JPH0562726B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an exposure device for a copying machine, and in particular,
The present invention relates to an exposure device of a type used in a variable magnification type 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-section structure, as shown in FIGS. 9 and 10, for example. An opening is opened and a platen 3 made of glass or the like on which the original copy 2 is placed is mounted in the opening, and a lens mounting hole is opened approximately in the center of the bottom 1b of the housing 1. An imaging lens 4 is attached to the housing 1, and a flash illumination means S is disposed inside the housing 1. This type of exposure apparatus instantly illuminates the entire surface of the copy document 2 on the platen 3 with the flash illumination means S during exposure, and images the original image of the copy document 2 through the imaging lens 4 at a predetermined position. The image is projected onto a photosensitive surface 5.

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 copy image, which may impair the quality of the copy image. , it is necessary to keep the light intensity distribution of the projected image on the photosensitive surface 5 uniform. In this case, the imaging lens 4 has a cosine fourth law characteristic,
In other words, since the amount of original image light passing through the imaging lens 4 is reduced by cos ⁴ θ depending on the angle of view θ with respect to the imaging lens 4, the characteristics of the imaging lens 4 must be taken into account. Must.

Therefore, in conventional exposure apparatuses, a flash illumination means S is usually used that takes into account the characteristics of the imaging lens 4, as shown by the solid line in FIG. 11a.
The light intensity distribution on the platen 3 surface is given as a peripheral excess state, and the characteristics of the imaging lens 4 are corrected in advance, and the light intensity distribution of the projected image on the photosensitive surface 5 is changed as shown in FIG. 11b. I try to keep it uniform. As this type of flash illumination means S, for example, as shown in FIG.
Four lamp units 6 are fixedly installed on the bottom 1b of the housing 1 in correspondence with each side edge of the platen 3, and each lamp unit 6 is connected to a flash light source 7.
(Specifically, 7a to 7d, and a reflector 8 (specifically, 8a to 7d) that distributes a large amount of the irradiation light from each flash light source 7 to the vicinity of each side edge of the corresponding platen 3.
8d) to 8d), whereby the platen 3
A device in which the amount of peripheral light is set to be greater than the amount of light at the center of the platen 3 has already been provided.

[Problems to be solved by this invention]

Although such a conventional exposure device is based on a constant magnification type copying machine, this type of exposure device has a corner registration system in which one corner of the platen 3 is the positioning reference point R ₀ of the copy document 2. type (hereinafter referred to as corner register type) variable magnification type copying machine, an operating groove (not shown) extending in a diagonal direction including the positioning reference point R ₀ of the platen 3 is formed approximately at the center of the bottom 1b of the housing 1. The original image of the copy document 2 is enlarged or reduced by moving the imaging lens 4 in the vertical direction and along the longitudinal direction of the operating groove as shown by the one-dot chain line and the two-dot chain line in FIG. The image must be 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.
As shown in Figure a, even if the light intensity distribution on the three platen surfaces is set as desired symmetrical with respect to the optical axis l of the imaging lens 4 at the same magnification, the light intensity distribution on the three platen surfaces at the time of zooming is The light amount distribution becomes asymmetrical with respect to the optical axes l ₁ and l ₂ of the imaging lens 4. For this reason, when changing the magnification, the correction of the characteristics of the imaging lens 4 tends to be insufficient, and the light intensity distribution of the projected image on the photosensitive surface 5 becomes uneven, impairing the copy image quality. occurs.

As a means to solve 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, as shown by the dashed line or the dashed double dot line in Fig. 11a. _The platen ₃ is also
It is conceivable to maintain the light intensity distribution on the surface as symmetrical, but in this type, especially during magnification, the imaging lens 4 moves from the same magnification position to the positioning reference point R ₀ side. When the 9th
As shown by the dashed line in the figure and FIG. 11a, it is necessary to significantly increase the amount of light in the area of the platen 3 located near the diagonal point R of the positioning reference point _R0 . In this case, each flash light source 7b, 7c of the lamp unit 6 installed on the diagonal point R side
It becomes necessary to significantly increase the amount of light emitted from the flash light sources 7b and 7c.
A problem arises in that the power consumption of the flash light sources 7b and 7c increases unnecessarily, and the cost of the power supply for the flash light sources 7b and 7c increases.

[Means and actions for solving problems]

This invention was made in view of the above-mentioned problems, and the problem is that the power consumption of the light source itself increases dramatically, assuming a corner register type variable magnification copying machine. While effectively preventing this, the light intensity distribution on the platen surface can be maintained in a desired state without being affected by the magnification change operation, and the imaging lens characteristics can be effectively corrected in advance 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. In order to achieve this object, the present invention improves the flash lighting means disposed within the housing.
A fixed lamp unit is fixedly installed corresponding to a corner or side edge of the platen located near the positioning reference point of a copy document, and a movable lamp unit is movable corresponding to another corner or side edge of the platen. each lamp unit is configured with 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;
The movable lamp unit is moved along with the movement of the imaging lens during magnification, and the movable lamp unit and the fixed lamp unit are arranged symmetrically with respect to the optical axis of the imaging lens during magnification. .

〔Example〕

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

The exposure apparatus according to the embodiment shown in FIGS. 1 to 6 is used in a corner register type variable magnification copying machine, and its basic structure includes a housing 1 having a substantially rectangular closed cross-sectional structure; a platen 3 attached to a rectangular opening formed at the top 1a of the housing 1; a flash illumination means S disposed inside the housing 1 to instantaneously illuminate the entire surface of the copy document 2 on the platen 3; An imaging lens 4 is mounted so as to be movable along the longitudinal direction of an operating groove 10 formed approximately at the center of the bottom 1b of the housing 1.
It is equipped with

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 one corner of the platen 3 is used for positioning the copy document 2. It is given as the reference point R ₀ . The operating groove 10 extends symmetrically along a diagonal line including the positioning reference point _R0 of the platen 3, with the center of the housing bottom portion 1b as a boundary.

The flash illumination means S includes a fixed lamp unit 20 installed at the bottom 1b of the housing 1 corresponding to one corner of the platen 3 on the side of the positioning reference point _R0 , and a fixed lamp unit 20 installed at the bottom 1b of the housing 1 corresponding to the other corner of the platen 3. Movable lamp units 30 (specifically, 30a to 3
0c), and the fixed lamp unit 20
The lamp holder 21 is attached to the bottom 1b of the housing 1.
A holding bracket 23 holds a flash light source 22 bent at a substantially right angle to the lamp holder 21.
while holding the flash light source 2 through the
A reflector 24 is disposed on the non-platen 3 side of the lamp 2, and this reflector 24 is fixed to the lamp holder 21 via a support bracket 25. On the other hand, the movable lamp unit 30 has a pair of guide rails 31 integrally formed on the bottom 1b of the housing 1, each extending from a corresponding corner toward the fixed lamp unit 20, and a lamp holder mounted on each guide rail 31. 32 is slidably attached to the lamp holder 32, and a flash light source 33 bent at a substantially right angle is held on the lamp holder 32 via a holding bracket 34, and a reflector 35 is arranged on the non-platen 3 side of each flash light source 33. Each reflector 35 is fixed to the lamp holder 32 via a support bracket 36. The reflectors 24 and 35 of each of the lamp units 20 and 30 have a main optical axis n that is directed toward the platen 3 area located near each flash light source 22 and 33, as shown in FIG. A large amount of the irradiated light from the light sources 22 and 33 is distributed to the predetermined area of the platen 3.

Further, the driving means 40 for driving each of the movable lamp units 30 includes, for example, as shown in FIG. ), a guide pulley 42 for wrapping each drive wire 41 in an appropriate position, and a drive motor 43.
Three drive pulleys 44 (specifically, 44a to 44c) of different diameters are connected and fixed to the shaft of the drive motor 43 and to which the other ends of the drive wires 41 are respectively connected, and each movable lamp unit. 30 toward the fixed lamp unit 20. In this embodiment, the drive motor 43 is controlled by a microprocessor that outputs a control signal based on information from the copy magnification selection section, and the drive wires 41 are Each movable lamp unit 30 is set at a corner of the housing bottom 1b by appropriately winding it up against the urging force of the spring 45. At the same time, when enlarging, each drive wire 41 is appropriately wound back and the urging force of each spring 45 is applied. , each movable lamp unit 30 is appropriately moved toward the fixed lamp unit 20 side, and the optical axis l ₁ of the imaging lens 4 during magnification is adjusted (see FIG. 7b).
In contrast, each movable lamp unit 30 is arranged symmetrically with the fixed lamp unit 20.

Furthermore, as particularly shown in FIG. 6, the imaging lens 4 is supported via a lifting device 60 on a movable plate 50 that moves forward and backward along the operating groove 10. In this embodiment, the movable plate 50 is slidably mounted along a pair of support rails 51 supported and fixed to the housing bottom 1b, and approximately in the center of the movable plate 50 is a circular transmission hole (see FIG. (not shown) is opened, and a guide tube 52 is erected around this transmission port, and the imaging lens 4 is fitted into the upper end opening of the guide tube 52 so as to be movable up and down together with the case 4a. . Also,
The elevating device 60 has a pair of guide columns 61 erected on the movable plate 50, a pair of guide pieces 62 protruding from the case 4a of the imaging lens 4, and the guide columns 61 have a pair of guide columns 61 erected thereon. By slidably attaching the piece 62, the imaging lens 4 can be supported up and down. In FIG. 6, 58 is a drive wire for moving the movable plate 50 forward and backward, 54 is a holding spring that maintains the position of the movable plate 50 by following the amount of movement of the drive wire 58, and 68 is a drive wire for moving the movable plate 50 forward and backward. A drive wire 64 is the drive wire 63 for raising and lowering.
This is a guide roller that spans the material to an appropriate position. As shown in FIG. 7a, the imaging lens 4 is set at the neutral position of the operating groove 10 at the same magnification, and projects the original image of the copy document 2 onto the photosensitive surface 5 at the same magnification. During the expansion, the 7th
As shown in Figure b, the position is set at one end of the operating groove 10 near the positioning reference point R ₀ at a position higher than the position at the _same magnification _. While it is enlarged and projected onto the photosensitive surface 5, when it is reduced, as shown in _FIG . The original image of the copy document 2 is reduced to _A4 size and projected onto the photosensitive surface 5.

Therefore, according to the exposure device of the copying machine according to this embodiment, when the copy magnification is set to equal magnification during exposure, the movable lamp unit 30 is moved to each corner of the housing bottom 1b as shown in FIG. 7a. 3, each flash light source 22, 23 of the fixed lamp unit 20 and movable lamp unit 30 emits light, and the light from each flash light source 22, 23 is transmitted directly or through a reflector 24, as shown in FIG. After being reflected by 35, it reaches the 3rd surface of the platen. At this time, the main optical axis n of the reflectors 24 and 35
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 3rd surface of the platen is
As shown in FIG. 1A, the optical axis l of the imaging lens 4 is set as the axis of symmetry, and the entire surface of the copy original 2 is illuminated with this light amount distribution. In this state, if the light amount distribution is set to a desired value, when the original image light of the copy document 2 passes through the imaging lens 4, it will be Even if the amount of original image light decreases, it is possible to set the amount of original image light immediately after passing through the imaging lens 4 to be substantially uniform. For this reason,
Without using a filter or the like to correct the characteristics of the imaging lens 4, the light intensity distribution of the projected image on the photosensitive surface 5 (see FIG. 10, the same applies hereinafter) is set to be approximately uniform as shown in FIG. 8d. This makes it possible to maintain good copy image quality based on the projected image at all times.

Furthermore, when the copy magnification is set to the enlargement magnification during exposure, each movable lamp unit 30 moves as the imaging lens 4 moves, as shown in FIG. The fixed lamp unit 20 and the fixed lamp unit 20 are arranged symmetrically with respect to the optical axis l ₁ of the imaging lens 4 at the time. In this state, when the flash light sources 22, 33 of each lamp unit 20, 30 emit light, the reflector 24,
35, each flash light source 2
A large amount of light is distributed to the areas of platen 3 near 2 and 33, and as shown in _FIG . With this illuminance distribution, the entire surface of the copy document 2 of, for example, _A4 size is illuminated.
At this time, light is not distributed around the platen 3 on the diagonal point R side of the positioning reference point R ₀ , but since the copy original 2 is not normally placed in this area during enlargement, this is particularly inconvenient during the exposure process. does not occur. The light intensity of the original image of the copied original 2 illuminated in this way decreases due to the characteristics of the imaging lens 4 when it passes through the imaging lens 4, but this decrease in light intensity is caused by the optical axis l of the imaging lens 4. Since the amount of light increases symmetrically with respect to ₄ , if the light amount distribution on the three platen surfaces is set to a desired value, it is possible to set the original image light amount immediately after passing through the imaging lens 4 to be approximately uniform. Accordingly, the light amount distribution of the projected image on the photosensitive surface 5 is maintained in a desired state as shown in FIG. 8d. Furthermore, when enlarging, the amount of light irradiated from each flash light source 23, 33 of the fixed lamp unit 20 and movable lamp unit 30 need only be approximately equal in view of their arrangement. It is no longer necessary to significantly increase the amount of light irradiated by a light source at a specific position, and it is therefore necessary to reduce the power consumption of the light source to the necessary minimum, thereby eliminating unnecessary power supply costs for the light source. The situation of bulkiness is effectively avoided.

Furthermore, when the copy magnification is set to the reduction magnification during exposure, the imaging lens 4 moves from the same magnification position to the reduction position, as shown in FIG. 7c.
Each movable lamp unit 30 is set at each corner of the housing bottom 1b, which is the same as the position when the magnification is the same. In this state, each movable lamp unit 30 and fixed lamp unit 20 are arranged asymmetrically with respect to the optical axis _l2 of the imaging lens 4, so that the amount of light irradiated from the flash light source 33 of each movable lamp unit 30 is reduced. If the amount of light is appropriately reduced compared to that of the fixed lamp unit 20, the light intensity distribution on the platen 3 will be in a state where there is too much light at the periphery with the optical axis _l2 of the imaging lens 4 as the axis of symmetry, as shown in FIG. 8c. is set to For this reason, the characteristics of the imaging lens 4 are effectively corrected as in the case of normal magnification and enlargement, and the light intensity distribution of the projected image on the photosensitive surface 5 is as shown in FIG. 8d.
It is set approximately uniformly.

The specific configurations of the fixed lamp unit 20 and the movable lamp unit 30 are not limited to those shown in the above embodiments, and may be modified as appropriate. Furthermore, in the above embodiment,
Although a fixed lamp unit 20 and a movable lamp unit 30 are installed corresponding to each corner of the platen 3, the present invention is not necessarily limited to this.
For example, in the conventional type shown in FIG. 9, a fixed lamp unit and a movable lamp unit may be installed corresponding to each side edge of the platen 3, respectively. 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. Further, the support structure of the movable lamp unit 30 and the driving means 40 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 of the imaging lens 4 and other constituent members of the exposure apparatus can be changed as appropriate.

〔Effect of the invention〕

As explained above, according to the exposure device for a copying machine according to the present invention, the light intensity distribution on the platen surface is adjusted to the peripheral area with respect to the optical axis of the imaging lens, assuming a corner registration type variable magnification copying machine. Since the distribution is symmetrical in each state, the cosine fourth law characteristic of the imaging lens can be effectively corrected in advance by the light intensity distribution on the platen surface without being affected by the magnification change operation. Sometimes, when setting the light intensity distribution on the platen surface to a desired value, it is no longer necessary to extremely increase the amount of light irradiated to the platen surface, as in the past, so the power consumption of the light source itself increases unnecessarily. This situation can be effectively avoided, and the power source cost for the light source can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective explanatory view showing an embodiment of an exposure device for a copying machine according to the present invention, and FIG.
Line sectional view, Figure 3 is a line sectional view in Figure 2,
Figures 4 and 5 are the - line and - line in Figure 3.
6 is an exploded perspective view showing details around the imaging lens; FIGS. 7a to 7c are plan explanatory views showing operating states of the exposure device at the same magnification, enlargement, and reduction, respectively; Figures 8a to 8c show the amount of light P at each part
FIG. 8d 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 a conventional exposure device of a copying machine, and FIG. 9, and FIGS. 11a and 11b are explanatory diagrams showing the distribution of the amount of light P, corresponding to the X-X line and the Y-Y line in FIG. 10. Symbol explanation: S...flash illumination means, l,
l ₁ ． l ₂ ...Optical axis of the imaging lens, 1...Housing,
2... Copy original, 3... Platen, 4... Imaging lens, 5... Photosensitive surface, 10... Operating groove, 20...
Fixed lamp unit, 22...flash light source,
24...Reflector, 30...Movable lamp unit, 33...Flash light source, 35...Reflector.

Claims (1)

[Claims] 1. A housing with a closed cross-section structure, a platen that is attached to a rectangular opening provided at the top of the housing and forms a placement surface for a copy original and is made of a transparent member, and is disposed inside the housing. and an imaging lens that is movably mounted along the longitudinal direction of an operating groove formed approximately in the center of the bottom of the housing. A copying machine that projects an original image of a copy document placed on a platen onto a predetermined photosensitive surface at an arbitrary magnification by moving an imaging lens appropriately, using one corner of the platen as a positioning reference point. In the exposure 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 at the position and moves forward and backward toward the positioning reference point side, and each lamp unit has a flash light source and a platen area located near each flash light source that emits the irradiated light from each flash light source. The movable lamp unit moves with the movement of the imaging lens during magnification, and is arranged symmetrically with the fixed lamp unit with respect to the optical axis of the imaging lens. Features: Copying machine exposure device.