JPS6037449B2 - zoom lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom lens that can limit the zooming range.

In recent years, there has been an increasing demand for zoom lenses for TV (Television) with high zoom ratios, and in response to this demand, development of zoom lenses with high zoom ratios is progressing.

However, due to constraints in lens production, it is difficult to supply zoom lenses with a large aperture, and as shown in Figure 1, the maximum aperture F value is This has the disadvantage that the results are depressed. Furthermore, when using a zoom lens with such a high zoom ratio, it is not always necessary to fully utilize the zoom function of the zoom lens, and in particular, the telephoto side is used less frequently than the wide side. Taking into account the size of the subject and the distance to the subject, for example, even if a zoom lens has a high zoom ratio of 3, it is limited to a zoom ratio of 2 kan, and if the zoom ratio exceeds 2 kan. This is because it is used while taking care not to give an unnatural feeling to the image due to zooming within the range. Based on the above, a zoom lens with a high zoom ratio can be used as described below. In other words, the first usage mode is to fully utilize the zoom function of the zoom lens by ignoring the drop in the maximum aperture F value in the high zoom ratio region, and the second usage mode is to fully utilize the zoom function of the zoom lens. The third usage mode is to avoid zooming into areas where the aperture F value drops, and even if it is within the range where the open aperture F value can be kept constant, the range is further restricted to prevent excessive zooming. In addition, the fourth usage mode is to ignore the slight drop in the open aperture F value and extend the limited range according to the third usage mode to the area where the open aperture F number drops. Conceivable.

Here, there is no problem in the case of the first mode of use, but in the case of the second mode of use, means for preventing zooming to an area where the open aperture F number drops, and third and fourth modes are required. In the case of the usage mode, it can be said that it is desirable for operation during zooming to have a means for preventing excessive zooming. It is desirable that at least the former is configured to be linked to means for adjusting the aperture mechanism depending on the brightness of the subject and setting the aperture value in accordance with the brightness of the subject. In other words, as shown in Fig. 1, for example, in the case of an open aperture F value (F; 1.6), the F
Since the value drops, it is possible to zoom to a zoom ratio of 23 tones, and if the aperture F value is set to (F; 3.2), the aperture F value of (F; 3.2) can be maintained. This is because the range in which the aperture F-number can be kept constant changes correspondingly depending on the value of the aperture F-number so as to enable zooming up to a double zoom ratio. However, configuring the means for preventing zooming to an area where the aperture value drops in this way to be linked to the aperture value setting means is a second mode of use, that is, to prevent zooming to an area where the aperture value falls. Although it is suitable for use in non-conventional situations, it causes inconvenience when used in other ways. Therefore, in view of the above, the present invention provides a zoom lens that is capable of being used in the above-mentioned manner and that eliminates all of the above-mentioned drawbacks and difficulties. Hereinafter, one embodiment of a zoom lens according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a partially sectional side view showing the main parts of an embodiment of the zoom lens according to the present invention, and FIG. 3 is a sectional view taken along the line X--X in FIG. 2.

In FIGS. 2 and 3, reference numeral 10 indicates a zoom lens mirror 10, which, as is well known, is equipped with a focus mechanism, a zoom mechanism, an aperture mechanism, and the like. That is, the focus mechanism section includes a focus lens holding frame 12 disposed in a fixed cylinder 11, and an interlocking pin 12a set on the outer periphery of this lens holding frame 12.
A straight keyway hole 11a in the direction along the optical axis formed in the side wall of the
The focusing cam barrel 13 is engaged with the spiral cam slot 13a of the focusing cam barrel 13, which is rotatably mounted on the outer periphery of the fixed barrel 11, and is moved forward and backward along the optical axis by rotating the cam barrel 13. It is configured. The zoom mechanism section also includes a lens holding frame 14 which is arranged in the fixed barrel 11 and holds a part of the lens group of the zoom lens system.
A zoom cam barrel 1 is rotatably mounted on the outer periphery of the fixed barrel 11 through a linear keyway hole 11b extending along the optical axis formed in the side wall of the fixed barrel 11 with an interlocking pin 15 fixed on the outer periphery.
The cam cylinder 16 is engaged with the spiral cam slot 16a of No. 6, and is configured to move forward and backward along the optical axis by rotating the cam cylinder 16. Furthermore, as shown in FIG. 4, the aperture mechanism section includes a plurality of aperture blades 17 (one blade is shown as a representative in FIG. 4) having a rotating shaft on the flange portion 11c of the fixed cylinder 11. and an aperture ring 18 having a long groove hole 18a that mates with the drive pin 17a of the aperture blade 17,
This is a so-called iris diaphragm configured so that the diaphragm blades 17 are moved in and out of the optical path to narrow down the optical path by applying a rotation angle to the diaphragm ring 18 by external operation. and,
Reference numeral 20 shown in FIG. 2 indicates a zoom/focus operation section, and this operation section 20 is supported by a support machine frame 21 that is fixedly supported by the fixed joint 11.
1, a rotary cylinder 22 rotatably supported parallel to the optical axis, an operating rod 23 which is iron-fitted within the rotary cylinder 22 so as to be push-pull operable and extends to the hand; A sliding body 25 is equipped with iron on the outer periphery and connected to the operating lever 23 with a connecting pin 24 through a linear keyway hole 22a formed in the longitudinal direction of the rotary cylinder body 22, and a drum is rotatably mounted on the sliding body 25. It consists of a rotary body 26 and a driving gear 27 fixedly mounted on the rotary cylinder body 22.

The zoom/focus operation unit 20 and the zoom mechanism unit described above are connected to a wire fixed to the rotating body 26, and both ends of which are wound around the cam barrel 16 in opposite directions. 30', and as the rotating body 26 moves in the left-right direction in FIG. 2 integrally with the operating rod 23, the wire 30
One end of the cam cylinder 16 is pulled to rotate the cam cylinder 16. Note that in FIG. 2, the reference numeral 31 indicates a guide roller. Further, the zoom/focus operation section 20 and the aforementioned focus mechanism section are connected to the drive gear 27 and the focus mechanism section.
The toothed portion 13b formed along the outer periphery of the waste cam cylinder 13 is meshed and connected via a gear train consisting of gears 32, 33, and 34, and the rotating cylinder 22 is connected to the connecting pin 24 and the linear keyway hole 22a. Since the cam cylinder 13 is rotated integrally with the operating rod 23 due to the above-mentioned relationship, the cam cylinder 13 is rotated by rotating the operating rod 23 using the gear configuration described above. Note that during zooming by pushing and pulling the operating rod 23, the rotating cylinder 22 does not rotate.
It does not affect focusing in any way, and when focusing by rotating the operating rod 23, the rotating body 2
6 does not rotate and does not affect the zoom in any way.

Therefore, in the zoom lens applied to this embodiment, the operating rod 2
Zooming is performed by pushing and pulling 3, and focusing is performed by rotating the operating rod 23. Zoom lenses having such a configuration are well known and will not be described in more detail.

Next, to explain a zoom lens in which the structure according to the present invention is added to the above structure, in this embodiment, when the zoom cam barrel 13 is rotated counterclockwise in FIG. , wide zooming, and telezooming when rotated clockwise.

The configuration added to this embodiment is that the zoom range adjustment knob 40 and a zoom operation amount adjustment section that adjusts the zoom operation amount in conjunction with the adjustment knob 40, as described later, are similarly linked. It consists of a zoom operation amount adjustment section that adjusts the zoom operation amount, and a control device that automatically controls the adjustment knob 40 based on aperture value information.

To explain these in more detail, first, the zoom operation amount adjusting section enters a bearing section 41 mounted on a fixed machine frame 21 and rotatably supporting one end of the rotary cylinder body 22 when rotating counterclockwise. The rotating cylinder body 22 is screwed with iron so that the tip thereof is
It has a ball stopper member 42 extending therein.

This shaft-like stopper material 42 has a gear 44 that meshes with a wide main gear 43 arranged to rotate physically with the zoom range adjustment knob 40, and rotates the adjustment knob 40. The position of the tip of the operating rod 23 is determined by the threaded relationship with the bearing member 41, and the amount of push operation corresponding to telezooming of the operating rod 23 is regulated. has been done. Next, as shown in FIG. 3, the zoom operation amount adjusting section
Fixed machine frame 2 formed to surround a part of the outer periphery of 6
A stopper member 45 is provided on the outer circumference of the semi-cylindrical machine frame 21a, which is a part of the machine frame 1, so as to be movable so as to rotate in the circumferential direction with respect to the light koji. This stopper member 45
faces into the rotation path of the stopper receiving portion 16b provided on the outer periphery of the cam cylinder 16 through a long hole 21b formed in the semi-cylindrical machine frame 21a on its inner periphery, and prevents clockwise rotation of the cam cylinder 16. It has a stopper part 45a that sometimes engages with the stopper receiving part 16b to prevent further rotation, and an idler gear 46 that meshes with the main gear 43 on the outer periphery.
The stopper receiving portion 16b' of the cam cylinder 16 of the stopper portion 45a moves in the circumferential direction with respect to the optical axis when the adjustment operation knob 40 is rotated. The position relative to the object is determined. Note that the part indicated by the reference numeral 21c provided on the inner circumferential wall of the machine frame 21a abuts against the stopper receiving portion 16b of the cam barrel 16, and prevents the cam barrel 16 from rotating in the counterclockwise direction. It is a stopper that determines the Furthermore, the control device, that is, the device that automatically controls the adjustment knob 40 using aperture value information, includes:
As shown in the block diagram in FIG. 4, the command potentiometer P. , operating position detection potentiometer P2,
It consists of resistors R,, R2 which together with these potentiometers constitute a bridge circuit, a servo amplifier A which receives the output signal from the bridge circuit as an input signal, and a servo motor M whose operation is controlled by the output signal from this servo amplifier A. . The command potentiometer P, includes a slider a that interlocks with the aperture ring 18 of the aperture mechanism section described above,
The potentiometer P2 is provided to detect the aperture position, and the operating position detection potentiometer P2 is connected to a servo motor M.
The servo motor M is provided with a slider b that is interlocked with the servo motor M, and is provided so as to detect the operating position of the servo motor M. The servo motor M is driven by a gear 47 meshing with the main gear 43 as shown in FIG.
It is provided to drive the. Also, S
, are switches between the bridge circuit and the servo amplifier A. Next, the operation of the zoom lens configured as described above will be explained below. This zoom lens can perform zooming by pushing and pulling the operating rod 23, that is, pushing it for telezooming and pulling it for wide zooming. It is also the same operation 23
Focusing can be performed by rotating the , and since this operation is already well known, it will be omitted here.

In this way, the zoom lens performs zooming through the operations described above, and its zoom range is limited and adjusted by the configuration described above.

That is, by rotating the aperture ring 18 to determine the aperture value while the switch S is closed, the command potentiometer P is operated in conjunction with the aperture ring 18, and the bridge circuit is brought into an unbalanced state. Become. This bridge circuit is in an unbalanced state, and power is supplied to the servo motor M via the servo amplifier A to drive it, causing the main gear 43 to rotate via the gear 47. At the same time, the operating position detection potentiometer P2 is operated, and the power supply to the servo motor M is cut off when the bridge circuit returns to an equilibrium state. By the rotation of the main gear 43, the zoom operation amount adjustment section is
A wisteria-shaped stopper member 42 rotated by a sheep gear 43
is engaged with the bearing member 41 to move forward and backward into and out of the rotary cylinder body 22, and serves to determine the push operation amount of the operation lever 23, that is, the telezooming operation amount. At the same time, in the zoom operation amount adjusting section, the stopper member 45 is rotated in the circumferential direction about the optical axis by the main gear 43, and the stopper part 45 facing the rotation path of the stopper receiving part 16b of the cam cylinder 16
5a, and the amount of rotation of the cam cylinder 16, that is, the amount of rotation corresponding to telezooming. Therefore, in this zoom lens, by rotating the aperture ring 18 to determine the aperture value, the amount of zoom operation towards the telephoto side and the amount of zoom operation during telezooming are adjusted, and the aperture value and the servo motor By predetermining the amount of rotation of M, a state can be set in which zooming to a zoom ratio region where the aperture value decreases can be automatically prevented. This makes it possible to safely use the lens while avoiding zooming into an area where the aperture F-number falls, which is the second usage mode described above.

Further, when the switch S is opened and the adjustment knob 40 is rotated, the main gear 43 can be rotated arbitrarily, and the zoom operation amount adjustment section and the zoom operation amount adjustment section are synchronously operated. The desired zoom range can be set.

In other words, this zoom lens can be used in the first mode of use, which ignores the drop in the aperture F value and fully utilizes the zoom function of the zoom lens, even within the range where the aperture F value can be kept constant. The third usage mode is to limit the range and avoid excessive zooming, and the fourth usage mode is to ignore the slight drop in the aperture value and extend the limited range of the third usage mode to the area where the aperture value drops. It is possible to realize all usage modes. This opens the switch S and transfers the aperture value information to the servo motor M.
This was achieved by freely manually adjusting the operating knob 40 so as not to allow the water to flow. As is clear from the above explanation, according to the zoom lens according to the present invention, the aperture value is adjusted according to the aperture value so as to prevent zooming to an area where the aperture value falls on the telephoto side of the zoom range. The zoom range that is kept constant is automatically adjusted, and zooming can be safely performed within the range where the aperture value is kept constant.

Furthermore, since the zoom range can be adjusted manually by cutting off aperture value information, this zoom lens can prevent unnecessary excessive zooming to the telephoto side at a high zoom ratio. It can be set to perform zooming that is suitable for the subject. As described above, the zoom lens according to the present invention allows the zoom range to be arbitrarily adjusted depending on the purpose of use, and is extremely effective in operation for high zoom ratio zoom lenses, which have been in increasing demand in recent years. It is something.

Moreover, according to the zoom lens according to the present invention, it is possible to synchronously adjust the zoom operation amount of the operation section and the zoom operation amount of the main body, reducing the burden on the members that adjust the zoom range, and especially for TVs. This is extremely effective for large zoom lenses such as camera zoom lenses. By the way, in the above embodiment, the zoom range is adjusted by manual operation regardless of the aperture value, but it is also possible to perform remote control by servo control. It goes without saying that the zoom lens according to the present invention is not limited to the one embodiment described above.

Furthermore, in the above explanation, we have explained that the range on the tele side of the zoom range is adjusted, but of course it is also possible to adjust the range on the wide side. It is also conceivable to adjust the telephoto side of the zoom range, and the configuration that realizes this can be achieved by adding improvements to the configuration of the above embodiment. The gist of the present invention is not only to do so.

Furthermore, in the above-mentioned embodiment, an operation method called a one-touch, two-operation method was exemplified, but it is also possible to use a type in which focus and zoom are performed by separate operation sections, or a type in which zooming is performed by servo control. Needless to say, it can be applied even if it is a thing. As explained above, the zoom lens according to the present invention can be easily realized by making slight improvements to known zoom lenses, and the effects obtained thereby, especially in terms of operation, are extremely It's big.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the relationship between aperture value and zoom ratio, FIG. 2 is a partially sectional side view showing the main parts of an embodiment of a zoom lens according to the present invention, and FIG. 2 and 4 are block diagrams of a control device applied to an embodiment of the present invention. 16...Cam cylinder, 16b...Stopper receiving part, 21...Stationary frame, 22...
・Rotating cylinder, 23... Operating rod, 25... Sliding body, 26... Rotating body, 27... Gear, 3
0...Wire 1, 40...Operation Mami, 4
2...Shaft-shaped stopper member, 45...
Stopper member, 45a... Part of stopper, 4
5b...Tooth portion, 18...Aperture ring, P,
...Command potentiometer, P2...
・Potentiometer for detecting operating position, M...Motor, 4
7...Gear. Younger brother/Diagram OZ diagram Demon 3 diagram Demon 4 diagram

Claims (1)

[Claims] 1. In a zoom lens in which a movable zoom lens group is moved in accordance with the operation amount of the zoom operation member and the aperture value changes at least in the telephoto side zoom region, a zoom operation amount adjustment member facing into the movement path of the zoom operation member. A motor for driving the adjustment member, a command potentiometer linked to the aperture value setting means, and a servo circuit for driving the motor by the output of the potentiometer are provided. A zoom lens characterized in that an adjustment member is configured to be automatically controlled.