JPS6244727A - Projecting device for microfilm reader - Google Patents

Abstract

PURPOSE:To perform switching to desired magnification easily and speedily and to reduce the cost by providing plural projection lenses which differ in power and also providing a lens turret, a turret locking mechanism, and a prism position changing mechanism. CONSTITUTION:When the lens turret 7 is swiveled, the turret locking mechanism TSM locks the lens turret 7 so that the center of a projection lens having different power coincides with the center of projection luminous flux to a screen. An image forming lens having different magnification, on the other hand, it set at a position of distance from a film surface corresponding to the power because of difference in focal length, but the position relation between a prism 4 for image rotation and each image forming lens is made constant by moving the prism 4 for image formation in the direction of projection luminous flux to the screen by a prism position changing mechanism PMM, thereby reducing a spread of the luminous flux incident on the prism for image rotation at any time. Therefore, a projection image is rotated by the same prism for image rotation.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a projection lens that enlarges and projects an image on a microfilm irradiated by a light source onto a screen, and a projection lens that rotates around the center of a beam of light projected onto the screen. The present invention relates to a microfilm reader projection device equipped with a movable image rotation prism.

[Conventional technology]

In microfilm, the imprinted image is generally rectangular, but its longitudinal direction does not always follow a fixed direction.

Further, the longitudinal direction of each image does not always match the vertical direction of the original image imprinted.

Therefore, when projecting an image onto a screen, for example, in order to always view characters etc. in an erect state, a configuration is required to align the vertical direction of the original image with the vertical direction of the screen.

In addition, especially for reader printers that have the function of enlarging copying onto copy paper in addition to the function of projecting onto a screen,
Since the orientation of the prepared rectangular copy paper is constant, the above-described configuration is used to align the longitudinal direction of the image with the longitudinal direction of the copy paper.

As one of such configurations for rotating an image during image projection, one is known in which an image rotation prism made of a trapezoidal prism is interposed in the projection optical path. In other words, by utilizing the optical property of the trapezoidal prism that the projected image rotates around the same axis by a rotation angle that is twice the rotation angle around the vertical axis, the image rotation prism can be rotated by plus or minus 45 degrees. By rotating the projection image, the projected image can be rotated by plus or minus 90 degrees.

On the other hand, a microfilm reader is required to have a function of varying the magnification of the projection lens in order to enlarge and project only a necessary portion of the image at a desired magnification. As a simple configuration for this purpose, one is known in which projection lenses with different magnifications are replaced as appropriate.

By the way, in a microfilm reader having an image rotation prism as mentioned at the beginning, the conventional method for replacing the projection lens as described above is to prepare an image rotation prism for each projection lens with a different magnification, and then replace those projection lenses. The lens unit was a combination of a prism for rotating an image and an image rotation prism, and was integrated into an interchangeable lens unit.

[Problem that the invention seeks to solve]

However, in the case of such a conventional configuration, an image rotation prism is required for each imaging lens with a different magnification, which makes the configuration for projecting onto a screen with different projection magnifications expensive. It was something that would become.

In view of the above-mentioned circumstances, an object of the present invention is to provide a structure for rotating an image during projection and varying the projection magnification in an advantageous manner in terms of cost.

[Means for solving problems]

The characteristic configuration of the microfilm reader projection device according to the present invention is that a plurality of projection lenses with different magnifications are provided for enlarging and projecting the image on the microfilm irradiated by a light source onto a screen, and the plurality of projection lenses are rotated from the center of rotation. A lens turret that holds the lens turret at an equidistant position, a turret locking mechanism that locks and fixes the lens turret in a state where the center of each projection lens coincides with the center of the beam of light projected onto the screen, and a turret locking mechanism that allows the lens turret to rotate. Accordingly, a prism position changing mechanism is provided for moving the image rotating prism, which is rotatable around the center of the projection beam onto the screen, in the direction of the projection beam.

[For production]

In other words, when the lens turret is rotated, the lens turret is locked by the turret locking mechanism so that the centers of projection lenses of different magnifications are successively aligned with the center of the beam of light projected onto the screen. Therefore, while visually checking the magnification of the image projected on the screen,
Images on microfilm can be enlarged and projected onto a screen at a desired magnification.

On the other hand, since these imaging lenses with different magnifications have different focal lengths, they are positioned at distances from the film surface according to the magnifications, but as the lens turret rotates to change the magnification, By moving the image rotation prism in the direction of the projected light beam onto the screen using the prism position changing mechanism, the positional relationship between the image rotation prism and each imaging lens is kept constant, and the incident light on the image rotation prism is Since the spread of the light beam can always be kept small, the same image rotation prism can rotate the image during projection even if the magnification is different.

〔Example〕

The present invention will be described in detail below based on the drawings.

FIG. 2 is a schematic diagram of an optical system of a microfilm reader printer, which is an example of a microfilm reader equipped with a projection device according to the present invention. Since this optical system itself is well known, it will be briefly explained.

This microfilm reader printer has two modes: a reader mode in which an image (not shown) on a microfilm (+") is enlarged and projected onto a screen (1), and a print mode in which an enlarged copy is made on recording paper using an electrophotographic process. It is possible to switch.

In either mode, the microfilm (F) is irradiated by a light source (2) consisting of a halogen lamp.

The projection light beam transmitted through this microfilm (F) passes through a projection device (P) having a projection lens (3) and an image rotation prism (4), and then passes through a first mirror (5).
a).

In the case of reader mode, the projected ray flux after reflection is
After being reflected by the second mirror (5b) and the third mirror (5c), it reaches the screen (1). This results in
The image is enlarged and projected onto the screen (1). Furthermore, in the print mode, the second mirror (5b) rotates and retreats to the position shown by the imaginary line in the figure. The projection light beam reflected by the first mirror (5a) is reflected by the fourth mirror (5d) and the fifth mirror (5e), and then is reflected by the photoreceptor drum (6).
). Then, as the first mirror (5a) and the fourth mirror (5d) move rightward in the figure, an electrostatic latent image is formed on the photosensitive drum (6).

An enlarged copy of the image is then obtained on recording paper (not shown) by means of well-known electrophotographic processes.

The image rotation prism (4) is a trapezoidal prism, and is configured to rotate around the center (Rc) of the projection light beam after passing through the microfilm (F).

In other words, the vertical direction of the original image imprinted on the microfilm (F) does not always match the vertical direction of the screen (1), while the longitudinal direction of the image does not always match the longitudinal direction of the recording paper. Not exclusively. Therefore, in order to prevent the inconvenience that the image projected on the screen (1) becomes sideways in the reader mode, or that the necessary image protrudes from the recording paper in the print mode, the optical properties of the trapezoidal prism are By using the fact that the projected image rotates around the same axis by a rotation angle that is twice the rotation angle around the vertical axis, the projected image can be rotated by plus or minus 45 degrees. This allows it to be rotated plus or minus 90 degrees.

In addition, this microfilm reader has three different magnifications.
Two imaging lenses (3A), (311), (3C
), and each of these imaging lenses (3A), (
By switching between 3B) and 3C, the image on the microfilm (F) can be projected onto the screen (1) at different magnifications or copied onto recording paper. Next, the configuration for this purpose will be explained together with the image rotation prism (4) described earlier.

As shown in FIG. 5, each projection lens (3A), (3
B).

(3C) is the lens body (3aa), (3ab)
, (3ac) and a male threaded part (3ha) with a thread groove formed on its outer periphery, (3bb),
(3bc), Snake male screw part (3ha).

(3bb), (3bc), and a cylindrical part (3ca), (3cb), which is integrally formed with and has a cylindrical outer peripheral surface.
(3cc), and this cylindrical part (3ca), (3
cb) and (3cc), the gear part (3cc) is integrally formed with the
It consists of da), (3db), and (3dc).

In addition, gear parts (3da), (3db), (3d
c) has tapered parts (3ea) and (3eb
), (3ec).

Then, as shown in Fig. 1, this projection lens (3A)
, (3B), and (3C) are held in a lens turret (7) in a state where they can be moved in the direction (D) of the beam of light projected onto the screen (1).

As shown in Fig. 3, this lens turret (7) has
Fitting parts (7aa), (Tab), (7ac) and female thread parts (7ba), (7bb), (7bc)
A lens holding part (7^) consisting of.

(7B) and (7C) are placed at positions equidistant from the rotation center (Y) of the lens turret (7) at 1 in plan view.
Three pieces were formed with different phases at 20 degrees. and,
Each lens holding part (7A), (7B), (7C)
In addition, the three projection lenses with different magnifications (
3A), (3B).

(3C) will be held. FIG. 1 shows a state in which the first projection lens (3A) is held by the first lens holder (7A). That is, the first lens holding part (
The fitting part (7aa) of the first projection lens (3
The cylindrical part (3ca) of 8) fits, and the female thread part (7ha)
The male screw portion (3ha) of the first projection lens (3A) is screwed into the .

The gear portion (3da) of the projection lens (3A) meshes with the lens fine movement gear (8). This lens fine adjustment gear (8) is linked to a manually operated fine adjustment knob (not shown), and rotation of this fine adjustment knob rotates the projection lens (3A) around its center (XA). By doing so, the projection lens (3A) can be moved in the direction of the projection light beam (b). In other words, the configuration is such that the projection lens (3^) can be focused by the above-mentioned operation.

The lens turret (7) mentioned above has its center of rotation (Y)
i on the turret holder (9) so that it can rotate freely around the
It is fitted inside. And lens turret (7)
A gear portion (7c) integrally formed with the turret rotation gear (10) is engaged with the turret rotation gear (10). This turret rotation gear (10) is linked to a manually operated turret rotation knob (not shown), and by turning this turret rotation knob, the lens turret (7) is rotated to the rotation center (Y).
It is constructed so that it can be swiveled around. Note that this turret rotation gear (10) and the lens fine movement gear (8) mentioned above are both externally fitted onto a shaft (12) that is fixed to the turret holder (9) with an E ring (11). is positioned.

In addition, as shown in FIGS. 3 and 4, each lens holding portion (7) is
Three slit-shaped notches (7da), (7db), and (7dc) are formed on the outer surface of the lens turret (7) on the opposite side from A), (7B), and (7C). On the other hand, as shown in Fig. 1, the turret holder (
9), on the side opposite to the center (Rc) of the projection ray bundle with respect to the center of rotation (Y) of the lens turret (7), biased inward by a leaf spring (13). In this state, the click ball (14) is secured with the screw (15).

In other words, the lens holding part (7A) of the lens turret (7)
, (7B) and (7C).

(3B), (3C) center (Xa), (Xs)
, (Xc) coincides with the center (Rc) of the projection ray bundle, the click ball (14) touches each notch (7cja).
, (7db), and (7dc), and the lens droop 7) (7) can be locked and fixed at that position. That is, three notches (7da),
(7db), (7dc), and a click ball (14) biased by a leaf spring (13) and secured by a screw (15) constitute a turret locking mechanism (TSM).

Therefore, by rotating the lens turret (7), projection lenses (3^), (3B) with different magnifications can be obtained.

(3C) is sequentially applied to the beam of light projected onto the screen (1), and while visually checking the magnification of the image on the microfilm (F) projected onto the screen (1), the image is quickly projected at the desired magnification. It is possible to manifest the state.

Further, although not shown, the turret holder (9) is configured to be detachable from the main body of the microfilm reader printer. That is, the three projection lenses (3A) and (3B) with different magnifications described above.

(3C) is designed so that it can be replaced with a turret holder that holds three projection lenses with different magnifications.

Moreover, as already explained, this projection device (P) includes the above-mentioned three imaging lenses (3A), (3B), (
3C), it also has an image rotation prism (4).

Specifically, as shown in FIG. 1, this image rotation prism (4) is a trapezoidal prism, and the prism holder (16
) is maintained by. This prism holder (16
) is fixed to the reader printer main body side by the prism holder support frame (17), so that the center (Rc) of the projected light beam is
It is supported so as to be rotatable around it and to be slidable in the direction (0) of the projection light beam.

A gear portion (16a) integrally formed with this prism holder (16) meshes with a prism rotation gear (18), and an image rotation knob (not shown) that is interlocked with the prism rotation gear (18). The image rotating prism (4) can be rotated around the center (Rc) of the projected light beam by operating the prism (4). That is,
The image can be rotated in the reader mode and print mode described above by operating the image rotation knob.

Each projection lens (
3A), (3B), and (3C) have different magnifications, so the lens body (3aa) shown in Figure 5
.

The distance D') between the apex on the film side of (3ab) and (3ac) and the film (F) is the projection lens (3A),
(3B) and (3G) will be different. Therefore, each projection lens (3^), (3B), (3
C) are attached to the lens turret (7) at different positions in the direction (D) of the projection light beam. On the other hand, in order to make the image rotation prism (4) compact, it is preferable to minimize the spread of the incident light beam as much as possible.

Therefore, the projection lens (3A
), (3B), and (3C) change,
The image rotation prism (4) is attached to the projection lens (3A) as much as possible.
).

It is necessary to locate it close to (3B) and (3C).

Therefore, the positioning of the above-mentioned prism holder (16) with respect to the direction (D) of the projection light beam is performed using the projection lens (3A).
, (3B), (3G) gear part (3da),
(3db), (3dc) by bringing the top surfaces into contact with their bottom surfaces,
4) and projection lenses (3A), (3B), (3C
) is configured so that the positional relationship with the

In addition, as shown in FIGS. 1, 3, and 4, when rotating the lens turret (7), the prism holder (1)
6) by coming into contact with the bottom of the prism holder (
16) adjacent projection lenses (3A) and (3B) while moving in the direction (D) of the projection ray bundle.

Gear part of (3C) (3da), (3db), (
Three guide parts (Tea) leading to the top surface of 3dc),
(7eb), (7ec), lens turret (7)
On the top surface of, each lens holding part (7^) in plan view,
(7B) and (7C) along the circumference including the center.

In other words, projection lenses (3A) with different magnifications, (
3B).

(3G) (7) Center (XA), (Xs), (
Xc) is the center (Rc
), the projection lenses (3A), (3B), with different mounting positions in the direction (D) of the projection light beam
The prism holder (16) moves in the direction (D) of the projection light beam so that the distance between the prism (3C) and the image rotation prism (4) is always constant. Therefore, even if the projection lenses (3A), (3B), and (3C) have different magnifications, the image can be rotated using the same image rotation prism (4), and this projection device ( P) can be provided at low cost.

The movement of the image rotation prism (4) in the direction (D) of the projection light beam due to the rotation of the lens turret (7) described above is shown in a developed view in FIG.

The magnification of each projection lens (3A), (3B), (3C) is [45X], [40x], [32X], respectively.
X], then each projection lens (3^), (3B)
, (3C) need to be positioned at different positions by about [3 dragons] in the direction (D) of the projection light beam (vertical direction in the figure). In the figure (xA), (XIl).

(Xc) are each projection lens (3^), (31
3) is the center of (3C), and this center (Xa)
, (L+), (Xc)
3A), (3B), and (3C) are shown by two-dot chain lines in the figure. Then, each adjacent projection lens (3
^) , (3B) , Center (XA) of (3C) ,
Between (X,) and (ni,), there is the guide part (Tea) and (7eb) explained earlier.

(7ec) will be located.

As explained earlier, the prism holder (16) actually has its center aligned with the center (Rc) of the beam of light projected onto the screen (1) as the lens turret (7) rotates. It is designed to move up and down. However, if we consider only the amount of movement of the projection ray bundle in the direction (D), as shown in the figure, the adjacent projection lenses (3A),
Gear part (3da) of (3B), (3C), (
3db), an inclined line (ta) connecting the centers of (3dc)
.

(tm), which is the same as moving on (t, c). For example, moving the prism holder (16) to the right in the figure corresponds to the operation of rotating the lens tower (7) counterclockwise in FIG. 4.

That is, when the lens turret (7) is rotated counterclockwise in FIG.
The projection lens (3A) is removed from the upper surface of the gear portion (3da) and transferred to the upper surface of the first guide portion (Tea). When the rotation angle of the lens turret (7) reaches 120 degrees, the prism holder (16) is moved to the gear part (of the second projection lens (3B)).
3db). After that, the lens turret (7)
As the prism holder (16) rotates, the prism holder (16) touches the top surface of the second guide section (7eb), the top surface of the gear section (3dc) of the third projection lens (3C), and the top surface of the third guide section (7ec). The light passes along the upper surface and moves to the upper surface of the gear portion (3da) of the first projection lens (3A) again.

Then, the prism holder (16) holds each projection lens (3
Center (XA) of A), (3B), (3C),
(xg), (χ,) is the center of the projection ray bundle (Rc)
In the defeated state, they are located as shown by the two-dot chain lines in the figure.

That is, each projection lens (3A), (3B), (3
C) Gear part (3da), (3db), (3d
c) and the guide parts (Tea), (7eb), (7ec) formed on the lens turret (7) constitute a prism position changing mechanism (PMM).
Ru,.

3, which is the movement locus of the bottom surface of this prism holder (16).
The inclination angle of the three inclination lines (LA), (LIl), (LC) (
φA) 1 (φ3), (φC) are each guide part (Tea)
, (7eb) and (7ec) are the inclination angles of the upper surfaces. The inclination angle (φA) of the first guide part (Tea) and the second guide part (Tea)
As mentioned earlier, the inclination angle (φB) of the guide portion (7eb) is the difference in height between the first projection lens (3A) and the second projection lens (3B), and the difference in height between the first projection lens (3A) and the second projection lens (3B). (3B
) and the third projection lens (3C) are approximately [3C].
■] from the rotation center (Y) of the lens turret (7) to each projection lens (3A), (3B), (3C)
(7) If the radius (r) to the centers (xa), (xm), and (XC) is [15 dragons], they are all about [5°3
0′]. Further, the inclination angle (φC) of the third guide portion (7ec) is approximately [10°50'].

Each guide part (Tea), (7eb), (7ec
), (φ), (φC) can be reduced by increasing the radius (r) to the extent that it does not hinder the compactness of the projection device CP).

In this case, the prism holder (16) can be moved more smoothly as the lens turret (7) rotates.

In addition, in the projection device (P) in this example,
As shown in FIG. 5, each projection lens (3A), (3
B), (3C) gear part (3da), (3db
), on the top surface of (3dc), there is a tapered part (3ea),
(3eb) and (3ec) are formed, and when the lens turret (7) starts turning, each gear part (3da)
, (3db), (3dc,) and the prism holder (16) are prevented from becoming difficult to rotate the lens turret (7).

In addition, each guide part (7ea), (7eb), (
7ec), and each projection lens (3A), (3B)
, (3C) gear part (3da).

(3db) and (3dc) are each made of a resin having a small coefficient of friction (eg, fluororesin or polyacecool), so that the prism holder (16) can be moved smoothly.

On the other hand, as shown in Fig. 1, the prism rotation gear (18
) on the gear part (16) on the prism holder (16) side.
It is formed sufficiently larger than the tooth width in a). In other words,
Projection lenses (3A) with different magnifications.

(3B) and (3C) are configured so that the image rotation prism (4) can be rotated reliably at all times when used by appropriately switching between them.

In addition, the tooth width of the lens fine adjustment gear (8) is set so that fine adjustment can be made even when the projection magnification is different.
), (3B), (3C) gear parts (3daL
(3db) and (3dc) can all engage together, and the projection lens (38) and (3B
) and (3C) in length.

In addition, in FIG. 1 and FIG. 3, (7fa).

(7fb) and (7fc) are the projection lenses (3A) and (3B) from the light source (2).

In order to regulate the flux of light incident on (3C), a flux regulating hole is formed in the lens turret (7) along with the lens holding parts (7A), (7B), and (7C), and
In Fig. 1, (9a) is the center (Rc) of the projection ray bundle.
Light flux regulating holes (7fa), (7fb), formed in the talent holder (9) with their centers aligned with
Holder side transmission hole with a slightly larger diameter than (7fc), and
(10aa).

(10ab) and (10ac) are projection lenses (3A)
, (3B), (3C) centers (XA), (L
+), (Xc) coincides with the center (Rc) of the projection ray bundle, and the gear side is formed on the turret rotation gear (10) so that its center coincides with the center (Rc) of the projection ray bundle. It is a transparent hole.

FIG. 7 shows the planar positional relationship of the lens fine movement gear (8), the turret rotation gear (10), etc. described so far.

In FIG. 7, (7) is a lens turret, and (9) is a turret holder. The above-mentioned projection lenses (3A) and (3B) are provided on the bottom surface of the lens turret (7).

(3C) each ray flux regulation hole (7fa), (7fb)
, (7fc) are provided.

Gear part (7c) integrally formed with lens turret (7)
is engaged with the turret rotation gear (10). This turret rotation gear (10) has the above-mentioned three
Two gear side transmission holes (10aa) and (10ab).

(10ac) is formed. Each projection lens (3A)
.

(3B), (3C) gear part (3da), (3
db), (3dc) are turret rotation gears (10
) can be interlocked with a lens fine movement gear (8) fixed to the same shaft (12). In the figure, the gear part (3da) of the first projection lens (3A) is connected to the lens fine movement gear (
8) Shows a state of L-shaped occlusion.

Then, as shown in FIG. 8, the above-mentioned projection device (
The turret holder (9) containing P) is attached to the turret holder support frame (19) fixed to the reader printer main body.
It is attached so that it can move freely in the vertical direction.

That is, two slit-shaped notches (9b) extending in the vertical direction are formed on the outer circumferential surface of the turret holder (9), with the phases being 180 degrees different from each other. On the other hand, the turret holder support frame (19) has a pair of arm parts (19a), and a protrusion (19b) provided on the inner side of each arm part (19a) is connected to the notch of the turret holder (9). Department (
9b).

Although not shown, by moving the turret holder (9) downward, the moving microfilm (F) is brought into contact with the glass plate that presses it from above, and a weight is used to prevent the microfilm (F) from lifting up. It is now possible to function as a

On the other hand, the prism holder (16) is attached to be movable in the vertical direction by a prism holder support frame (17) fixed to the reader printer main body. That is,
As with the turret holder, use the prism holder (16
) are formed with two slit-shaped notches (16b) extending in the vertical direction and having a phase difference of 180 degrees from each other. On the other hand, the prism holder support frame (17)
has a pair of arm portions (17a), and a protrusion (17b) provided on the inner side of each arm portion (17a) fits into a notch of the prism holder (16).

In the figure, (4) is an image rotation prism, (8) is a lens fine movement gear, and (10) is a turret rotation gear.

FIG. 9 shows another embodiment of a projection device (P) according to the invention.

In this example, three projection lenses (3Δ),
(311) and (3C) are held by the lens turret (7) with substantially the same configuration as in the previous embodiment. The prism holder (16) holding the image rotation prism (4) has a pair of pins (16c) on its outer circumferential surface having a phase difference of 1 soi, and a prism fixed to the reader printer main body (not shown). The holder support frame (17) is fitted with a pair of vertical slits (17c) so as to be movable in the projection light beam direction (D).

In this embodiment, the guide parts (Tea), (7eb), (7ec) made of plate spring members are screwed to the lens turret (7). In other words,
As shown in FIG. 10, as the lens turret (7) rotates, the bottom surface of the prism holder (16) moves to each guide portion (T).
ea), (7eb), and (7ec), but as a result of the fine adjustment, the position of the top surface of each projection lens (3A), (3B), and (3C) may change slightly. However, this guide part (made of a plate spring member)
Tea).

(7eb) and (7ec) are configured to allow smooth movement of the prism holder (17).

In addition, in the previous embodiment, three projection lenses (3A),
The lens turret that holds (3B) and (3C) (
9), but in this embodiment, the projection lenses (3A), (3B),
(3C) are configured so that they can each be replaced with different projection lenses.

Incidentally, the same parts as in the previous embodiment are simply given the same reference numerals and the explanation will be omitted.

In the previous two embodiments, the lens turret (7) has three projection lenses (3^) with different magnifications.

The one retaining (3B) and (3C) was explained. Alternatively, the number of projection lenses may be increased. In addition, the rotation of the lens turret (7), the slight movement of each projection lens (3A), (3B), (3C) in the direction (0) of the projection light beam, and the image rotation prism (4)
) was configured to be performed manually in the previous two embodiments, but instead of this, the turret rotation gear (10) and the lens fine adjustment gear (8)
, and the prism rotation gear (18) is interlocked with separate drive devices or the same drive device via separate transmission mechanisms, and these drive devices are driven by operating a manual operating tool. Accordingly, these operations may be performed automatically.

Further, the present invention is applicable not only to the microfilm reader printer described in the previous embodiment but also to microfilm readers that do not have the function of copying images.

〔Effect of the invention〕

As described above, the microfilm reader projection device according to the present invention holds a plurality of projection lenses with different magnifications in a lens turret, and by rotating this lens turret, the center of the projection lenses with different magnifications can be adjusted. Since the lens turret is locked in a state in which the lens turret is sequentially aligned with the center of the beam of light projected onto the screen, it is extremely easy to switch to the enlarged projection state at the desired magnification while watching the projection state on the screen. It is a simple operation and can be performed quickly.

Furthermore, when the magnification is changed, the prism position changing mechanism moves the image rotation prism in the direction of the beam of light projected onto the screen, so even if the magnification is different, the same image rotation prism This makes it possible to use a single image rotation prism for each projection lens, which was previously required with different magnifications, and it has become possible to reduce the overall cost.

[Brief explanation of drawings]

The drawings show an embodiment of the microfilm reader projection device according to the present invention, in which FIG. 1 is a sectional view of the projection device, FIG. 2 is a schematic configuration diagram of the optical system of the microfilm reader printer, and FIG. 3 is a lens. FIG. 4 is a plan view of the turret, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a partially cutaway side view of the projection lens, and FIG. FIG. 7 is a schematic diagram showing the meshing relationship of gears, FIG. 8 is a perspective view of the projection device, and FIG. 9 is a perspective view of the projection device showing another embodiment.
FIG. 0 is an enlarged view of the main parts of the embodiment shown in FIG. 9. (1)...Screen, (2)...
Light source, (3A), (3B), (3C)...
...Projection lens, (4) ... Image rotation prism, (7) ... Lens turret, (F) ...
...Microfilm, (D)...Direction of the projection ray bundle, (Rc)...Center of the projection ray bundle, (x
a) , (X@), (XC) --- Center of projection lens, (Y) --- Center of rotation of lens turret, (TSM) --- Turret locking mechanism, (
PMM)... Prism position changing mechanism.

Claims (1)

[Claims] In a projection device for a microfilm reader, which includes a projection lens that enlarges and projects an image on a microfilm irradiated by a light source onto a screen, and an image rotation prism that is rotatable around the center of a beam of light projected onto the screen, A lens turret that is provided with a plurality of projection lenses having different magnifications and holds the plurality of projection lenses at positions equidistant from the center of rotation; a turret locking mechanism for locking and fixing the lens turret; and a prism position changing mechanism for moving the image rotation prism in the direction of the projection light beam as the lens turret rotates.