JPH0110218Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sensor case mounting structure that enables a single type of detector to detect the presence of recording paper and print timing in a thermal printer using a lined-head type thermal head. be.

This type of thermal printer often uses a combination of a motor and gears to drive the paper feed roller to continuously feed the paper, resulting in lower noise and lower power consumption than when using a step motor. , it has the advantage of being able to achieve low cost. In this case, the detection of the print timing is performed using either shaft of the gear transmission mechanism that transmits the rotation of the motor to the paper feed roller, specifically, the drive shaft of the motor that fixes the gear, or the gear that receives power transmitted by the gear. A detector equipped with a reflective photo sensor detects the blade of a position detection plate fixed to one of the shafts of the paper feed roller to be fixed (if an intermediate gear is provided, the shaft to which the intermediate gear is fixed may be used). One dot line is printed when the number of signals emitted by the detector detecting the wing reaches a predetermined number. By employing such a print timing detection means, the printing operation and paper feed speed can be accurately synchronized, and the dot line spacing (one print line is printed with several dot lines) can be kept constant to print characters of a constant size. It is possible to print.

In addition, in thermal printers, printing without recording paper will damage the paper feed roller, etc., so printing is performed only when the presence of recording paper is detected. To detect the presence of recording paper, a hole is formed in the recording paper guide plate provided in the housing and guides the recording paper between a paper feed roller and a thermal head that presses against the paper feed roller, and this hole is used to detect the reflection. This is done using a detector equipped with a type photo sensor.

However, in the past, the two types of detection described above were performed using different types of detectors, which posed a problem in reducing costs.

This invention is intended to solve the above problems.
The object of the present invention is to provide a sensor case mounting structure that allows a single type of detector to detect the presence of recording paper and print timing.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a thermal printer 1 to which the present invention is applied.
In the figure, 2 is a housing, 3 is a recording paper guide plate, 4 is a head support plate, 5 is a leaf spring, 6 is a gear transmission mechanism, and 7 is a reflective photo sensor unit. The illustrated photo sensor unit 7 is for detecting printing timing, and a similar unit is provided on the back side of the recording paper guide plate 3 for detecting the presence of recording paper (the installation method will be described later).

The recording paper guide plate 3 has a shape shown in detail in FIG. 2, and is provided with a hole 8 for detecting the presence of recording paper.

The head support plate 4 has shaft portions 9 integrally provided at both ends of its base, and is rotatably supported by both side plates 2a, 2b of the housing 2. The thermal head 10 is fixed as shown in FIG.

The base of the leaf spring 5 is fixed to the housing 2, and the tip of the leaf spring 5 biases the head support plate 4 to press the thermal head 10 against the paper feed roller 11 as shown in FIG.

The gear transmission mechanism 6 includes gears 12, 13, 14, and 15, as shown in detail in FIG. The gear 12 is fixed to a drive shaft 17 of a motor 16 provided in the housing 2, and the gears (intermediate gears) 13 and 14 are fixed to an intermediate shaft 18 rotatably supported by the side plate 2a of the housing 2. The gear 15 is fixed to a shaft 19 of a paper feed roller 11 that is rotatably supported by the housing 2 . The gear 12 meshes with the gear 13, and the gear 14 meshes with the gear 13.
meshes with gear 15. Therefore, the motor 16
The rotation of the paper feed roller 11 is carried out via a gear transmission mechanism 6.
transmitted to.

The recording paper (thermal paper) 40 is guided by the recording paper guide plate 3 as shown in FIG.
0 and the paper feed roller 11, and the motor 1
The paper is transported between the thermal head 10 and the paper feed roller 11 by a paper feed roller 11 driven by the paper feed roller 6 . Printing on the recording paper 40 is performed by operating the thermal head 10 at a predetermined time, and one line of multi-dot lines is printed.

Next, details of the photo sensor unit 7 that detects the printing timing of the thermal head 10 and the presence of recording on the recording paper guide plate will be explained.

The photo sensor unit 7 is shown in FIGS. 4 and 5.
As shown in the figure, a reflective photo sensor 20 and a sensor case 2 that houses the reflective photo sensor 20
1 and more. The reflective photo sensor 20 has a sixth
As shown in detail in the figure, two optical cables 25 for output and two optical cables 26 for input are connected in a cylindrical body 24 having an output window 22 and an input window 23, so that the light that enters the optical cable 25 is connected. The light that exits from the exit window 22 and enters from the entrance window 23 is transmitted to the optical cable 2.
The end face of the cylindrical body 24 with the exit window 22 and the entrance window 23 is exposed to one end face 21a of the sensor case 21, and the terminal of each optical cable is inserted into the side surface of the sensor case 21. It stands out. On the other end surface 21b of the sensor case 21,
A flange 29 with a slit 27 and a rivet fixing hole 28 is formed.

The photo sensor unit 7 having such a configuration is
It can be used for detecting the presence of recording paper and for detecting print timing.
We will explain the installation procedure for the.

When using the photo sensor unit 7 for detecting printing timing, use the rivet fixing hole 28.
Attach using. In this case, as shown in FIGS. 3 and 7, a hole 31 for inserting the rivet 30 is provided at a predetermined position on the side plate 2a of the housing 2 (the side plate 2a and the hole 31 constitute a first fixing part), Flange 2
Rivet 3 in hole 28 and hole 31 for fixing rivet 9
By inserting and tightening the photo sensor unit 7, the photo sensor unit 7 is fixed to the side plate 2a, and in this state, the reflective photo sensor 20 of the photo sensor unit 7 is fixed.
is positioned at a position facing a blade 33 provided on a position detection plate 32 fixed to the drive shaft 17 of the motor 16. When installing the photo sensor unit 7, a positioning protrusion 34 is provided at a position away from the rivet fixing hole 28 on the end surface 21b of the sensor case 21, and the protrusion 34 is inserted as shown in FIGS. 1 and 7. Hole 35 provided in side plate 2a
By fitting the photo sensor unit 7 into the sensor case 21, the sensor case 21 can be reliably positioned and the photo sensor unit 7 can be attached easily and accurately.

The printing timing is detected by detecting the wing 33 of the position detection plate 32 using the photo sensor unit 7 installed as described above.

The reason why the position detection plate 32 is fixed to the drive shaft 17 as described above is because the gear 12 has a relatively small diameter, and the photo sensor unit 7 is attached to the left side of the gear 12 on the side plate 2a, as shown in FIG. This is because there is sufficient space for installation and storage.

When the photo sensor unit 7 is used for detecting the presence of recording paper, it is attached using the slit 27. In this case, as shown in FIG. The photo sensor unit 7 is fixed by fitting the slit 27 into the piece 36, but since the engaging piece 37 is shaped to be press-fitted into the narrow part 38 of the slit 27, the engaging piece 37 fits into the narrow part 38. 38 and the end surface 3 of the engaging member 37
7a is engaged with the stepped portion 39 of the slit 27, and the photo sensor unit 7 is securely positioned and fixed.
In this state, the reflective photo sensor 20 housed in the photo sensor unit 7 faces the hole 8 on the back side of the recording paper guide plate 3. Therefore, the presence of recording paper can be detected by the photo sensor unit 7.

As described above, according to the present invention, two photo sensor units of one type are fixed to the first and second fixing parts provided in the housing to adjust the print timing.
Since the presence of recording paper can be detected individually, costs can be reduced compared to the conventional method using two types of detectors.

[Brief explanation of the drawing]

The drawings show an embodiment of the sensor case mounting structure according to the present invention. Figure 1 is a perspective view of a thermal printer to which the present invention is applied, and Figure 2 is a side view showing how to attach a photo sensor unit for detecting the presence of recording paper. Figure 3 is a plan view showing details of the gear transmission mechanism and how to install the photo sensor unit for printing timing detection, Figures 4 and 5 are perspective views of the photo sensor unit as seen from both end faces, respectively, and Figure 6 The figure is a perspective view of the reflective photo sensor, and FIG. 7 is a side view of the vicinity of the mounting portion of the print timing detection photo sensor unit on the housing. In the figure, 1 is a thermal printer, 2 is a housing, 2
a, 2b are side plates, 2c is a bottom plate, 3 is a recording paper guide plate, 6 is a gear transmission mechanism, 7 is a photo sensor unit, 8 is a hole for detecting the presence of recording paper, 10 is a thermal head, 11 is a paper feed roller, 12 ,13,14,
15 is a gear, 16 is a motor, 17 is a drive shaft, 20
is a reflective photo sensor, 21 is a sensor case, 2
1a and 21b are end faces, 27 is a slit, 28 is a rivet fixing hole, 29 is a flange, 30 is a rivet, 31 is a rivet insertion hole, 32 is a position detection plate, 33 is a wing, 36 is an engaging piece, and 37 is a Engaging member (second fixing part), 38 is a narrow part, 39 is a stepped part,
40 is recording paper.

Claims (1)

[Scope of utility model registration request] A linear dot type thermal head that is in pressure contact with the rubber roller prints on the recording paper that is transported along a recording paper guide plate provided in the housing by a paper feed roller driven by a motor through a gear transmission mechanism, and In a thermal printer that detects the presence of recording paper and print timing by using a hole provided in the recording paper guide plate and a position detection plate fixed to one of the shafts of the gear transmission mechanism, a reflective photo sensor is installed in the sensor case. A flange having a slit and a rivet fixing hole is formed on the end face of the photo sensor exposure side and the reflecting side of the sensor case, and the photo sensor unit is arranged in the housing so that the photo sensor is placed in the position. a first fixing part for fixing the sensor case with a rivet inserted into the rivet fixing hole so as to face the detection plate;
a second fixing portion that engages with the slit of the sensor case and fixes the sensor case so that the photo sensor faces the hole in the recording paper guide plate; A sensor case mounting structure characterized by being configured so that it can be detected by a photo sensor unit.