JP2688322B2 - Reflective telescope with air flow control device in lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art When installing a medium or large reflection telescope of 40 cm to 150 cm class for astronomical observation, it is desirable to place it in a place where there is little influence of dust, town lights, etc., which causes unclear image formation and deterioration of contrast. Therefore, it is generally installed in the suburbs such as in the mountains, avoiding urban areas. However, traffic in such a place is inconvenient, and it may be dangerous to move to the place even in winter, for example, and in some cases, traffic may become impossible and observation itself may not be possible. Therefore, it is the current situation that it is difficult for the general public to easily observe. Under these circumstances, recently, it has been considered to install an observatory for public observation in a place where transportation is good and general people can easily gather, such as the center of an urban area. In such a case, the blocking of dust and town lights is mainly performed by the lens barrel.

That is, the lens barrel has a role as an outer shell for accommodating and supporting the main reflecting mirror and the sub-reflecting mirror inside, and protecting the reflecting mirror inside these from the outside. For this reason, the outer wall of the lens barrel is always exposed to the outside air, and is warmed by the outside air during the day and cooled at night. This causes a temperature difference between the warm air inside the lens barrel and the cold air outside the lens barrel, especially when used at night.
This temperature difference causes an air flow in the lens barrel. Then, the airflow in the lens barrel becomes an upward airflow that flows upward with a predetermined strength, and the fluctuation of the upward airflow affects the optical path and causes the image to be blurred.

In order to prevent such a problem, normally, an in-mirror fan and a ventilation hole for controlling an air flow in the lens barrel are provided at a predetermined portion of the lens barrel, and the rotation of the in-mirror fan causes hot air and air flow in the lens barrel. Is forcibly discharged to the outside to suppress fluctuations due to updrafts.

[0004]

However, since the rotation of the fan in the mirror as described above also causes vibrations at the same time, in some cases, the vibrations are transmitted to the lens barrel, the main reflecting mirror and the sub-reflecting mirror, and the like. Often causes blurring.
In particular, there is a problem that as the magnification increases, the blurring of the image increases, making it difficult to obtain a clear image. Therefore, a measure for suppressing such vibration as much as possible has been desired.

The present invention has been made by paying attention to such a conventional technique. In the lens barrel, the vibration of the fan in the mirror can be minimized while the airflow in the lens barrel is sufficiently discharged. An object is to provide a reflecting telescope having an air flow control device.

[0006]

As a result of earnest research to solve the above-mentioned problems, the inventor has said that the strength of the ascending airflow in the lens barrel changes depending on the inclination of the lens barrel. The facts have been found, and the present invention has been completed based on this finding.

That is, the ascending airflow in the lens barrel has the strongest airflow when the lens barrel is vertical, and the airflow gradually weakens as the lens barrel tilts. Therefore, if the rotation speed of the in-mirror fan is changed according to the strength of the air flow in the lens barrel, it is possible to suppress the vibration accompanying the rotation of the fan in the mirror while discharging the air flow in the lens barrel. become.

Specifically, the present invention relates to a reflection telescope having an in-mirror fan for controlling the air flow in the lens barrel, a tilt for detecting the tilt angle of the lens barrel and generating a detection signal corresponding to this tilt angle. The reflection telescope includes an angle detection means and an in-mirror fan rotation speed control means for controlling the rotation speed of the in-mirror fan based on the detection signal.

[0009]

The air flow control device in the lens barrel according to the present invention comprises the tilt angle detection means and the fan rotation speed control means in the mirror. Since the tilt angle detecting means detects the tilt of the lens barrel as an electric signal each time, the strength of the air flow in the lens barrel can always be easily grasped. Upon receiving this detection signal, the in-mirror fan rotation speed control means increases the rotation speed of the in-mirror fan in response to this when the lens barrel is vertical and the ascending air current is rising with the strongest force. When the ascending flow is gradually weakening and the flow of the ascending air current becomes weaker, the rotation speed of the mirror fan is also gradually decreased.

As a result, unnecessary rotation of the in-mirror fan is omitted, and a rotation speed necessary and sufficient for discharging the air current in the lens barrel is always maintained. That is, the fluctuation of the ascending air current is sufficiently suppressed, while the vibration of the lens barrel is also suppressed to a low level, and a clear image can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to FIGS.
It will be described based on. In addition, the same reference numerals are given to portions common to the related art, and overlapping description will be omitted.

As shown in FIG. 1, a reflecting telescope 1 equipped with an in-lens-barrel airflow control device according to this embodiment is provided in a barrel 2.
The main reflecting mirror 3 and the sub-reflecting mirror 4 are housed and supported in a state of facing each other. The light R from the celestial body strikes the main reflecting mirror 3 to become reflected light R ₁ , and the reflected light R ₁ is further reflected by the sub-reflecting mirror 4 to become reflected light R ₂ . The reflected light R ₂ passes through the central hole 5 of the main reflecting mirror 3 and reaches the eyepiece 6. Main reflector 3
An in-mirror fan 7 is provided on the inner wall of the rear of the lens barrel so that hot air in the mirror and air flow 9 in the lens barrel are discharged to the outside of the lens barrel through a ventilation hole 8.

The equatorial mount 10 is for pivotally supporting the lens barrel 2 and for displacing the direction and position of the lens barrel 2 for capturing an object to be viewed. The equatorial mount 10 has a servo mechanism including an encoder (not shown) as "tilt angle detecting means" and a control circuit (not shown) as "in-mirror fan rotation speed control means" and a servo motor for rotating the in-mirror fan. Is provided.

When the tilt of the lens barrel is vertical, as shown in FIG. 2, the air current 9 in the lens barrel warmed by the main reflecting mirror 3 and the inner wall of the lens barrel 2 becomes an ascending air flow A in the vertical direction. To rise. At this time, the ascending airflow A in the lens barrel flows in the vertical direction with the maximum momentum due to the enthusiast effect. In such a case, the mirror fan 7 is rotated to the maximum as in the conventional case. That is, the encoder detects this inclination (vertical) and transmits it to the servomechanism, and the servomechanism that receives this detection signal causes the exhaust airflow A ₁ + A ₂ to be slightly stronger than the ascending airflow A in that flow, inside the mirror. Rotate the fan 7 faster.

FIG. 3 is an example showing a state in which the lens barrel 2 is tilted at a tilt angle θ. In this way, the inclination θ
As shown in FIG. 4, it becomes difficult for the updraft B to rise vertically directly in the mirror, and the updraft A becomes weaker than the updraft A in FIG. 1 as shown in FIG. Therefore, in such a case, the airflow in the lens barrel 2 can be sufficiently discharged even if the fan 7 in the mirror is slower than that in the vertical state in the previous period. That is, when the lens barrel 2 is tilted, the encoder transmits a detection signal corresponding to this tilt to the servo mechanism, and the servo mechanism mirrors the exhaust airflow B ₁ + B ₂ to a level slightly stronger than the ascending airflow B in the flow. The inner fan 7 is controlled to a low rotation speed. By doing so, it is possible to suppress the occurrence of vibrations by the in-mirror fan 7 as much as possible while surely discharging the air flow in the lens barrel 2.

When the lens barrel is placed almost horizontally, the upward airflow B can hardly rise in the vertical direction and the flow becomes extremely weak. Therefore, the rotation speed of the in-mirror fan 7 is further reduced. can do. When the lens barrel faces downward, the flow of the updraft B stops.

As the "tilt angle detecting means", a potentiometer, a differential transformer or the like can be adopted in addition to the encoder.
As the "in-mirror fan rotation speed control means", an electronic governor type motor or the like can be adopted.

[0018]

The reflecting telescope having the air flow control device in the lens barrel according to the present invention has the contents as described above, and the lens barrel is provided by the tilt angle detection means and the fan rotation control means in the mirror. Is detected and the rotation of the fan inside the mirror is controlled based on this detection signal, the airflow inside the lens barrel can be reliably discharged and the vibration of the lens barrel due to the fan inside the lens barrel is suppressed as much as possible. You can Therefore, a clear image can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a lens barrel of a reflecting telescope according to an embodiment of the present invention is vertical.

FIG. 2 is a cross-sectional view showing a state of air flow in the lens barrel when the lens barrel is vertical.

FIG. 3 is a cross-sectional view showing a state in which the lens barrel of the reflecting telescope according to the embodiment of the present invention is tilted.

FIG. 4 is a cross-sectional view showing a state of airflow in the lens barrel when the lens barrel is tilted.

[Explanation of symbols]

1 Reflective Telescope 2 Lens Tube 3 Main Reflector 4 Sub-Reflector 5 Central Hole 6 Eyepiece 7 Fan in the Mirror 8 Ventilation Hole 9 Airflow inside the Mirror θ Incline Angle A Ascending Airflow A ₁ , A ₂ Exhaust Airflow B Ascending Airflow B ₁ , B ₂ exhaust air flow

Claims (1)

(57) [Claims] 1. A reflection telescope having an in-mirror fan for controlling the air flow in the lens barrel in a lens barrel, comprising tilt angle detecting means for detecting a tilt angle of the lens barrel and generating a detection signal corresponding to the tilt angle. A reflection telescope, comprising: an in-mirror air flow controller having an in-mirror fan rotation speed control means for controlling the rotation speed of the in-mirror fan based on the detection signal.