JPH04249184A - Scan head - Google Patents

Abstract

PURPOSE:To provide a scan head featuring the provision of a paper sensor in a manner independent of other parts to thereby lighten the assembly operation and reduce the cost. CONSTITUTION:A paper sensor 40 is connected to a circuit board 30 on a thermal print head substrate 10 consisting of a heating board 20 and the circuit board 30 and the sensor 40 and a platen 70 are spaced from each other in such a manner that the light emitting and receiving surfaces of the sensor 40 face toward the platen 70. The light is emitted from a light emitting element of the sensor 40 to paper 100 or the platen 70 and, by the quantity of the reflected light sensed by a light receiving element thereof, it is detected whether or not the paper 100 exists.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning head, such as a print head or a contact image sensor, which is mounted on a support plate and pressed against a platen.

0002

2. Description of the Related Art As scanning heads that are used while being pressed against a platen, thermal print heads are known for printing, and contact type image sensors are known for reading. Among these, to explain the thermal print head as an example, the thermal print head itself has a heating resistor as a printing element arranged on a ceramic substrate in the scanning direction. Normally, instead of applying direct pressure to the thermal print head itself (hereinafter referred to as the thermal print head board) to press it against the platen, the thermal print head board is mounted on a support plate that also serves as a heat sink. This support plate is pressed against the platen.

0003

[Problems to be Solved by the Invention] By the way, devices such as facsimiles and printers equipped with thermal print head boards are equipped with paper sensors that detect the presence or absence of thermal paper, general paper, etc. (hereinafter referred to as paper). There is usually one. The paper sensor is provided separately from the thermal print head substrate, and metal fittings, openings, etc. for mounting the sensor are provided in the paper running section within the device, and the sensor is mounted at the relevant position. That is, the paper sensor and the thermal print head board are completely separate parts, and each is assembled and wired independently within the device.

However, although both the paper sensor and the thermal print head board are parts installed in the paper traveling section, the paper sensor is a separate part from the thermal print head board, so the sensor is not installed inside the device. Not only must a dedicated mounting part be provided, but also dedicated wiring and wiring connectors must be provided. Therefore, there are problems such as an increase in the number of parts, necessitating extra assembly work for the equipment, and increasing material and manufacturing costs.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a scanning head that can reduce the assembly work and cost associated with handling a paper sensor as a separate component.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the scanning head of the present invention has a paper sensor disposed at a position facing the platen (Aspect 2), or a heating element on the scanning head. Mounting a paper sensor element together with multiple heating element driving elements provided as a
It is characterized by aspect (■).

[0007] Since the paper sensor is integrated in both of the scanning heads of the embodiments (1) and (2) above, the sensor can be incorporated at the same time by simply mounting the scanning head in the device, and the above problems are solved at once. Ru. In the scanning head of the present invention, the paper sensor referred to in the above aspect (1) or (2) only needs to be able to detect whether or not paper is attached to the platen as in the conventional case, and generally includes a light emitting element (LED etc.) and a light receiving element (photo). (transistor, etc.)
The presence or absence of paper is detected based on the amount of light reflected by the paper or platen.

[0008]The sensor used in aspect (2) is a single component in which a light-emitting element and a light-receiving element are integrated in advance, and this component is placed at a position facing the scanning head at a predetermined distance from the platen. and connects to circuitry on the scan head. In the case of aspect (2), the light emitting and light receiving elements are mounted on the wiring pattern along with multiple heat generating element driving elements (usually ICs) mounted on the scanning head according to the wiring pattern, so chip parts are not used as the light emitting and light receiving elements. is preferred. At this time, it is preferable to provide a light shield between both elements so that the light from the light emitting element does not directly enter the light receiving element and the light receiving element malfunctions.

The mounting position and number of paper sensors in the platen axis direction (scanning direction) may be appropriately selected depending on detection conditions such as paper end detection and paper size detection. In addition, the sensor wiring connector and drive circuit are
It is only necessary to add it to the wiring connector or board circuit of the scanning head, and there is no need to provide a new sensor connector or circuit.

[0010] Since the paper sensor detects the presence or absence of paper based on the amount of light reflected, it is desirable that the platen facing the sensor be made of a material with high light absorption properties in order to prevent malfunctions as much as possible. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The scanning head of the present invention will be explained below based on embodiments. The scanning head shown in FIGS. 1 and 2 is a thermal print head substrate, of which FIG. 1 is a side view and FIG. 2 is a perspective view. This embodiment relates to the above-mentioned mode (2), in which a paper sensor is arranged on the thermal print head substrate so as to face the platen. The thermal print head board 10 is composed of a heat generating board 20 and a circuit board 30. However, since the substrates 20 and 30 are thin and weak, they are shown integrally with a reinforcing plate in the drawings.

The heating substrate 20 has heating resistors 21 extending in the scanning direction of thermal printing, and the number of resistors 21 is large depending on the printing resolution (dot number). are collectively connected to the driving IC 22 in a circuit pattern, and generate heat according to the print pattern on the paper (thermal paper). The drive ICs 22 arranged in parallel are protected by a resin mold 23.

The circuit board 30 is connected to the circuit pattern of each driving IC 22, and both boards 20 and 30 are attached to the board 30 with screws or the like (not shown) so that the heat generating board 20 and the circuit board 30 will not be disconnected. The cover 31 is pressed at the mutual connection. A paper sensor 40 is placed on this cover 31, and a lead wire 41 is connected to the substrate 3.
Connected to 0. Of course, it goes without saying that the substrate 30 includes a drive circuit for the sensor 40. In this embodiment, as can be seen from FIG. 2, two sensors 40 are provided at appropriate intervals. Furthermore, a connector 50 for controlling all the elements (including the sensor 40) on the substrates 20 and 30 is attached to the lower surface of the substrate 30.

The thermal print head board 10 made up of these parts is usually glued and fixed on a support plate 60 which also serves as heat radiation, but the adhesion is limited to the center part of the board 10 and both ends are not fixed. It becomes. This is because consideration is given to the fact that the substrate 10 and the support plate 60 generally have different coefficients of thermal expansion. In FIG. 1, the support plate 6
A projecting piece 61 that rotatably supports the rotating shaft 71 of the platen 70 is attached to the end of the platen 70 . When the platen 70 is installed on the protruding piece 61 of the support plate 60, the sensor 40 is close to the platen 70, and the sensor 40 and the platen 7
The interval from 0 is set so that the presence or absence of the paper 100 can be detected without malfunction.

Detecting the presence or absence of the paper 100 is carried out as is well known in itself, since when the paper 100 is supplied to the platen 70, the paper 100 normally exhibits a white color.
The light reflectance is high, and when the light emitted from the light emitting element of the sensor 40 is reflected by the paper 100 and returns to the light receiving element, the amount of light does not attenuate much. On the other hand, if the paper 100 is not attached to the platen 70, the platen 70 is usually black in color and has light absorbing properties, so the amount of light decreases significantly. Thereby, the presence or absence of the paper 100 can be detected.

The embodiment shown in FIGS. 3 and 4 is the embodiment (2) above, in which a paper sensor made of a chip component is mounted on the thermal print head substrate 10 (heat generating substrate 20) together with a heating element driving element. This thermal print head board 10 has a light emitting element 25, a light receiving element 26, and a light receiving element 26 at a position where the driving ICs 22 of the heat generating resistor 21 are arranged in parallel on the heat generating board 20. A paper sensor 40 composed of a light shielding body 27 of
is mounted on the circuit pattern together with the driving IC 22 by die bonding, wire bonding, or the like. Of course, the chip parts 25 to 27 of the sensor 40 include IC2.
2 as well as a resin mold 23. However, although only one set of the sensor 40 consisting of three chip components is shown in FIG. 3, a plurality of sets may be provided between the ICs 22 at appropriate intervals depending on the detection conditions. As is clear from FIG. 4, when the platen 70 is attached to the protruding piece 61 of the support plate 60, the sensor 40 faces the platen 70, and the same effect as described above can be obtained. In this embodiment, since the paper sensor 40 is mounted on the heat-generating substrate 20, the sensor is smaller than that in the previous embodiment, and automation in the manufacturing process line becomes easier.

[0017]

[Effects of the Invention] As explained above, the scanning head of the present invention integrates the scanning head and the sensor by using the paper sensor in the configuration (1) or (2), so that the scanning head can be installed in equipment such as facsimile machines and printers. In this case, there is no need to provide a dedicated sensor mounting part, wiring, or wiring connector in the device.

[0018] Therefore, the work of assembling a scanning head having a paper detection function into a device is simplified, and the cost of materials such as parts and manufacturing costs can be reduced. In addition, by adding the detection signal from the sensor to the print control signal of the scanning head, it is also possible to directly control the scanning head depending on the presence or absence of paper.

[Brief explanation of the drawing]

FIG. 1 is a side view of a scanning head according to an embodiment of the present invention when attached to a support plate.

FIG. 2 is a schematic perspective view of the scanning head shown in FIG. 1;

FIG. 3 is a partially omitted plan view of a scanning head according to another embodiment of the present invention.

FIG. 4 is a partially omitted side view of the scanning head shown in FIG. 3 taken along the line X-X.

[Explanation of symbols]

10 Thermal print head board (scanning head) 2
0 Heat generating board 30 Circuit board 40 Paper sensor 70 Platen 100 Paper

Claims (2)

[Claims] 1. A scanning head that is attached to a support plate and pressed against a platen, and further comprising a sensor for detecting the presence or absence of paper located at a position facing the platen. 2. A sensor for detecting the presence or absence of paper in a scanning head that is attached to a support plate and pressed against a platen, together with a plurality of heating element driving elements provided corresponding to the heating elements on the scanning head. A scanning head characterized by mounting an element.