2 which is wound around the round platen 1 and moves as shown in FIG. That is, conventionally, the presence and absence of recording paper are detected at the same distance.

Figure 4 shows the output characteristics of a reflective sensor, where the horizontal axis represents the distance L (mm) between the sensor and the target.
, and the sensor output V is plotted on the vertical axis. curve
T0 indicates the initial high level output, T1 indicates the high level output after approximately 5 years, T2 indicates the initial low level output, and T3 indicates the change in the low level output after approximately 10 years. As shown by these curves, in the reflective sensor, the degree of change in output level over time is greater for high level output than for low level output. Therefore, if the threshold level is set to a relatively high value such as Vt1, a detection error may occur due to changes over time.

When considering the lifespan of a reflective sensor, it is necessary to suppress the low level to a value as low as possible, for example, several mV or less, in order to keep the possibility of detection errors low. Therefore, when high level and low level are detected at the same distance as in the past, the material of the low level detection member placed opposite the sensor must be made of a certain material, such as matte rubber, due to the characteristics of the sensor. It will be limited to.

In addition, even if such a detection means is placed outside the circumference of the round platen, if a rubber material is used to detect the low level, the passage route of the recording paper will be stabilized and the distance to the sensor will be maintained with good accuracy. It is difficult to do so.

{Problem to be solved by the invention} This invention was devised to solve such problems, and when detecting recording paper using a reflective sensor, the output level difference between the presence and absence of recording paper is made as large as possible. Even if the high level output decreases due to the sensor's lifespan, a sufficient level difference between the high level and the low level is ensured, and the discrimination threshold is kept as low as possible, while at the same time the distance to the sensor is relatively rough. However, the object of the present invention is to provide a recording instrument equipped with a detection means capable of ensuring an output difference.

{Means for solving the problem} In order to achieve the above object, the present invention includes a reflective sensor, a detection member arranged opposite to the reflective sensor to detect when there is no recording paper, and a reflective sensor. and an intermediate member disposed between the reflective sensor and the intermediate member, and the recording paper is configured to run between the reflective sensor and the intermediate member so that the reflective sensor detects the presence or absence of the recording paper. A recording paper detecting means is provided. Examples will be described in detail below.

{Embodiment} FIG. 1 is a block diagram of an embodiment of a recording paper detecting means used in a recording instrument according to the present invention. In the figure, 10 is a round platen which has sprockets 11 at both ends as shown in FIG. 2 and rotates in the direction of arrow Y, and 12 is its rotation axis. The sprocket 11 is made of black resin (for example, polycarbonate). Reference numeral 20 denotes recording paper, and although folded recording paper is shown here, roll paper may also be used. 30
is a back plate attached to the side plate 40 of the recording paper cassette; 50 is a leaf spring; its base 51 is attached to the base plate 52;
is in contact with the back plate 30. Recording paper 20
passes between this back plate and the free end 53 of the leaf spring, in which case a back tension is provided by the leaf spring. This tension is set so as not to interfere with the feeding of the recording paper 20, including environmental conditions.

60 is a reflective sensor assembly, 61 is a sensor, 62 is a cover, 63 is a base, and 64 is a bracket. The sensor 61 is attached to a base 62 and covered with a cover 63.
In order to prevent reflection from the cover 63, a hole is provided in the portion of the cover 62 facing the sensor 61. Such a sensor assembly 60
The sensor 61 is arranged so as to face the sprocket 11 on the platen 10 at a distance L3. Note that the thickness of the cover 62 that covers the sensor 61 is assumed to be L2, and the distance between the cover and the back plate 30 is assumed to be L1. FIG. 3 shows a schematic configuration of the sensor assembly 60 showing the relationship between these distances L1, L2, and L3. The operation of the device of the present invention having such a configuration will be explained as follows.

The recording paper 20 set in the recording paper cassette stock section 40 passes between the back plate 30 and the leaf spring 50 and between the reflective sensor assembly 60 and the sprocket 11, and then passes through the sprocket pin 1.
3, it is continuously sent out at a constant speed over the platen 10 in the direction of arrow Y, and the measured value is recorded by a recording mechanism (not shown) disposed on the platen. Here, light emitted from the sensor 61 constituting the reflective sensor assembly 60 passes through a hole in the cover 62 and is reflected by the recording paper 20 if there is one, and the reflected light is received by the sensor 61. . In this case, the distance between the sensor 61 and the recording paper 20 is
As shown in the figure, L1+L2 becomes L1+L2, and the output V of the sensor 61 at that time is the curve T0 and (L1
+L2).

When the recording paper 20 continues to be fed and the last end of the recording paper 20 passes in front of the sensor 61, the sensor 6
1, the recording paper in front runs out, so the distance L3 (>
Capture the outer periphery of sprocket 11, which is separated by (L1+L2)). In this case, the output of the sensor 61 is the fourth
As shown by the intersection of L3 and curve T2 in the figure,
The value will be extremely low. Therefore, the threshold level for determining the presence or absence of the recording paper 20 can be set as low as Vt2. By lowering the threshold level in this way, even if the high level output decreases due to aging, a sufficient level difference between the high level and the low level can be ensured.

{Effects of the present invention} As explained above, in the present invention, a reflective sensor and a sprocket, which is a detection member placed opposite to the reflective sensor and which detects when there is no recording paper, are used to detect the presence of recording paper. Since it is configured to be separated from the sensor position and efficiently utilize the characteristics of the reflective sensor, it is possible to ensure a sufficient level difference between high and low levels even when considering the sensor's lifespan (changes over time). This allows stable recording paper detection. As a result, according to the present invention, it is possible to obtain a recording instrument having a recording paper detecting means that has a degree of freedom in selecting the detection material for detecting the absence of recording paper.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a main part of an embodiment of a recording meter equipped with a recording paper detecting means according to the present invention, FIG. 2 is a block diagram of a platen used in the meter of FIG. 1, and FIG.
Figure 1 is a diagram showing the distance relationship between the reflective sensor assembly used in the meter and the detection member, Figure 4 is a diagram for explaining the characteristics of the recording paper detection means used in the Figure 1 meter, and Figure 5 is a diagram for explaining the characteristics of the recording paper detection means used in the meter. The figure is a configuration diagram of the main parts of a conventional recording paper detection means. 10...Platen, 11...Sprocket, 2
0...Recording paper, 30...Intermediate member, 60...Reflective sensor assembly, 61...Reflective sensor, 6
2...Cover.

Claims (1)

[Scope of utility model registration request] A reflective sensor, a sprocket arranged opposite to the reflective sensor to detect when there is no recording paper, and a leaf spring arranged between the reflective sensor and the sprocket to apply back tension to the recording paper. What is claimed is: 1. A recording instrument comprising a recording paper detecting means, comprising a plate, and configured to run recording paper between the reflective sensor and the back plate and detect the presence or absence of the recording paper with the reflective sensor.