An absolute encoder for brightness positioning

Abstract

The present invention discloses an absolute encoder for brightness positioning, including a code mark and a multicolor light source, the code mark is provided with a gradient gray scale formed by bright and dark areas, the multicolor light source is opposite to a dichroic mirror, the transmission end of the dichroic mirror is opposite to the code mark, the code mark is opposite to a light intensity sensor, the reflection end of the dichroic mirror is opposite to the light intensity sensor, and a light on-off device is provided between the dichroic mirror and the light intensity sensor. The beneficial effects of the present invention are as follows: the specially designed code disk pattern realizes a continuous gray intensity distribution related to the absolute position only by a black and white two-color pattern, and realizes absolute positioning; the reflective light intensity detection is adopted, and the installation tolerance of the reading head is extremely wide, which is convenient for mass production of products; various types of light intensity sensors are convenient for high-speed data acquisition and processing; the light beam is separated and then recombined, and the front and rear light differences are used for positioning or trimming to compensate for the attenuation of the light source, thereby improving the position measurement accuracy.

Description

Technical Field

[0001] The invention relates to a displacement positioning mechanism, in particular to an absolute encoder for brightness positioning used for precise positioning of a long-stroke linear displacement mechanism. The invention is a low-cost implementation device for long-stroke precise positioning using a common light intensity sensor and a printed coding disc. Background Art

[0002] At present, absolute photoelectric encoders are mainly composed of multiple code channels, each of which is engraved with light and dark lines. The light and dark lines on all code channels together form a unique code value related to the position, which can be obtained by the photoelectric sensor to confirm the position.

[0003] However, the traditional absolute encoder principle has the following problems:

[0004] 1. It is difficult to produce multi-circle code channels. Expensive photolithography and coating equipment must be used and produced in a dust-free and clean environment. The product yield is low and the price is high.

[0005] 2. In order to improve the position resolution, it is mainly achieved by increasing the number of code channels and refining the engraved lines on each code channel, which makes the production complexity increase rapidly and the cost remains high.

[0006] 3. The finer the code line, the stronger the diffraction effect of light, which requires extremely high installation accuracy of the photoelectric sensor used to read position information. In addition, with the influence of factors such as mechanical wear of the encoder bearing, impact vibration, etc., the installation position of the photoelectric sensor will be slightly offset, causing the positioning signal to be distorted or even impossible to obtain, resulting in the failure of the encoder.

[0007] 4. For the absolute photoelectric encoder based on this principle, in order to reduce the difficulty of code disc production and photoelectric signal extraction while ensuring the position resolution, it is necessary to increase the diameter of the code disc, making it difficult to miniaturize and lighten this type of encoder.

[0008] 5. The encoder code disc of this principle is currently still mainly made of light-transmitting glass substrate or light-transmitting plastic substrate, which is difficult to apply to industrial and military application scenarios where impact, vibration and extreme temperature are common, limiting its commercialization and industrialization. Summary of the invention

[0009] The purpose of the present invention is to provide an absolute encoder for brightness positioning, which solves the problem of complex manufacturing and high cost of existing encoders. Therefore, the present invention proposes an absolute photoelectric encoder device with simple manufacturing, relatively high positioning accuracy and high cost performance. The code mark of this type of encoder can be made using ordinary printing equipment, and the reflected light intensity of the code disk is detected at high speed by a light intensity sensor to locate the absolute motion position.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] An absolute encoder for brightness positioning comprises a code mark and a multi-color light source. The code mark is provided with a gradient gray scale formed by bright and dark areas. The multi-color light source is opposite to a dichroic mirror. The transmission end of the dichroic mirror is opposite to the code mark. The code mark is opposite to a light intensity sensor. The reflection end of the dichroic mirror is opposite to the light intensity sensor. A light on-off device is provided between the dichroic mirror and the light intensity sensor.

[0012] The dichroic mirror separates the light beams of the multi-color light source, and the transmitted red and green light illuminate the code mark separately. The light intensity sensor is used to obtain the light intensity value Vrb, and then the reflected blue light is superimposed to obtain the light intensity value Vw. The difference Vw-Vrb can be used to measure the change in the luminous intensity of the light source. The red and green light intensity value Vrb can also be corrected based on this value to compensate for the attenuation of the light source, thereby improving the position measurement accuracy.

[0013] Furthermore, the code mark is a code band, the code channel of the code band is a rectangular area, and the code channel is divided into two areas by a diagonal line, one area is a dark area, and the other area is a light area. The diagonal line is divided, the dark area gradually increases from left to right, and the light area gradually decreases from left to right, forming a gradient grayscale, and each position corresponds to a grayscale value.

[0014] Furthermore, the code mark is a code disk, the code track of the code disk is a circular area, and the code track is divided into two areas by a dividing line, one area is a dark area, and the other area is a light area; the absolute angle value is a, and the distance between the corresponding dividing line and the center of the code disk is r, r=r0+a*(r1-r0) / 360°, where r0 is the inner circle radius of the code track, and r1 is the outer circle radius of the code track.

[0015] Furthermore, the dark area is a black area, and the light area is a white area. Black and white have opposite light absorption and reflection effects.

[0016] Furthermore, the code channel is printed on the code mark, which is simple and convenient to process.

[0017] Furthermore, a light homogenizing plate is provided between the code mark and the dichroic mirror.

[0018] Furthermore, a light homogenizing plate is provided between the code mark and the light intensity sensor.

[0019] Furthermore, a light homogenizer is provided between the dichroic mirror and the light intensity sensor.

[0020] Furthermore, the transmission end of the dichroic mirror is a red and green light transmission end, and the reflection end is a blue light reflection end, and the light intensity difference is calculated by utilizing whether the blue light is superimposed or not.

[0021] Furthermore, the multi-color light source is a white LED, which contains red, green and blue light.

[0022] Furthermore, the light-on / off device is a light-on / off liquid crystal device. Similarly, other devices can also be used to achieve the passage or shielding of the light beam.

[0023] Functions achieved by the present invention:

[0024] 1. The code disc can be printed in batches using ordinary printing equipment, and uniform color paper, plastic resin, metal, and glass can be used as printing substrates.

[0025] 2. Use only black and white to achieve gradient grayscale, with each grayscale value corresponding to a unique position.

[0026] 3. It can realize accurate real-time measurement of position under high-speed motion, and provide stable and reliable real-time position information for closed-loop motor control system.

[0027] 4. Use a dichroic mirror to separate the light, and then use the light difference before and after separation to determine the position or make adjustments.

[0028] Beneficial effects of the present invention:

[0029] 1. Use black and white to make the code disc on ordinary printing equipment.

[0030] 2. The specially designed code disc pattern achieves continuous grayscale light intensity distribution related to absolute position only by using black and white patterns, thus achieving absolute positioning.

[0031] 3. Adopting reflective light intensity detection, the permissible error of the reading head installation is extremely wide, which is convenient for mass production of products.

[0032] 4. All types of light intensity sensors facilitate high-speed data collection and processing.

[0033] 5. Separate the light beam and then recombine it, and use the front and rear light difference for positioning or trimming to compensate for the attenuation of the light source, thereby improving the accuracy of position measurement.

[0034] The aforementioned main scheme of the present invention and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the present invention; and in the present invention, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present invention, those skilled in the art can understand that there are many combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present invention, and they are not exhaustively listed here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the present invention.

[0036] Figure 2 It is a schematic diagram of the code band structure of the present invention.

[0037] Figure 3 It is a schematic diagram of the structure of the code disk of the present invention.

[0038] In the figure: 1-code mark, 2-light homogenizing plate, 3-dichroic mirror, 4-multicolor light source, 5-light on / off device, 7-light intensity sensor, 8-blue light, 9-red and green light. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific embodiments and drawings.

[0040] refer to Figure 1 As shown, an absolute encoder for brightness positioning includes a code mark 1, a light homogenizing plate 2, a dichroic mirror 3, a multicolor light source 4, a light on-off device 5 and a light intensity sensor 7.

[0041] The code mark 1 is a code strip (for linear displacement detection) or a code disc (for rotation angle detection). The code mark 1 is printed with a number of code tracks. The light and dark areas on the code track form a gradient grayscale. Specifically, the dark area is the black area, and the light area is the white area. The specific position of the code track has a specific gradient grayscale. The light reflection of the black and white areas of the code track is used to obtain the specific light intensity at the corresponding position.

[0042] refer to Figure 2 As shown, the code mark 1 is a code strip, and the code track is divided into two areas by a diagonal line (from lower left to upper right), the lower right area is a black area, and the upper left area is a white area. The diagonal division forms a black and white gradient bar code track.

[0043] refer to Figure 3 As shown, the code mark 1 is a code disk, and the code track of the code disk is a ring area. The code track is divided into two areas by a spiral dividing line. Specifically, the absolute angle value is a, and the distance between the corresponding dividing line and the center of the code disk is r, r=r0+a*(r1-r0) / 360°, where r0 is the inner circle radius of the code track, and r1 is the outer circle radius of the code track. The inner area is a black area, and the outer area is a white area. The spiral dividing line forms a black and white gradient ring code track.

[0044] The multicolor light source 4 is opposite to the dichroic mirror 3, the transmission end of the dichroic mirror 3 is opposite to the code mark 1, and the reflection end of the dichroic mirror 3 is opposite to the light intensity sensor 7. The multicolor light source 4 is a white LED, which includes three colors of blue, red and green. The dichroic mirror 3 separates the light beams of the multicolor light source 4, and the red and green lights 9 at the transmission end illuminate the code mark 1, and the blue light 8 at the reflection end illuminates the light intensity sensor 7.

[0045] The code mark 1 is opposite to the light intensity sensor 7, and a light-on / off device 5 is provided between the dichroic mirror 3 and the light intensity sensor 7. Preferably, the light-on / off device 5 is a light-on / off liquid crystal device. When powered on, the light-on / off device 5 is in a transparent state that allows light to pass through, and in a non-light-transmitting state that does not allow light to pass through when powered off.

[0046] A light homogenizing plate 2 is provided between the code mark 1 and the dichroic mirror 3, a light homogenizing plate 2 is provided between the code mark 1 and the light intensity sensor 7, and a light homogenizing plate 2 is provided between the dichroic mirror 3 and the light intensity sensor 7. The light homogenizing plate 2 is a professional optical diffraction sheet or frosted glass.

[0047] When the light-on / off device 5 is in the light-transmitting state, the totally reflected blue light is converted into scattered light by the light-diffusing plate 2 and enters the light intensity sensor 7. If the light-on / off device 5 is in the light-opaque state, the light intensity sensor 7 only receives the red and green light reflected from the code mark 1.

[0048] The working process of the present invention is as follows: when the reading head is stationary at a certain position, the light-on / off device is first kept in a non-light-transmitting state to obtain the red and green light intensity values ​​Vrb reflected by the code mark. Then the light-on / off device is turned on to a light-transmitting state to allow the blue light to diffusely reflect and the red and green light reflected by the code mark to enter the light intensity sensor. At this time, the measured value is Vw. The difference Vw-Vrb can be used to measure the change in the luminous intensity of the light source. The red and green light intensity values ​​Vrb can also be corrected based on this value to compensate for the attenuation of the light source, thereby improving the position measurement accuracy.

[0049] The above basic examples of the present invention and their further optional examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed for protection by the present invention. In the scheme of the present invention, each optional example can be arbitrarily combined with any other basic examples and optional examples.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An absolute encoder for brightness positioning, comprising a code mark (1) and a multi-color light source (4), characterized in that: The code mark (1) is provided with a gradient gray scale formed by bright and dark areas, the multicolor light source (4) is opposite to the dichroic mirror (3), the transmission end of the dichroic mirror (3) is opposite to the code mark (1), the code mark (1) is opposite to the light intensity sensor (7), the reflection end of the dichroic mirror (3) is opposite to the light intensity sensor (7), and a light on-off device (5) is provided between the dichroic mirror (3) and the light intensity sensor (7); When the reading head is stationary at a certain position, first keep the light-on / off device in a non-light-transmitting state to obtain the red and green light intensity values ​​Vrb reflected by the code mark; then turn on the light-on / off device to a light-transmitting state to allow the blue light to diffusely reflect and superimpose the red and green light reflected by the code mark to enter the light intensity sensor, at which point the measured value is Vw; the difference Vw-Vrb is used to measure the change in the luminous intensity of the light source, or to correct the red and green light intensity value Vrb based on the difference to compensate for the attenuation of the light source, thereby improving the accuracy of position measurement.

2. The absolute encoder for brightness positioning according to claim 1, characterized in that: The code mark (1) is a code band, the code track of the code band is a rectangular area, and the code track is divided into two areas by a diagonal line, one area is a dark area, and the other area is a light area.

3. The absolute encoder for brightness positioning according to claim 1, characterized in that: The code mark (1) is a code disk, the code track of the code disk is a ring-shaped area, and the code track is divided into two areas by a dividing line, one area is a dark area, and the other area is a light area; The absolute angle value is a, and the distance between the corresponding dividing line and the center of the code disk is r, r=r0+a*(r1-r0) / 360°, where r0 is the inner circle radius of the code channel and r1 is the outer circle radius of the code channel.

4. The absolute encoder for brightness positioning according to claim 2 or 3, characterized in that: The dark area is a black area, the light area is a white area, and the code channel is printed on the code mark (1).

5. The absolute encoder for brightness positioning according to claim 1, characterized in that: A light homogenizing plate (2) is provided between the code mark (1) and the dichroic mirror (3).

6. The absolute encoder for brightness positioning according to claim 1, characterized in that: A light homogenizing plate (2) is provided between the code mark (1) and the light intensity sensor (7).

7. The absolute encoder for brightness positioning according to claim 1, characterized in that: A light homogenizing plate (2) is provided between the dichroic mirror (3) and the light intensity sensor (7).

8. The absolute encoder for brightness positioning according to claim 1, characterized in that: The transmission end of the dichroic mirror (3) is a red and green light transmission end, and the reflection end is a blue light reflection end.

9. The absolute encoder for brightness positioning according to claim 1 or 8, characterized in that: The multi-color light source (4) is a white LED.

10. The absolute encoder for brightness positioning according to claim 1, characterized in that: The light-on / off device (5) is a light-on / off liquid crystal device.

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