JPS60114850A - Anamorphic variable power copying method - Google Patents

Abstract

PURPOSE:To attain anamorphic variable power without reducing resolution by arranging a prism having no refractive power in one axial direction out of two axes rectangular to the axis of projected light and having refractive power in the other axial direction close to a projection lens in the projected light path and executing copying with different magnification values in the slit longitudinal direction and in the slit width direction respectively. CONSTITUTION:An image is transmitted to a photosensitive body 4 through the 1st mirror 13, the projection lens 14, the prism 10 arranged close to the projection lens 14, and the 2nd mirror 15. The projection lens is constituted so as to be moved to a specified magnification position and the 2nd mirror 15 is constituted to be deflected to absorb the change of the optical path generated by the variable power movement of the projection lens 14. Being arranged close to the projection lens 14, the prism 10 has almost the same size as the projection lens and has no refractive power in the slit longitudinal direction, but has refractive power in the slit width direction. The anamorphic variable field power beta2 is shown by the formula I and a required variable power beta2 is fixed by setting up the incident angle theta1 of the prism, the vertical angle alpha of the prism and the refractive index n of the prism properly.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an anamorphic variable magnification copying method in a slit exposure type copying system. Anamo quick variable magnification refers to a variable magnification method that copies a document at different magnifications in the vertical and horizontal directions. This anamorphic scaling can be used for design purposes to change the aspect ratio of characters and graphics, to reduce image size in only one direction to create a binding margin for copies, or to eliminate image loss when using forced separation. It is useful for many purposes. The present invention particularly relates to an analog quick variable magnification copying method using a prism.

Conventional technology A normal magnification method in which both the length and width of a document are multiplied by β is carried out by placing the projection lens at a position of β times and setting the scanning speed to Vβ (v: circumferential speed of the photoreceptor).

Here, by changing the relationship between the position of the projection lens and the scanning speed, copies can be made with different magnifications in the vertical and horizontal directions. For example, if the projection lens is placed at a position of β1 times, and the scanning speed is Vβ, β2, then the longitudinal direction of the slit is β1.
7) It is possible to obtain a copy that is β1β2 times larger in the width direction.

However, in the above method, the circumferential speed of the photoreceptor differs from the speed of the image moving on the photoreceptor, so the image is only slightly blurred.

In order to solve the above-mentioned reduction in resolution, it is sufficient to multiply the image by β2 only in the slit width direction, and for this purpose it is possible to use a cylindrical lens.

However, manufacturing long cylindrical lenses is difficult and extremely expensive.

Purpose/Summary The present invention has been made in view of the above, and an object of the present invention is to provide an anamorphic magnification method that can perform anamorphic magnification without reducing resolution, is easy to manufacture, and is low cost. do.

In order to achieve the above object, the present invention uses a triangular prism composed of a plane, and in particular, this prism is arranged near the projection lens.

EXAMPLE First, the aforementioned decrease in resolution will be explained with reference to FIG. FIG. 1 shows a slit exposure copying method for document movement. In order to perform anamorphic magnification, the projection lens (1) is placed at a position corresponding to the magnification β1, and the document (2) is placed in a slit exposure copying system with a width t. J Soto (31 to speed Xl/β113
On the other hand, the photoreceptor (4) is set to move at a speed of V.

Here, the time required for point A of the document (2) to pass through the slit (3) is as follows: E-4-=β1β2tV/β1β2V. The distance that the photoreceptor (4) moves with this time difference is L, = V, t = β1β2t.

On the other hand, during the above time period, point A of the original (2) moves to point A', and the image formed by the projection lens (1) placed at a position of 1 magnification β□ is from point B in the figure. Move with B5. The amount of movement L' of this image is LF = β1t.

Therefore, the displacement of the photoreceptor during movement of the document (2) from point A to point N causes a decrease in resolution.

Therefore, if the image is multiplied by β2 only in the slit width direction, the image movement chain becomes βLl=βt79Z2=L, and both coincide.

The Kihatsu EJ'l uses a triangular prism to change the magnification of the 71778 by a factor of 2 in the width direction, and FIG. 2 schematically shows a copying machine to which this invention is applied. The copying machine shown in FIG. 2 is of a movable document table type, and the document is placed on the document table (11) and moves at a speed described later. The moving document is illuminated by the 11α brightness device (12), and its image is reflected in the first mirror (13).
, a projection lens (14), a prism (10) placed near the projection lens, and a second mirror (15).
4). Here, the projection lens (14) is configured to be able to move to the designated magnification position, and the second mirror (15) is still configured to compensate for changes in optical path length due to the magnification movement of the projection lens (14). Configured to deflect and deflect for absorption. This projection lens (14) and the second
The mechanism for moving the mirror (15) is well known, so its explanation will be omitted.

Since the sum (lO) is placed near the projection lens, it has the same size as the projection lens, has no refractive power in the longitudinal direction of the slit, and has β2 times the refractive power in the slit width direction. It has a refractive power of By arranging the prism at this position, the prism can be made very small, with only the size of a Les tin surface.

Now, in such a configuration, the position of the projection lens (14) and the scanning speed of the document table when the circumferential speed of the photoreceptor is V are set as shown in Table 1 below.

Table-1 Here, in case ■, when the slit is multiplied by β1 in the longitudinal direction of the slit and β1β2 in the slit width direction, case
Indicates the case of multiplying. Although the magnification β2 of the prism is fixed, the magnification in the longitudinal direction or the magnification in the width direction can be arbitrarily set using a moving mechanism such as a document table moving mechanism and a projection lens that can arbitrarily change the magnification β□. I can do it.

Now, so far we have explained that the prism has a refractive power of magnification β2, but below we will explain the third aspect of this refractive power.
This will be explained using Figure 4.5.

Figure 3 shows two parallel principal rays L1 and L2 with a principal ray interval.
begins to enter the triangular prism (10) at an angle θ1, and the chief rays L□ and L2 are refracted and proceed as shown.

These two principal rays are the results of two image points (each principal ray of a linear beam).Here, we will explain image magnification, so we will explain only the principal rays.Now, in this case, according to Snell's law, The following relationship holds.

Sinθ1=nSinθ□′ ・・・・・・■θ2−α
-θf ・・・・・・■ n5in02= Sinθi,' -H・HH■ However,
n Refractive index of Ni prism α Apex angle of Ni prism θ, : First angle of incidence θ1' : First surface refraction angle θ2 : Second surface incidence angle 02' : Second surface refraction angle J'b' : Exit side principal ray Spacing Next, in FIG. 4, ■ indicates the position of one image formation when there is no prism. Here, when the imaging light of image (2) perpendicular to the principal ray enters the prism (10) in the above relationship, the principal rays L1 and L2 are P□→Q1→R1→t and P2→Q, respectively.
It passes through the optical path 2→R2→S2 and becomes an image 1'.

A light beam that passes through a substance with a refractive index of n has an imaged point extending further away than a light beam that passes through air. QIR□ is selected from the function 1 system of conversion intervals that indicates this as follows.

QIR□−P2Q2/n ・・・・・・■Therefore, PI
When Ql-"'-Q2 R2, the conversion interval of Pi QI R1 on chief ray L1 and P2 of chief ray L2J-
Q2 'R2 conversion intervals match. That is, after passing through the prism, the two RIR planes are at equal (converted) distance from the 2122 plane.

Here, if the deviation in the principal ray traveling direction on the principal rays RI, L2 is Δ, then the magnification β2 by the prism (10) is as follows.

Second, in Figure 5, the principal ray L2 after passing through the prism is extended into the prism, and its intersection with the first surface of the prism is defined as U2, and the perpendicular line F drawn from point R1 to this extension line is If the foot is V2, then 5IS2T2 and 5th in Figure 4.
Since △RIR and V in the figure are similar, △−x + Q2
V2...■Also, △P1. From P2Q engineering, x=-ノLtanθ1...Moreover, the chief ray L after passing through the prism from point Q2! ni″F
If the foot of the perpendicular line is Wo, then QI V2=RIW1=QIWI-QI R1...-
・■Here, QlWl is △Q, QIW from Q2W1
, = JLI t, nθ21 Furthermore, using the formula ■.

To calculate this, let Q1Q2-A, and let the foot of the perpendicular line drawn from point Q2 to the first surface of the prism be ΔQI Q.
I A2 and △P2 QI, sin α P2 QI −' cosol Since it can be expressed as A = /'-'/CO8θ2', this and the ■ formula % formula % The above ■, ■, ■, ■, [ [phase], β of equation 0 using equation 0
2 In the above equation O, θ, 'θ2θ2' is related to θ according to the relationship of the equation .■.■. Therefore, the desired magnification β2 can be determined by appropriately setting the incident angle θ□ on the prism, the apex angle α of the prism, and the refractive index n of the prism.

By the way, in the above description, the two principal rays are assumed to be parallel for the sake of simplicity. However, it goes without saying that even in the general case where the parallel objects are not parallel, magnification change by the prism occurs in the same way, and the magnification can also be determined according to the above-mentioned concept.

Similarly, the image before entering the prism is assumed to be perpendicular to the principal ray, but the same can be said if the image is not perpendicular to the principal ray. Assuming that the image is tilted by an angle φ as shown by the dotted line 0IP2 in FIG. 4, the above equation 0 is modified as follows.

In the present invention, since the prism is placed near the projection lens, anamorphic magnification can be more easily performed by changing the perspective. That is, the prism is rotated 90' around the optical axis of the projection lens. Figure 6A shows a state corresponding to Figure 2, and S
is a slit illumination area, and the first and second mirrors are omitted. FIG. 6B shows the prism (10) rotated by 90 degrees. The state shown in FIG. 6B is a state in which the slit has refractive power in the longitudinal direction and has no refractive power in the slit width direction. In this case, since there is no refractive power in the slit width direction, the above-mentioned reduction in resolution does not occur, and the relationship between the scanning speed and the projection lens is the same as in the normal case. That is.

When the projection lens is positioned at a magnification of β1, the scanning speed is Vc, and it is possible to obtain a copy of β1β2 times in the longitudinal direction of the slit and β times in the width direction of the slit.

In this case, the relationship between the projection lens position and scanning speed is the same as for normal magnification change, so anamorphic magnification change can be easily performed.

Furthermore, in the case of FIG. 6B, the position of the image is shifted to one side in the axial direction of the photoreceptor. This is shown in FIG. 7, which shows the optical path developed.

Therefore, this arrangement is advantageous for single-purpose uses such as forming blank areas for binding margins and forced separation.

On the other hand, if the prism is configured to be rotatable around the optical axis of the projection lens and configured to switch between the states shown in FIG. 6A and FIG. If you want to obtain a copy of the slit, select Case I or Case ■ in Table 1, and if you want to compress the image in the longitudinal direction of the slit and move the image to one side in the slit longitudinal direction, select Case B in Figure 6. There are advantages to being able to do so. If rotation can be performed in both forward and reverse directions, it becomes possible to select which side of the paper the image should be shifted to.

Now, if we go back to Equation 0 of f3Q or Equation 0, once it is decided to use a certain prism, the apex angle α and the refractive index n are determined, so in the end, the only variable in the equation is the incident angle θ1. Therefore, by changing this incident angle θ□, the anamorphic magnification β2 can be changed arbitrarily.

That is, the prism itself can be rotated around an axis parallel to the slit. FIG. 9 schematically shows this method. In FIG. 9, if the prism (10) is rotated from position A to position B and its angle is θ, then the angle of incidence at position A is θ1. and the angle of incidence θ at position B
Therefore, Vc has the following relationship. Note that the angle is positive in the counterclockwise direction.

θlb-θ1a-θL ・・・・・・[Phase] This formula and ■,
If the initial angle of incidence θ1a and rotation angle θL are determined by formulas ① and ①, θib, θ2b, and θ are determined, and by substituting these into formula O or 6', the magnification β2b of the position of B can be determined. I can do it. The center of rotation is preferably selected in such a way as to minimize the deviation of the imaging position, the tilt of the image, and the change in optical path length due to the rotation.

The above magnification change can be performed in the same manner in the case of FIG. 6B, and in this case, the position of the image can be shifted in the longitudinal direction of the slit, although there is a certain relationship with the magnification.

Incidentally, although the explanation so far has been based on the use of one prism, it is more advantageous in various respects to use two prisms.

In other words, in the case of a single prism, chromatic aberration and astigmatism occur,
Although the tilt of the image is still large, by using two prisms and making the apex angle smaller than that of one prism, the astigmatic difference can be reduced, and the direction of the apex angle of the two prisms can be changed. Conversely, chromatic aberration and image distortion can be canceled out. Figure 10 shows two prisms A.
(IOA) and (IOB) are used, the principal ray interval before entering the prism (10^) is I□, the principal ray interval within the prism (10A) is 6, and the prism (1
The principal ray interval between 0^) (IOB) is t3, and the prism (
If the interval between the principal rays emitted from the prism (10a) is L5 based on the interval between the chief rays in the prism (10a), the intervals between the respective chief rays have the following relationship. Incidentally, the incident angle, refraction angle, and apex angle of each prism satisfy the relationships of formulas (1), (2), and (2) above.

The final magnification β2o can be determined as follows. Further, the deviation Δ' of the chief ray can be determined in the same manner as in the case of the single prism described above. The image nods toward E1E2, FIF2, and - as shown by dotted lines in the figure, but as is clear from the figure, the final image inclination is much smaller than that of a single prism.

By replacing the system consisting of two prisms as described above with the prism (10) in FIG. 2, various aberrations etc. can be corrected and a better image can be obtained.

Further, this two-prism system (10') can be directly applied to the rotation of the prism shown in FIG. That is, the 11th
As shown in the figure, it is rotated from state (a) to state (b).

Furthermore, in the case of a two-prism system (10'), only one prism can be rotated. That is, the state (c) or (d) in FIG. 11 is established.

Table 2 shows the projection lens magnification, scanning speed, and magnification in the longitudinal and width directions in the same manner as Table 1.

Table 2 Here, the magnification of the fixed prism (IOA) on the projection lens side is β2A, and the magnification of the rotating prism (IOB) is β2B.

By rotating only one prism in this manner, it is possible to perform anamorphic magnification in which the aspect ratios are different and the image is biased to one side, and the number of usable aspect ratios increases.

As with the case of a single prism, the magnification of the -2 prism system (10') can be changed by rotating one or two prisms around an axis parallel to their ridges ( (See FIG. 11(a)), the magnification can be calculated using the application for the single prism described above, but it can also be used in the following way. In other words, when returning to normal magnification, in the case of a single prism system, it was necessary to remove the prism from the optical path and compensate for changes in the optical path length, etc., but in the case of a two-prism system, the incident angle and apex By appropriately setting the angle, it is possible to obtain the same refractive power, and there is no need to correct the optical path length. FIG. 12(b) shows the case where the prisms (10A) and (10B) are moved so that the magnification becomes the same. Furthermore, if the apex angles of the two prisms are the same, the two prisms will be in a bonded state as shown in Figure 12 (c), and the entrance surface and exit surface will be perpendicular to the optical axis of the projection lens. It can be set to be equivalent to flat glass that has no refractive power.

Table 3 shows the data in Figures 12 (a) and (b). Here, the apex angle and refractive index of both prisms are 15' + 1.5
It is 168. Also, the image plane tilt amount △ is 0. It is derived from the equation θ, and the incident angle θ1. θ3 is a prism (10
A010B).

Table 3 As shown in FIG. 13, by shifting the prism (10) in the direction of its refracting power, the image position can be shifted. In the case of FIG. 6, this means that the blank area (Z) can be adjusted, and it can also be used to correct the deviation of the imaging position that occurs when the prism is rotated.

Effects As described in detail above, in the exposure type copying method of the present invention, a refractive power is provided in the vicinity of the projection lens in the projection optical path in the direction of one of the two axes perpendicular to the projection optical axis. A prism with refractive power is installed in the other axis directions, and copies are made with different magnifications in the slit longitudinal direction and slit width direction. Anamorphic magnification can be performed, and as a result, a simple configuration and low cost can be achieved.

Indeed, if the prism is arranged so that it has refractive power in the slit width direction, the vertical and horizontal directions of anamorphic magnification can be switched by appropriately setting the projection lens position and the speed ratio between the scanning system and the photoreceptor.

Further, if the prism is arranged so as to have refractive power in the longitudinal direction of the slit, anamorphic magnification can be easily performed and the image position can be shifted in the longitudinal direction of the slit.

Furthermore, by rotating the prism around the projection optical axis, various anamorphic magnification changes can be achieved.

Furthermore, by rotating the prism about one axis parallel to the ridge line, the magnification of the prism, that is, the anamorphic magnification, can be arbitrarily changed.

Furthermore, if the prism is composed of two lenses, it is possible to correct chromatic aberration, astigmatism, and image tilt.

Furthermore, if at least one of the two prisms is rotated around the projection optical axis,
Furthermore, various anamorphic magnification changes can be performed.

Furthermore, by shifting the prism in the direction in which it has refracting power, the image position can be corrected or shifted.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining that the resolving power decreases with anamorphic magnification, Fig. 2 is a schematic diagram showing a copying machine to which the present invention is applied, and Fig. 3.4.5 shows the refractive power of the triangular prism. Fig. 6 is a perspective view schematically explaining an example of rotating the prism around the optical axis of the projection lens, and Fig. 7 is an optical path development showing the deviation of the image in the case of Fig. 6B. Figure, 8th
The figure shows a copy that has undergone anamorphic magnification according to the embodiment shown in Figure 6, Figure 9 is a diagram explaining the case where the anamorphic magnification is changed by rotating the prism, and Figure 10 shows two prisms. Fig. 11 is a schematic diagram of an example in which two prisms are used and either both prisms or one prism is rotated around the projection optical axis, and Fig. 12 is a schematic diagram of an example in which two prisms are used. FIG. 13 is an explanatory diagram of an embodiment in which the anamorphic magnification is made equal to the same magnification by shifting the prism. 1.14 Projection lens 2 Original document 4 Photoreceptor 10 , IOA, IOB ... Prism 10' ・
...Prism system applicant Minolta Camera Co., Ltd. Fig. 2 Fig. 4 n Fig. 5 Fig. 6 A Fig. 6 B Fig. 2 Dr JP-A-114850(8) No. 8vA Table Gochimata l's place IF Figure 6 Venue, meeting, page 1 continued O Inventor Haruhiro Hyodo 0 Inventor Hiroshi Nakamura @ Inventor Nobuo Kanai 2-3 Azuchi-cho, Higashi-ku, Osaka Osaka Kokusai Building Minolta Camera Co., Ltd. Osaka Osaka Kokusai Building, Minolta Camera Co., Ltd., 2-3 Azuchi-cho, Higashi-ku, Osaka, Osaka Kokusai Building, Minolta Camera Co., Ltd., 2-3 Azuchi-cho, Higashi-ku, Osaka

Claims (1)

[Claims] 1. In the slit exposure type copying method in which the image of the document scanned in a slit shape by the scanning system is projected onto the photoreceptor by the projection lens, one of the two axes perpendicular to the projection optical axis is placed near the projection lens in the projection optical path. An anamorphic variable magnification copying method characterized in that a prism is provided that has no refractive power in the axial direction of the slit and has refractive power in the other axial directions, and copies are made with different magnifications in the slit longitudinal direction and slit width direction. .