Constant temperature bath

Abstract

To provide a calibration device which enables suppression of dew condensation or freezing of a glass surface of a laser irradiation port of an optical distance measuring device even when a thermostatic chamber is set to be low temperature, and which consequently enables accurate calibration.SOLUTION: A calibration device 1 for an optical distance measuring device is provided, comprising a thermostatic chamber 2 which has a housing portion 3 housing an optical distance measuring device 4, and which can keep temperature in the housing portion 3 constant, wherein a part of the housing portion 3 is covered with a shielding member 32 having a light projection hole 34 communicating with the outside, and an air blower 5 capable of blowing air toward the outside of the housing portion 3 is provided around the peripheral edge of the light projection hole 34, without blocking a course of laser light L emitted from the optical distance measuring device 4 housed in the housing portion 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the calibration of optical distance measuring devices. Thermostatic bath used for It is related to. [Background technology]

[0002] As described in Patent Document 1, an optical distance measuring device is known that measures the distance to an object based on the time it takes for a projected laser beam to hit the object, reflect, and return. Patent Document 1 describes a distance measuring device in which the distance to the object calculated based on the time is corrected by distance correction value data corresponding to the temperature inside the device in order to eliminate errors caused by temperature changes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 6-72074

[0004] The inventors developed a calibration device equipped with a thermostatic chamber capable of housing an optical distance measuring device as a means of acquiring correction data for correcting errors in calculated values due to temperature changes. During calibration tests, a laser beam is projected from the optical distance measuring device inside the thermostatic chamber toward a measurement object outside the chamber. However, the door of the thermostatic chamber must be left open to avoid obstructing the path of the laser beam, making it difficult to control the temperature inside the thermostatic chamber. Therefore, the inventors equipped the thermostatic chamber with an outer door and an inner door with a projection hole through which the laser beam can pass, and installed the optical distance measuring device behind the inner door, resulting in a calibration device that is easy to control the temperature.

[0005] However, when the inside of the thermostatic chamber is kept in a low-temperature environment such as -30°C and the outer door is left open, outside air at room temperature enters the area around the optical distance measuring device through the light projection hole in the inner door, causing condensation or freezing on the glass surface provided at the laser irradiation port of the optical distance measuring device, making it difficult to accurately adjust the light intensity.One possible method to prevent condensation or freezing on the glass surface is to cover the light projection hole with a translucent material such as glass, but in that case there is a risk that accurate light intensity adjustment will not be possible due to a decrease in transmittance or diffuse reflection of returned light. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the object of the present invention is to solve the above-mentioned conventional problems and provide a calibration device that can prevent condensation or freezing on the glass surface of the laser irradiation port of an optical distance measuring device even when the temperature inside the thermostatic chamber is low, thereby enabling accurate calibration. [Means for solving the problem]

[0007] To solve the above problems ,light Calibration of optical distance measuring devices Thermostatic bath used for And, the thermostatic bath has a housing portion for housing the optical distance measurement device and is capable of maintaining a constant temperature inside the housing portion; of the storage portion On the inner door A light projection hole is formed that connects to the outside. And, On the periphery of the light projection hole, The aforementioned Without obstructing the path of the laser light emitted from the optical distance measuring device housed in the housing part, From the edge of the light hole It is characterized by being equipped with a blower capable of blowing air to the outside. Constant temperature bath Let's say.

[0008] Furthermore, it is preferable that the blower comprises an intake section equipped with a fan that generates wind, and a cylindrical tubular section with open ends at the tip and base ends, the tubular section having a hollow passage between its outer and inner walls that receives the wind generated by the intake section, and a slit formed in the inner wall that discharges the wind. [Effects of the Invention]

[0009] The present invention makes it possible to provide a calibration device that can prevent condensation or freezing on the glass surface of the laser irradiation port of an optical distance measuring device even in low-temperature environments, thereby enabling accurate calibration. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a calibration device according to an embodiment and a target installed on the front side of the calibration device. FIG. [Figure 2] FIG. 2 is a cross-sectional view of the calibration device and target of FIG. 1. [Figure 3] 1 is a perspective view of a housing unit according to an embodiment, showing a state in which a blower is not attached to a light projection hole. [Figure 4] FIG. 2 is a front view of the storage unit according to the embodiment. [Figure 5] 5 is a cross-sectional view taken along the line AA in FIG. 4. [Figure 6] 6 is a partially enlarged view of FIG. 5. The arrows indicate the air flow when the temperature inside the container is set to a temperature lower than the temperature outside the thermostatic chamber. [Figure 7] FIG. 1 is a perspective view of a blower according to an embodiment. [Figure 8] FIG. 2 is a front view of the blower according to the embodiment. [Figure 9] This is a cross-sectional view taken along the line AA in Fig. 8. However, the arrows indicate the air flow when the temperature inside the container is set lower than the temperature outside the thermostatic chamber. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the invention will be described below. As shown in FIGS. 1 and 2, a calibration device 1 of this embodiment has a storage section 3 that stores an optical distance measurement device 4, and is equipped with a thermostatic chamber 2 that can maintain the interior of the storage section 3 at a predetermined temperature condition using temperature control means. The thermostatic chamber 2 of this embodiment has an opening 21 provided on the front surface and an outer door 22 that can cover the entire surface of the opening 21, and the storage section 3 is a box-shaped recess formed in the depth direction from the opening 21. A portion of the storage section 3 is covered by a shielding member 32 that has a light-projecting hole 34 that communicates with the outside. The shielding member 32 of this embodiment is provided on the front side of the optical distance measurement device 4 stored in the storage section 3 so as to cover the cross section of the storage section 3.

[0012] A plate-shaped target 9, which is the object to be measured, is provided on the front side of the calibration device 1, facing the opening 21. In this embodiment, the target 9 is placed at a position a distance D away from the optical distance measurement device 4 housed in the housing section 3 so that the laser light L emitted from the optical distance measurement device 4 hits the target 9 perpendicularly. Note that this distance D can be any value.

[0013] The optical distance measurement device 4 of the embodiment can calculate the distance to the measurement object from the time it takes for the projected laser light L to travel to and from the measurement object. When performing a calibration test in the embodiment, the optical distance measurement device 4 is housed in the housing 3, the housing 3 is controlled to a predetermined temperature, the outer door 22 of the thermostatic chamber 2 is opened, the optical distance measurement device 4 emits laser light L toward the target 9, and the distance to the target 9 is calculated based on the time it takes for the laser light L reflected from the target 9 to be received. In this embodiment, assuming that the optical distance measurement device 4 will be used outdoors, the internal temperature of the housing 3 is controlled within a range from sub-zero ambient temperature to extremely hot ambient temperature. The optical distance measurement device 4 is adjusted so that the distance to the target 9 calculated by the optical distance measurement device 4 falls within a predetermined range in each temperature range.

[0014] Here, the storage unit 3 will be described. As shown in FIG. 2, the storage unit 3 of this embodiment has a rear space shielded by a shielding member 32. The area behind the shielding member 32 is an installation space 35 in which an optical distance measurement device 4 is installed. As shown in FIGS. 3 and 4, an installation stand 31 capable of accommodating multiple optical distance measurement devices 4 may be provided in the installation space 35. The installation stand 31 of this embodiment has two rows of compartments in the left-right direction and four rows in the up-down direction, and each compartment can accommodate up to three optical distance measurement devices 4, making it possible to inspect and calibrate multiple devices at once. The optical distance measurement device 4 is installed in the installation stand 31 so that the laser irradiation port 41 that emits laser light faces the front side.

[0015] In the embodiment, the inner door 322 provided on the front surface of the installation stand 31 and the shielding plates 321 covering the top and bottom of the inner door 322 function as the shielding member 32. In the embodiment, a total of eight inner doors 322 are provided, one for each compartment of the installation stand 31, and the inner doors 322 can be opened and closed for each compartment. A handle 33 is attached to each inner door 322. Since the cross section of the accommodation section 3 is covered by these shielding members 32, temperature fluctuations are suppressed in the installation space 35 behind the shielding members 32 even when the outer door 22 of the thermostatic chamber 2 is open, and it becomes possible to maintain the optical distance measurement device 4 at a predetermined temperature.

[0016] The inner door 322 has a light projection hole 34 formed therein, which connects the inside and outside of the installation space 35. Laser light L emitted from the optical distance measurement device 4 installed on the installation stand 31 passes through this light projection hole 34 and travels toward the target 9. By forming the light projection hole 34 in the inner door 322, it is possible to project the laser light L from the inside of the storage section 3 toward the outside without opening the inner door 322, thereby improving the airtightness of the installation space 35. Furthermore, it is preferable to configure the light projection hole 34 so that it is closed when not in use and opened when in use, as this further improves the airtightness of the installation space 35 and suppresses temperature fluctuations.

[0017] In this embodiment, as shown in FIGS. 4 to 6, a blower 5 is provided around the periphery of the light-projecting hole 34. As will be described in detail later, the blower 5 in this embodiment is attached to the inner door 322 and can create an air flow from the inside to the outside of the installation space 35. Although FIGS. 4 to 6 show a state in which one blower 5 is provided, any number of blowers 5 may be provided as needed depending on the set temperature of the installation space 35 and the number of optical distance measurement devices 4 to be installed. FIG. 6 also shows the air flow when the temperature of the accommodation section 3 is set to a temperature lower than the temperature outside the thermostatic chamber 2, with and without the blower 5 provided.

[0018] 6, in the upper compartment where the inner door 322 is not provided with the blower 5, part of the cool air C1 in the installation space 35 flows out through the light projection hole 34, and outside air OA1, which is hotter than the cool air C1, flows into the installation space 35. At this time, condensation, frost, or freezing may occur on the glass surface (not shown) provided at the laser irradiation port 41 of the optical distance measurement device 4. If condensation or the like occurs on the glass surface, the transparency of the glass surface decreases, making it difficult to perform accurate calibration.

[0019] On the other hand, when the blower 5 is provided at a position corresponding to the light projection hole 34, as in the lower section shown in Fig. 6, the blower 5 forms an air flow F2 that flows from the inside to the outside of the installation space 35. This prevents outside air OA2, which is hotter than the cool air C2 in the installation space 35, from flowing into the installation space 35. This makes it possible to prevent condensation, frost, or freezing from occurring on the glass surface provided at the laser irradiation port 41 of the optical distance measurement device 4. Note that the blower 5 of the embodiment is attached at the periphery of the light projection hole 34 so as not to block the opening of the light projection hole 34, and therefore does not obstruct the path of the laser light L passing through the light projection hole 34.

[0020] Here, blower 5 will be described. As shown in FIGS. 7 to 9, blower 5 of the embodiment includes intake section 51 having fan 511 therein for generating airflow, and tubular section 52 having a distal end opening 531 at the distal end and a proximal end opening 532 at the proximal end, with space 53 formed between both openings 531, 532. In the present embodiment, tubular section 52 has a cylindrical shape, but is not limited thereto and may have other shapes such as a rectangle. Tube section 52 is connected to intake section 51, and air generated by intake section 51 can be introduced into tubular section 52.

[0021] As shown in Fig. 9, the tubular portion 5 is formed in a cylindrical shape by a hollow wall made up of an outer wall 521 and an inner wall 522, and a hollow passage 523 that receives the air generated by the intake portion 51 is formed between the outer wall 521 and the inner wall 522. In addition, the inner wall 522 is formed with a slit 54 that serves as an outlet for discharging the air that has flowed from the intake portion 51 into the hollow passage 523 into the space portion 53 inside the tubular portion 52. It is preferable that the slit 54 is formed continuously over almost the entire circumference of the inner wall of the tubular portion 52. As shown in Fig. 9, the slit 54 in the embodiment is formed at the base end side opening 53 of the inner wall 522. 2 The narrow gap is provided between the inner wall 522 and the outer wall 521, the end of which is formed in a U-shaped cross section, so as to form a ring at a position close to the opening 531, and the end of the outer wall 521 guides the airflow so that it blows out toward the tip opening 531.

[0022] In blower 5 having the above-described structure, when fan 511 in intake section 51 is activated, intake air F1, which is a flow of air drawn into blower 5, is generated, as shown in Fig. 9. Intake air F1 flows into hollow passage 523 of tubular section 52 and is discharged into space 53 through narrow slit 54. At this time, intake air F1 discharged from slit 54 toward tip-end opening 531 has a high wind speed, and therefore a strong air flow F2 is generated in space 53 toward tip-end opening 531.

[0023] The blower 5 is attached to the periphery of the light projection hole 34 at a position where the laser light L passing through the light projection hole 34 can pass through the space 53. In this case, the space 53 preferably has an inner diameter larger than the path of the laser light L so as not to obstruct the path of the laser light L, and is disposed at a position where it does not interfere with the path of the laser light L. Note that the blower 5 of the embodiment is formed so that the inner diameter of the space 53 is larger than the inner diameter of the light projection hole 34, and is disposed on the front side of the inner door 322 at a position where the central axis of the space 53 and the central axis of the light projection hole 34 substantially coincide.

[0024] Furthermore, since the blower 5 is disposed so that the tip-end opening 531 faces the target 9 and the base-end opening 532 faces the optical distance measurement device 4 housed in the installation space 35, when the blower 5 is operating, an air flow is formed from the inside to the outside of the installation space 35 as shown in Fig. 9. This increases the force with which the cool air C2 inside the installation space 35 is blown out of the installation space 35, making it possible to prevent the warm outside air OA2 from entering the installation space 35.

[0025] In this way, the present invention can provide a calibration device 1 that can prevent condensation or freezing on the glass surface of the laser irradiation port 41 of the optical distance measuring device 4 even in a low-temperature environment, thereby enabling accurate calibration.

[0026] Although the present invention has been described above by taking the embodiments as examples, the present invention is not limited to the above-described embodiments and can be embodied in various forms. [Explanation of symbols]

[0027] 1 Calibration equipment 2 Constant temperature bath 21 Opening 22 Outer door 3. Storage section 31 Installation stand 32 Shielding member 321 Shielding plate 322 Inner door 33 Handle 34 Light source 35 Installation space 4 Optical distance measuring device 41 Laser emission port 5. Blower 51 Intake section 511 Fan 52 Cylinder part 53 Space part 531 Tip side opening 532 Proximal opening 54 Slit 9 Target D distance L laser light C1, C2 cold air OA1, OA2 Outside air F1: Intake F2: Air flow

Claims

1. A thermostatic oven used for calibrating an optical distance measuring device, comprising: The thermostatic bath is a housing portion for housing the optical distance measuring device; The temperature inside the storage section can be kept constant, A light projection hole communicating with the outside is formed in the inner door of the storage section, A thermostatic bath characterized in that a fan is provided around the periphery of the light projection hole, capable of blowing air from the periphery of the light projection hole to the outside without obstructing the path of the laser light emitted from the optical distance measuring device housed in the housing section.

2. The blower is an intake section equipped with a fan that generates wind; a cylindrical portion having open distal and proximal ends, 2. The thermostatic oven according to claim 1, wherein the cylindrical portion has a hollow passage between an outer wall and an inner wall for receiving the air generated by the air intake portion, and a slit is formed in the inner wall for discharging the air.

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