JPS6167030A - Exposing device of copying machine - Google Patents

Abstract

PURPOSE:To correct effectively the cosine biquadratic rule characteristics of an image forming lens in advance and to reduce the power source cost of a light source by distributing the quantity of light on a platen surface to the optical axis of the image forming lens symmetrically in a periphery more state on condition that a variable magnification copying machine is a corner register type. CONSTITUTION:When copy magnification is set to life size during exposure, a movable lamp unit 30 is arranged at each corner part of a housing bottom part 1b and flash light sources 22 and 23 of a fixed lamp unit 20 and a movable lamp unit 30 emit light beams, which reach the surface of a platen 3 directly or after being reflected by reflectors 24 and 35. At this time, more light is distributed to peripheries of the respective corner parts of the platen 3 because of the relation between main optical axes (n) of the reflectors 24 and 35, the distribution of the quantity of light on the surface of the platen 3 is in the periphery more state which is symmetric about the optical axis of the image forming lens 4, and the entire surface of a copy original 2 is lighted with this light quantity distribution. In this state, when the light quantity distribution is set as desired, the light quantity of original image light right after being passed through the image forming lens 4 is set nearly uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure device for a copying machine, and particularly to an exposure device of a type used in a variable magnification copying machine and employing a so-called full-surface exposure method.

[Conventional technology]

A conventional exposure device that employs a so-called full-surface exposure method in a copying machine has a housing (1) with a closed cross-sectional structure, as shown in FIGS. 9 and 1O, for example.
) is provided with a rectangular opening at the top (1a), and a platen (3) made of glass or the like is mounted on which the copy document (2) is placed in the car crest opening. A lens mounting hole is provided in the bottom (1b) of the housing, and an imaging lens (4) is mounted in the lens mounting hole, while a flash illumination means (S) is provided inside the housing (1). This is what happens. This type of exposure apparatus instantly illuminates the entire surface of the copy document (2) on the platen (3) using a flash illumination means (S) during exposure, and the original image of the document document (2) is illuminated by the flash illumination means (S). The image is projected onto a predetermined photosensitive surface (5) via an imaging lens (4).

By the way, in such a conventional exposure device, if the light intensity distribution of the projected image on the photosensitive surface (5) is uneven, unevenness or bright lines may occur in the copied image, which may impair the quality of the copied image. For this reason, it is necessary to maintain a uniform light intensity distribution of the projected image on the photosensitive surface (5).

In this case, the imaging lens (4) has a cosine fourth power side characteristic,
In other words, since the amount of original image light passing through the imaging lens (4) decreases by cos'θ depending on the angle of view (θ) with respect to the imaging lens (4), the The characteristics of the image lens (4) must be taken into consideration.

Therefore, in conventional exposure apparatuses, a flash illumination means (Sl
As shown by the solid line J in FIG. 11(a), the light intensity distribution on the platen (3) surface is given as a state with excessive periphery, and from this, the characteristics of the imaging lens (4) are corrected in advance. Then, as shown in Fig. 11 fbl, the photosensitive surface (
5) The light intensity distribution of the projected image above is kept uniform. As this type of flash illumination means (S), for example, as shown in FIG. The unit (6) is fixedly installed, and each lamp unit (6) is connected to a flash light source (7) (specifically, (7)
a) to (7d), and a reflector (8) (specifically 4; t(8a) to (
8d)), whereby the amount of peripheral light of the platen (3) is set to be larger than the central pattern of the platen (3) has already been provided.

[Problems to be Solved by the Invention] Although such conventional exposure equipment is based on a constant magnification type copying machine, this type of exposure equipment can be used to copy the negative corner of the platen (3). When applying this to a variable magnification copying machine with a corner registration type c (hereinafter referred to as corner registration type) with the positioning reference point (Ro) of the document (2) as the positioning reference point (Ro), the platen (3)
An operating groove (not shown) extending diagonally including the positioning reference point (Ro) is opened, and as shown by the one-dot chain line and the two-dot chain line in FIG. By appropriately moving the imaging lens 14),
The original image of the copy document (2) must be enlarged or reduced and projected onto a predetermined photosensitive surface (5). In this case, if the imaging lens (4) moves during zooming, the optical axis of the imaging lens (4) will deviate from the center of the platen (3), so as shown in FIG. 11 t11. Even if the light intensity distribution on the platen (3) surface is set as desired symmetrical with respect to the optical axis (2) of the imaging lens (4) at the same magnification, the light intensity distribution on the platen (3) surface at the time of zooming is set as desired. ) surface is the optical axis of the imaging lens (4) (
it becomes asymmetric with respect to (it). For this reason, when changing magnification, the characteristics of the imaging lens (4) tend to be insufficiently corrected, and the light intensity distribution of the projected image on the photosensitive surface (5) becomes uneven, resulting in poor copy image quality. A situation of loss occurs.

As a means to resolve this situation, the amount of light irradiated by the flash light source (7) constituting the lamp unit (6) is changed appropriately when changing the magnification, and as shown in FIG. It is conceivable to keep the light intensity distribution on the platen (3) surface symmetrical with respect to the optical axis (fh) (fh) of the imaging lens (4) even when changing the magnification, but this type is not suitable. In particular, when the imaging lens (4) moves from the same magnification position to the positioning reference point (Ro) @ during magnification, the image shown in FIGS. 9 and 11 (
As shown by the dashed line in a), the positioning reference point (R
The amount of light in the platen (3) area located near the diagonal point (R1) of o) must be significantly increased. In this case,
The above diagonal point (lamp unit (6) installed on the R1 side)
The amount of light irradiated from each of the flash light sources (7b) (7c) must be increased significantly, and the power consumption of the flash light sources (7b) (7c) increases accordingly. 7b) The problem of increasing power supply cost (7c) arises.

[Means and effects for solving the problems] This invention has been made by focusing on the above problems, and its problem is based on the premise of a corner register type variable magnification type copying machine. , while effectively preventing a situation where the power consumption of the light source itself increases significantly, maintaining the light intensity distribution on the platen surface in the desired state without being affected by the magnification change operation, and forming an image based on the light intensity distribution on the platen surface. An object of the present invention is to provide an exposure device for a copying machine that can effectively correct lens characteristics in advance. And in order to accomplish this task,
This invention is an improved flash illumination means disposed within the housing, in which a fixed lamp unit is fixedly installed corresponding to the corner or side edge of the platen located near the positioning reference point of the copy document. A movable lamp unit is movably installed corresponding to the other corner or side edge of the platen, and each of the lamp units is connected to a flash light source, and a region of the platen located near each flash light source is irradiated from each flash light source. and a reflector that distributes a large amount of light, while moving the movable lamp unit as the imaging lens moves at the time of magnification,
The movable lamp unit and the fixed lamp unit are arranged symmetrically with respect to the optical axis of the imaging lens at the time of magnification.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

The exposure device according to the embodiment shown in FIGS. 1 to 6 is used in a corner registration type variable magnification copying machine, and its basic configuration includes a housing (1) having a substantially rectangular closed cross-sectional structure; , a platen (3) installed in a rectangular opening provided at the top (1a) of the housing (1), and a platen (3) disposed inside the housing (1).
) and a flash illumination means (SJ) that instantly illuminates the entire surface of the copy document (2) on
) An imaging lens (4) is mounted so as to be movable along the longitudinal direction of an operating groove αα formed approximately in the center.

In this embodiment, the platen (3) has a surface on which a copy document (2) up to the so-called (A3) size can be placed, and the negative corner of the platen (3) It is given as a positioning reference point (Ro) for positioning the original (2). The operating groove 00+ extends symmetrically along a diagonal direction including the positioning reference point (Ro) of the platen (31) with the center of the housing bottom (1b) as a boundary.

Further, the flash illumination means (81) includes a fixed lamp unit ■ installed at the bottom (lb) of the housing (1) corresponding to the negative corner of the platen (3) on the side of the positioning reference point (Ro), and a platen Movable lamp units (to) (specifically (30a) to (3) installed at the bottom (1b) of the housing (1) corresponding to the other corners of (3)
0c)) The above fixed lamp unit ■ consists of
Lamp holder 0 on the bottom f'lb) of the housing (1)!
This lamp holder fixed υ? Uko holds the flash light source 4 bent at a substantially right angle via a holding bracket (c), and also arranges a reflector (2) on the non-platen (3) side of the flash light source (2).
The lamp holder eη is fixed to the lamp holder eη via a support (bracket). - 10,000, the movable lamp unit (g) is located at the bottom (l) of the housing (1).
In b), a pair of guide rails 0υ extending from the corner toward the fixed lamp unit ■ are integrally formed, and a lamp holder 0a is slidably mounted on each guide rail 0◇. The holder 6 holds the flash light source 01 bent at an approximately right angle with a holding bracket (
At the same time, a reflector (c) was placed on the non-platen (3) side of each flash light source 01, and each reflector (g) was fixed to the lamp holder Oa via a support bracket 0. It is something. Then, each lamp holder I- (reflector (C) 0→ in Figure 2O2 is attached to each flash light source as shown in Figure 8) 01
The main optical axis (n
1, so that a large amount of the irradiation light from each flash light source (2) is distributed to the predetermined area of the platen (3).

Further, the driving means O0 for driving each of the movable lamp units (7) is, for example, as shown in FIG. are (41a) to (41c)),
A guide pulley (6) for passing each drive wire 0]) to an appropriate position, a drive motor (-), and a drive motor (6).
three drive pulleys (specifically (44a) to (44c)) of different diameters which are connected and fixed to each shaft and to which the other ends of each drive wire (6) are respectively connected; and each movable lamp. It is composed of a spring that biases each unit (G) toward the fixed lamp unit (2). In this embodiment, the drive motor 03 is controlled by a microprocessor that outputs a control signal based on information from the copy magnification selection section, and during the same magnification and reduction ζ, each of the drive wires 0] ) are appropriately wound up against the biasing force of the spring, and each movable lamp unit (7) is set at the corner of the housing bottom (1b), while when enlarging, each of the above drive wires @υ is appropriately wound back. , each movable lamp unit (1) by the urging force of each spring 4.
is moved to the fixed lamp unit ■ side as appropriate, and the optical axis (Ql) of the imaging lens (4) during magnification (see Fig. 7 (bl); on the other hand, each movable lamp unit ■ is symmetrical with the fixed lamp unit 伽). It is designed to be placed.

Furthermore, as particularly shown in FIG. 6, the imaging lens (4) is supported via a movable plate lifting device (60) that moves back and forth along the operating groove (IG).

In this embodiment, the movable play 1 has a pair of support rails (51) supported and fixed to the housing bottom (1b).
A circular transmission port (not shown) is provided approximately in the center of the movable plate, and a guide tube (52) is provided around the transmission port. The imaging lens (
4) is fitted into the case (4a) so as to be movable up and down. In addition, the elevating device (60) has a pair of guide columns (61) erected on the movable plate, and a pair of guide pieces (62) on the case (4a) of the imaging lens (4). ), and by slidably mounting the guide piece (6z) on the guide column (61), the imaging lens (4) can be supported up and down. In FIG. 6, ('53) is a drive wire for advancing and retracting the movable plate flash, and ('53) is a holding spring that maintains the position of the movable plate 1 by following the amount of advance and retreat of the drive wire (58). (61) is a drive wire for raising and lowering the lifting device (6o), and (64) is a guide roller for passing the drive wire (68) to an appropriate position. The imaging lens (4) is set at the neutral position of operation #aa at the same magnification, as shown in FIG. The image is projected on the photosensitive surface (5) as it is, and when enlarging, the operating groove (IO) near the positioning reference point (Ro) is
It is set at a position higher than the same magnification position at one end edge, and enlarges the original image of a copy document (2) of (A4) size, for example, to (A,) size and projects it onto the photosensitive surface (5). On the other hand, at the time of reduction, as shown in FIG. 7(c), the other edge of the operation #ul is set at a position lower than the position at the same magnification.
The original image is reduced in size (A4) by l and projected onto the photosensitive surface (5).

Therefore, according to the exposure device of the copying machine according to this embodiment,
If you set the copy magnification to 1x at f during exposure, the 7th
As shown in Figure (al), after the movable lamp unit (■) is placed at each corner of the housing bottom (1b), each flash light source (2) of the fixed lamp unit (■) and the movable lamp unit (1) emits light. , each flash light source (2
)04 reaches the platen (3) surface either directly or after being reflected by the reflector H (31) as shown in FIG. 3. At this time, the main optical axis (n) of the reflector NO→
Due to the relationship, a large amount of light is distributed near each corner of the platen (3), and the light amount distribution on the platen (3) surface is as shown in Figure 8 t.
As shown in a+, the optical axis (phantom) of the imaging lens (4) is set as the axis of symmetry, and the entire surface of the copy document (2) is illuminated with this light intensity distribution.This state If the above-mentioned light intensity distribution is set to a desired value, when the original image light of the copy document (2) passes through the above-mentioned imaging lens (4), the cosine of the imaging lens (4) Even if the original image light intensity decreases based on the fourth power law characteristic, the imaging lens (4)
It becomes possible to set the amount of light of the original image immediately after passing through to be approximately equal. Therefore, without using a filter or the like to correct the characteristics of the imaging lens (41), the photosensitive surface +511
It is now possible to set the light ht distribution of the projected image on the 'ILO diagram, the same applies hereinafter) to approximately equal as shown in Figure 8 (dl), and the copy image quality based on the projected image is always maintained at a good level. It will be done.

Furthermore, when the copy magnification is set to the enlargement magnification during exposure, each movable lamp unit (1) moves as the imaging lens (4) moves, as shown in FIG. The lamp unit (to) is arranged symmetrically with the fixed lamp unit (2) with respect to the optical axis (tl) of the imaging lens (4) during magnification. In this state, when the flash light source (to) of each lamp unit (g) emits light, from the relationship of the main optical axis (nl) of the reflector IN (to), each flash light source (2) 3) A large amount of light is distributed to the area, and the light amount distribution on the platen (3) surface is distributed around the optical axis (11) of the imaging lens (4) as the axis of symmetry, as shown in Figure 8 (bl). With this illuminance distribution, for example, the entire surface of the copy document (2) of (A4) size is illuminated.At this time, the area around the platen (3) on the diagonal point (5) of the positioning reference point (RO) is illuminated. Although the light is not distributed to the area, since the copy original (2) is not usually placed in this area during enlargement, no particular inconvenience occurs during the exposure process.The copy original (2) illuminated in this way
When passing through the imaging lens (41), the original image light amount will decrease due to the characteristics of the imaging lens (4), but this decrease in light amount is relative to the optical axis aθ of the imaging lens (4). Therefore, if the light intensity distribution on the platen (3) is set to a desired value, the imaging lens (4)
It becomes possible to set the light intensity of the original image immediately after passing to be approximately equal, and accordingly, the light intensity distribution of the projected image on the photosensitive surface (5) can be adjusted to the desired state as shown in Fig. 8 (dl). Also, during enlargement, the amount of light irradiated from each flash light source (2) (to) of the fixed lamp unit ■ and movable lamp unit ■ will be approximately equal due to their arrangement. This eliminates the need to significantly increase the amount of light irradiated by a light source at a specific position, as was the case in the past, and it is possible to reduce the power consumption of the light source to the minimum necessary. Accordingly, the situation where the power source cost of the light source increases unnecessarily can be effectively avoided.

Furthermore, when the copy magnification is set to the reduction magnification during exposure, the imaging lens (4) moves from the normal magnification position to the reduction position, as shown in FIG. is the housing bottom (1b
) is set at each corner of the In this state, each movable lamp unit (7) and fixed lamp unit (2) are arranged asymmetrically with respect to the optical axis (UZ) of the imaging lens (4), but the flash of each movable lamp unit (7) If the amount of light emitted from light source 03 is appropriately reduced compared to that of fixed lamp unit ■, platen (3)
As shown in FIG. 8, the above light amount distribution is set in a state where the periphery is excessive with the optical axis (Dan 2) of the imaging lens (4) as the axis of symmetry. Therefore, the characteristics of the imaging lens (4) are effectively corrected and the photosensitive surface (5) is
The light intensity distribution of the above projection image is as shown in Figure 8 (dl).
It is set approximately evenly.

The specific configurations of the fixed lamp unit (2) and the movable lamp unit (n) are not limited to those shown in the above embodiments, and may be modified as appropriate. In addition, in the above embodiment, a fixed lamp unit ■ and a movable lamp unit (to) are provided corresponding to each corner of the platen (3).
However, the present invention is not limited to this. For example, in the conventional type shown in FIG. 9, a fixed lamp unit and a movable lamp unit are installed corresponding to each side edge of the platen (3). You may also set it up.

In this case, in order to prevent the movable lamp units from interfering with each other during movement, it is necessary to take measures such as installing adjacent movable lamp units with a difference in level, for example. Further, the support structure and the actuating means @1 of the movable lamp unit (1) are not limited to those shown in the above embodiments, and may be modified in design as appropriate. Furthermore,
Of course, the design of the drive system for the imaging lens (4) and other constituent members of the exposure apparatus can be changed as appropriate.

〔Effect of the invention〕

As described above, according to the exposure device of the copying machine according to the present invention, the light intensity distribution on the platen surface is adjusted to be too large at the periphery with respect to the optical axis of the imaging lens, assuming a corner registration ← type summer magnification type copying machine. Since we decided to distribute symmetrically in the state of
Not only can the cosine-fourth power side characteristics of the imaging lens be effectively corrected in advance by the light intensity distribution on the platen surface without being affected by the magnification change operation, but also the light intensity distribution on the platen surface can be adjusted to a desired value especially during magnification. When setting the light source to Power supply costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective explanatory view showing one embodiment of an exposure device for a copying machine according to the present invention, FIG. 2 is a sectional view taken along the line X--X in FIG. 9, and FIG. 8 is a sectional view taken along the line 1-1 in FIG. 4 and 5 are cross-sectional views taken along lines X-X and v-■ in FIG. 9, FIG. 6 is an exploded perspective view showing details around the imaging lens, and FIGS.
l is an explanatory plan view showing the operating state of the exposure device at the same magnification, enlargement, and reduction, respectively; FIGS. FIG. 8 fdl is an explanatory diagram showing the distribution of the amount of light P on each part Y of the photosensitive surface. FIG. 9 is a perspective explanatory diagram showing an example of the exposure device of a conventional copying machine.
Figure 0 is a sectional view of the main part corresponding to the line X-X in Figure 9, il1
Figure (at and (bl are X-X line and Y-Y@
FIG. 2 is an explanatory diagram showing a distribution of the amount of light P corresponding to . [Code explanation]

Claims (1)

[Claims] A housing having a closed cross-sectional structure, a platen that is attached to a rectangular opening formed at the top of the housing and constitutes a placement surface for a copy original and is formed of a transparent member, and a platen that is disposed inside the housing. a flash illumination means for instantaneously illuminating the entire surface of the copy document on the platen, and an imaging lens movably mounted along the longitudinal direction of an operating groove formed approximately in the center of the bottom of the housing; Exposure of a copying machine that projects the original image of a copy document placed on the platen onto a predetermined photosensitive surface at an arbitrary magnification by moving the image lens appropriately, using one corner of the platen as a positioning reference point. In the apparatus, the flash illumination means includes a fixed lamp unit fixedly installed corresponding to a corner or side edge of the platen located near the positioning reference point, and a fixed lamp unit fixedly installed corresponding to a corner or side edge of the platen located near the positioning reference point. It consists of a movable lamp unit that is installed and moves forward and backward toward the positioning reference point, and each lamp unit is
Each of the movable lamp units includes a flash light source and a reflector that distributes a large amount of irradiation light from each flash light source to a platen area located near each flash light source, while the movable lamp unit is configured to move the imaging lens at the time of magnification. An exposure device for a copying machine, wherein the exposure device moves along with the fixed lamp unit and is arranged symmetrically with the fixed lamp unit with respect to the optical axis of the imaging lens.