JPH04290090A - How to assemble a 3-panel camera imaging block - Google Patents

Abstract

PURPOSE:To attain high accuracy and stabilization for the image-forming plane positioning of a solid-state image pcikup element by adhering closely and fixing without separating between color separation prism members and between the prism member and the solid-state image pickup element and to efficiently perform assembling work in the assembling of the color separation image pickup block of a three-plate type color video camera using three solid-state image pickup elements. CONSTITUTION:Three prism members 21, 22, and 23 and three solid-state image pickup elements 30, 31, and 32 are adhered closely at a prescribed joining plane by using ultraviolet hardening type adhesive with thermosetting property. After optical path length adjustment and position alignment are performed by finely moving each member and element as observing the image pickup signals of the elements 30, 31, and 32, utraviolet rays are projected, and furthermore, they are heated, and each member and element can be fixed by sufficiently hardening the adhesive.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to television cameras, video cameras, etc. equipped with solid-state image sensors.
The present invention relates to a method for assembling a plate camera imaging block.

0002

2. Description of the Related Art In recent years, a three-chip color camera (hereinafter referred to as a three-panel camera) using three solid-state image sensors has been developed and is becoming widely used.

FIG. 3 is a sectional view of an imaging block of a conventional three-panel camera. In the figure, 1 is a light beam that has passed through an imaging lens, and 2 is a three-color separation prism consisting of prism members 2a, 2b, and 2c. The light beam 1 is separated into three primary color light beams 5, 6, and 7 by the dichroic mirrors 3 and 4 provided in the three-color separation prism 2, and the solid-state image sensors 8 and 9 respectively
, 10. The prism members 2b and 2c are joined in close contact, and the prism members 2a and 2b are joined with an interval of several tens of μm between them.

[0004] The light beams 5 and 6 that have been separated and reflected into the three primary colors by the dichroic mirrors 3 and 4 are reflected again by total internal reflection, and are emitted as a light beam that forms a front image rather than an inverted image (mirror image). Since the light flux is incident on the solid-state image sensor, the image signals of the solid-state image sensors 8, 9, and 10 are combined to obtain a color television signal.

[0005] In such a conventional three-panel camera, it is necessary to superimpose three-color subject images with high precision. If the overlay accuracy, that is, the registration accuracy is poor, color shifts and moiré false signals will occur, resulting in a slight deterioration of image quality. Positioning of the solid-state image pickup device requires accuracy of several tens of μm in the optical axis direction due to the depth of focus, and on the order of μm in the direction within the image plane of the object. Similarly, the positional stability of the solid-state image sensor against thermal expansion and vibration shock requires the same degree of precision, and this is called registration stability.

[0006] In particular, with the recent trend toward increasing the number of pixels in solid-state image sensing devices, the pixel pitch has been decreasing, and therefore higher registration accuracy and stability than ever before are required.

Now, regarding the attachment of the solid-state imaging devices 8, 9, and 10 to the three-color separation prism 2, conventionally, the light beams 5,
6 and 7, and the pixels of the solid-state image sensors 8, 9, and 10 are adjusted in a predetermined positional relationship. ) was attached and fixed to each light beam emitting surface by gluing it to the surrounding area.

The reason why the exit surface of the three-color separation prism 2 and the solid-state image sensor 8 are separated is that there is a large dispersion in the position of the prism exit surface. This is to ensure a large range and avoid inability to adjust due to collision between the two during adjustment. The prism members 2a, 2b, and 2c have processing errors in their dimensions, and especially require a polishing process, so there is a problem in that it is more difficult to maintain length accuracy than angular accuracy.

Furthermore, since an air gap is formed, the assembly process becomes somewhat complicated, and it becomes difficult to ensure the positional accuracy of the exit surface. Therefore, the solid-state image sensors 8, 9, 10
The 6-axis registration adjustment was performed by separating the 3-color separation prism 2 and the 3-color separation prism 2 from each other.

0010

[Problems to be Solved by the Invention] However, the stability of the registration against thermal expansion and vibration shock, and furthermore, the incidence surfaces of the solid-state image sensors 8, 9, and 10 and the three-color separation prism 2
Since there is a strong demand for suppression of reflected light at the exit surface of the camera, as well as dustproof properties and a shortened optical path length, it has been a big problem to make the imaging blocks separated as in the past.

The present invention solves the above-mentioned problems, and provides a three-panel camera imaging block that can efficiently make the structure of the imaging block into a close-contact structure, facilitate registration adjustment, and realize high registration stability. The purpose is to provide an assembly method.

0012

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for assembling a three-color separation prism having three prism members and a three-panel camera imaging block having three solid-state imaging devices. After the prism member and the three solid-state image sensors are brought into close contact with each other on all bonding surfaces using a liquid ultraviolet light-curing adhesive, the position information of the solid-state image sensors is detected from the image signal, and the front The rear prism member is sequentially moved along the joint surface of the prism member to adjust the optical path length, and the solid-state image sensor is moved along the exit surface of the prism member to adjust the alignment of the pixels of the solid-state image sensor. After this, each member or element is fixed by irradiating ultraviolet light to cure the ultraviolet light-curable adhesive.

[0013]

[Operation] In the present invention, as described above, assembly and adjustment are performed with all bonding surfaces in close contact with adhesive, so the prism assembly and solid-state image sensor mounting processes, which were previously separate processes, are combined into one. This allows for an efficient assembly process,
The assembly work can be carried out while monitoring the imaging signal in the same state as after assembly (after curing). Therefore, the assembly dimensions can be easily adjusted to ensure the relative accuracy of the optical path length of each color, and the solid-state image sensor Registration adjustment can also be simplified. As a result, it is possible to improve registration stability and simplify the mounting configuration.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for assembling a three-panel camera imaging block according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a sectional view of a three-chip camera imaging block of this embodiment. In the figure, 21, 22, and 23 are prism members of a three-color separation prism. 24 is a dichroic mirror surface that receives the light beam 25 from the imaging lens and reflects the light beam 26 in the blue wavelength band, and the prism member 21
Provided on the surface. A dichroic mirror surface 27 reflects a light beam 28 in the red wavelength band and transmits a light beam 29 in the green wavelength band, and is provided on the surface of the prism member 22. 30,
31 and 32 are the output surfaces 3 of the prism members 21, 22, and 23.
3, 34, and 35 are solid-state image sensors.

There is no air gap in the dichroic mirror surface 24, and the light beam 28 in the red wavelength band is reflected once and then emitted, so the subject image becomes an inverted image (mirror image). Invert. 3 like this
The form of the color separation prism is known.

[0017] First, the prism members 21, 22, 2 are assembled.
3 are brought into close contact with dichroic mirror surfaces 24 and 27 with a liquid ultraviolet light curing adhesive sandwiched therebetween. Thermosetting properties are imparted to this ultraviolet light-curable adhesive. Similarly, the solid-state image sensors 30, 31, and 32 are also tightly attached to the emission surfaces 33, 34, and 35 with a liquid ultraviolet light-curing adhesive interposed therebetween, and the whole is held in a temporarily assembled state. Each component may be held after or before being brought into close contact with each other, but each part is held by a position adjustment mechanism that presses against the front joint surface and is movable finely along the joint surface. In reality, the adhesion force is generated by the surface tension of the adhesive, so strong pressing force is not required.

FIG. 2 is a diagram showing the direction of the fine movement, that is, the degree of freedom of movement for assembly and adjustment using arrows. The prism member 22 is allowed to move slightly along the dichroic mirror surface 24 which is the joint surface with the front prism member 21 in directions 36 and 37 in which the prism member 22 can move slightly as shown by arrows. The prism member 23 is allowed to move slightly along a dichroic mirror surface 27 that is a joint surface with the front prism member 22 in directions 38 and 39 in which the prism member 23 can move slightly as indicated by arrows. The prism member 21 is held at a predetermined reference position and is not moved slightly. The solid-state image sensor 30 is arranged along the emission surface 33.
1 is along the output surface 34, and the solid-state image sensor 32 is along the output surface 3.
5, each solid-state image sensor is allowed to move finely in directions indicated by arrows X, Y, and R in the figure.

Returning to FIG. 1, after each component is held, the solid-state imaging devices 30, 31, and 32 are brought into an imaging state, and a test chart serving as a reference for registration adjustment is imaged. First, the imaging signals of the solid-state imaging devices 30 and 31 are monitored, and after focusing the imaging lens on the solid-state imaging device 30, the prism member 22 is moved to the dichroic mirror surface 24 so that the imaging state of the solid-state imaging device 31 is the best. Adjust the optical path length by making slight movements along the

Next, the imaging signal of the solid-state imaging device 32 is monitored, and the prism member 23 is slightly moved along the dichroic mirror surface 27 to adjust the optical path length so that the imaging state is optimal. Next, the pixel position of the solid-state image sensor 30 is slightly moved along the output surface 33 so that the pixel position is at a predetermined position with respect to the test chart for alignment adjustment. Solid-state image sensor 31, 32
The pixels are also slightly moved along the emission surfaces 34 and 35 so as to have a predetermined positional relationship with respect to the test chart, thereby adjusting the pixel alignment.

[0021] In this state, ultraviolet light is irradiated to harden the adhesive on each joint surface, but this may be done temporarily. After releasing from holding, place it in a heating cabinet to completely harden it. The use of ultraviolet curable adhesives with thermosetting properties increases the certainty of curing, and can also be used in cases where UV irradiation is not sufficient due to the absorption of ultraviolet rays by the glass material used in the prism member. Even when UV light irradiation is insufficient due to the holding mechanism, sufficient curing strength can be obtained by thermal curing.

As described above, in the embodiment of the present invention, it is possible to bring the three-color separation prism and the solid-state image sensor into close contact with each other with high precision. Furthermore, since the joint surfaces remain in close contact throughout, the assembly is dust-proof from the beginning to the end, and productivity is improved. It should be noted that the close-contact structure eliminates the need for anti-reflection treatment on the interface since there is no reflective interface, which is advantageous in reducing flare. Of course, the present invention does not require parts corresponding to the connecting members conventionally required for fixing the solid-state image sensors apart, thereby achieving miniaturization and simplification.

Note that the prism members 21, 22, and 23 may have a composite structure in which a color correction filter, an infrared light cut filter, an optical low-pass filter, or the like is bonded in advance to the output surface. Due to the composite structure, the dimensions of the prism members 21, 22, and 23 tend to have length errors, but in the present invention, this can be corrected by assembly adjustment, so there is no problem.

[0024]

[Effects of the Invention] As is clear from the above embodiments, according to the present invention, the prism assembly and solid-state image sensor mounting processes, which were conventionally separate processes, can be combined into one efficient manufacturing process. Therefore, the relative accuracy of the optical path length of each color can be ensured at the same time by adjusting the assembly dimensions.

Further, the position of the solid-state image pickup device in the optical axis direction is adjusted by the prism exit surface, and the registration adjustment of the solid-state image pickup device can be simplified. As a result of easy adhesion of the solid-state imaging device to the prism exit surface, the registration stability of the three-panel camera imaging block is improved,
It is possible to provide an efficient and excellent method for assembling a three-chip camera imaging block, such as simplifying the mounting configuration, improving flare characteristics and dustproof properties, and omitting the antireflection treatment process.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a three-panel camera imaging block in an embodiment of the present invention.

FIG. 2 is a perspective view showing fine adjustment operations of each member in a method for assembling a three-panel camera imaging block according to an embodiment of the present invention.

[Figure 3] Cross-sectional view of a conventional three-panel camera imaging block

[Explanation of symbols]

21 Prism member 22 Prism member 23 Prism member 30 Solid-state image sensor 31 Solid-state image sensor 32 Solid-state image sensor 36 Fine movement possible direction 37 Fine movement possible direction 38 Fine movement possible direction 39 Fine movement possible direction

Claims (2)

[Claims] Claims: 1. A method for assembling a three-color separation prism having three prism members and a three-panel camera imaging block having three solid-state imaging devices, wherein the prism members and three solid-state imaging devices are assembled in a liquid state. After all joint surfaces are brought into close contact using an ultraviolet curing adhesive, the position information of the solid-state image sensor is detected from the imaging signal, and the rear prism member is attached along the joint surface of the front prism member. is sequentially moved to adjust the optical path length, and the solid-state image sensor is moved along the exit surface of the prism member to adjust the alignment of the pixels of the solid-state image sensor, and then ultraviolet light is irradiated to adjust the optical path length. A method for assembling a three-panel camera imaging block by curing a light-curing adhesive. 2. The three-panel camera imaging block according to claim 1, wherein the ultraviolet light curing adhesive is given thermosetting properties, and after being irradiated with ultraviolet light to temporarily fix the adhesive, curing is completed by heating. How to assemble.