JPH11190819A5 - - Google Patents

Description

[Claims]
[Claim 1 ] An optical system having a lens system composed of a plurality of lenses and one image pickup element or display element, characterized in that the lenses are tightly attached to each other, or are bonded together or filled with resin so that there is no air gap between the lenses and between the lens and the image pickup element or display element.

In the optical system of the first composition of the present invention described above, in order to effectively correct astigmatism throughout the entire system, it is desirable that the central thickness of the radial type gradient index lens element having positive refractive power be approximately 1/4 pitch, and it is desirable that the following condition (3) be satisfied:
(3) 0.15<d(p)/p<0.40
Here, d(p) is the central thickness of the radial type gradient index lens element having positive refractive power, and p is the pitch of the radial type gradient index lens element material, which is given by the following formula (e).
p=2π{N ₀ /-2N ₁ } ^1/2 (e)

In this lens system, it is desirable that the amount of deviation δ of the image-forming plane from the image-side surface of the lens in the optical axis direction satisfies the following condition (6):
(6) -0.5mm<δ<2.0mm

Figure 17 shows a lens system of the fourth configuration of the present invention, which is an imaging module that integrates the lens system of Example 8 shown in Figure 13 with an imaging element. In Figure 17, 31 is the lens system, 32 is the imaging chip of the imaging element, 33 is the imaging surface of the imaging element, and 34 is the ceramic substrate of the imaging element, and the flat portion that is the final surface of lens system 31 (lens HL10 of Example 8) is directly bonded to the imaging chip of the imaging element. An epoxy-based adhesive or the like is used to bond this imaging chip 32 and lens HL10.

In order to overcome the above drawbacks, the present invention employs a configuration as shown in Fig. 20. In the figure, 41 denotes a lens, 42 denotes an imaging element substrate (IC chip), 43 denotes an effective photoelectric conversion surface, 44 denotes an ineffective photoelectric conversion pixel and circuit group, 45 denotes a flexible electrical substrate, 46 denotes a bonding electrode, and 47 denotes a wire connection.

20B, bonding electrode 46 is positioned away from the contact surface between lens 41 and imaging element substrate 42, so that even when lens 41 is in close contact, there is no interference between lens 41 and connection portion 47. To achieve this configuration, it is desirable to use a two-dimensional imaging element that sufficiently covers effective photoelectric conversion surface 43 of imaging element substrate 42 and has a flat surface on which adhesion is possible, except for the bonding area on imaging element substrate 42.

The signals _I1 and _I2 output from the light position detecting element 14 are sent to a decision circuit 15 shown in FIG. 28 , which calculates the distance to the subject O from the signal currents _I1 and _I2 using the above equation (k) to obtain a distance measurement signal I.

When the taking lens 21 is in focus on the subject O, the subject image is in the state of 30A, as indicated by the group of arrows 30. In this state, if the taking lens 21 is extended forward relative to the subject O (moved in a direction toward the subject O), the image on the light-receiving surface will be in the state of 30B. Conversely, if the taking lens 21 is retracted (moved in a direction away from the subject O), the image on the light-receiving surface will be in the state of 30C. Therefore, if image sensors 25, 26 having a plurality of microphotoelectric conversion elements arranged as _Y1 to _Y6 and _Z1 to _Z6 shown in Figure 30 are used as the photoelectric conversion means 25, 26, the scanning circuit 9 synchronously scans each of the photoelectric elements of these image sensors ₂₅ , 26 _in the directions Y1 to _Y6 and Z1 to _Z6 at the same time, and each photoelectric element outputs a phase signal corresponding to the brightness of the image received. When the lens is out of focus, the phase comparison circuit 27 detects whether the phase is advanced or delayed between the two phase signals, and this makes it possible to detect, for example, by a meter 28, whether the lens is in focus or out of focus .