JP2019191009A - Structure of sensor of linear scale head - Google Patents

Abstract

To provide a structure of a sensor of a linear scale head which can be downsized.SOLUTION: A structure of a sensor of a linear scale head has a substrate 1, a light-sensitive chip 2, and a code pattern layer 3 forming a reticle pattern. The substrate 1 includes at least one conductive pad 11. The light-sensitive chip 2 is provided on the substrate 1 and has at least one pin 21. Each pin 21 is connected to one conductive pad 11 by a conductor 23. The code pattern layer 3 is formed on one surface of the substrate 1 which faces the light-sensitive chip 2 and is covered with a translucent insulating layer 4. A transparent protective layer 5 is formed on the insulating layer 4. A protective layer 5 is made of polyimide epoxy resin and covers each pin 21. Each pin 21 has an expansion part 22 extending from the protective layer 5. The conductor 23 connects the expansion part 22 and the conductive pad 11 to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a linear scale, and more particularly to a linear scale head sensor structure.

  The linear scale is an important device for measuring a minute distance in the field of precision machinery, and generally includes a measuring scale 6 (so-called main scale) and an optical head 7 as shown in FIG. . On the measuring scale 6, a code pattern (generally a reticle pattern) is provided. A vernier 71 and a photosensitive module 72 are provided inside the optical head 7. The vernier 71 is a glass block having a reticle pattern. When the optical head 7 and the measuring scale 6 are driven relatively, the reticle pattern on the measuring scale 6 and the vernier 71 is relatively displaced, and the continuous light intensity changes, and this is received and converted by the photosensitive module 72. The displacement distance was measured.

  However, in the conventional structure as described above, the vernier 71 is a three-dimensional structure occupying a fixed volume, and is separated from the photosensitive module 72 by the interval space 74 and connected by the connecting member 73. For this reason, the entire volume of the optical head 7 becomes large, and it has been difficult to satisfy the needs for downsizing the apparatus in the field of precision machinery.

  Furthermore, in the conventional structure, there are air molecules in the space 74 between the vernier 71 and the photosensitive module 72, and there are also floating particles such as dust and impurities, so refraction or diffraction occurs when light passes through. As a result, the measurement result may be adversely affected.

  An example of the above-mentioned reference document is Patent Document 1.

Taiwan Patent No. I447357

  The main object of the present invention is to form a reticle pattern directly on a photosensitive chip, and combine a vernier of a conventional structure and a photosensitive chip to reduce the volume of the linear scale head and reduce the size of the apparatus. It is to provide a sensor structure.

In order to solve the above problems, according to a first aspect of the present invention, there is provided a linear scale head sensor structure comprising a substrate, a photosensitive chip, and a code pattern layer for forming a reticle pattern, The substrate has at least one conductive pad, the photosensitive chip is provided on the substrate and has at least one pin, and each of the pins is connected to one conductive pad through a conductive wire, A sensor structure of a linear scale head is provided, wherein the code pattern layer is formed on one surface of the substrate facing the photosensitive chip and is covered with a light-transmitting insulating layer. .

  A transparent protective layer is formed on the insulating layer, and the protective layer is made of polyimide epoxy resin and covers each of the pins, and each of the pins has an extending portion extending from the protective layer, It is preferable that the extending portion and the conductive pad are connected by a conducting wire.

FIG. 1 is a sectional view showing a sensor structure of a linear scale head according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the pattern of the code pattern layer of the sensor structure of the linear scale head according to the embodiment of the present invention. FIG. 3 is a schematic diagram of a conventional structure.

  Please refer to FIG. As shown in FIG. 1, the sensor structure of a linear scale head according to an embodiment of the present invention includes a PCB substrate 1. On the substrate 1, at least one conductive pad 11 is provided. Conductive pads 11 are provided on both sides of the substrate 1 of the present embodiment.

  On the substrate 1, there is provided a photosensitive chip 2 that reads light in response to light and converts it into a signal. The photosensitive chip 2 is provided with at least one pin 21. In the present embodiment, pins 21 are provided on both sides of the photosensitive chip 2, and extending portions 22 extend from the pins 21 by a rewiring (RDL) process. Each extending portion 22 is connected to one conductive pad 11 via a conductive wire 23. A code pattern layer 3 that interacts with a linear scale measuring scale is formed on one surface of the opposite substrate 1 of the photosensitive chip 2, and only one pattern is printed on the photosensitive chip 2. Also good. The code pattern layer 3 of this embodiment is formed in a reticle pattern as shown in FIG.

  In addition, the photosensitive chip 2 has an insulating layer 4 that is translucent and covers the code pattern layer 3 for protection. Further, a transparent protective layer 5 made of polyimide epoxy resin is formed on the insulating layer 4. The protective layer 5 described above extends to cover each pin 21, but the extending portion 22 of each pin 21 extends from the protective layer 5 and is connected to the conductive pad 11 through the conductive wire 23.

  As can be seen from the above, the present invention has the code pattern layer 3 mounted directly on the photosensitive chip 2 and works in combination with the code pattern on the measuring scale to change the intensity of the transmitted light. The change can be measured by the photosensitive chip 2 to obtain the displacement distance. In the present invention, unlike the conventional structure in which the code pattern layer is attached to the structure of the glass block, the code pattern layer 3 is directly attached on the photosensitive chip 2, so that the structure is simplified and the entire volume of the apparatus is increased. Since it can be reduced, it is possible to meet the need for miniaturization of devices required in the field of precision machinery.

  Further, since the code pattern layer 3 is directly mounted on the photosensitive chip 2 and there is no space between them, the light transmitted through the code pattern layer 3 is received by the photosensitive chip 2. Therefore, the measurement result is more accurate without being affected by external factors such as air, dust, and impurities.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Photosensitive chip 3 Code pattern layer 4 Insulating layer 5 Protective layer 6 Measuring scale 7 Optical head 11 Conductive pad 21 Pin 22 Extending part 23 Conductive wire 71 Subscale 72 Photosensitive module 73 Connection member 74 Spacing space

Claims (2)

A linear scale head sensor chip structure comprising a substrate, a photosensitive chip, and a code pattern layer for forming a reticle pattern,
The substrate has at least one conductive pad;
The photosensitive chip is provided on the substrate and has at least one pin, and each of the pins is connected to one conductive pad via a conductor,
The sensor structure of a linear scale head, wherein the code pattern layer is formed on one surface of the substrate facing the photosensitive chip and is covered with a light-transmitting insulating layer. On the insulating layer, a transparent protective layer is formed,
The protective layer is made of polyimide epoxy resin and covers each pin.
Each of the pins has an extending portion extending from the protective layer,
2. The linear scale head sensor structure according to claim 1, wherein the extending portion and the conductive pad are connected by the conductive wire.