JPS6221115Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pickup that can easily read stylus pressure correction corresponding to temperature changes.

The pick-up consists of a mechanical vibration system that accurately detects the vibration waveform of the sound groove on the needle tip as mechanical vibration, and an electrical conversion system that converts this vibration into an electrical signal.
Mechanical vibration systems are generally supported by a support such as viscoelastic rubber. The pick-up's stability is one of its important features. This is because when the regenerated needle skips, larger distortions such as trace distortions occur.

The conditions that cause needle skipping will be explained below.

Consider the situation in which the playback needle is placed in the tone groove of a 45-45 record.

The stylus force W is applied as a component force of W/√2 to the two sound groove walls inclined at 45 degrees. Now, assuming that only one sound groove wall is modulated, in order to make the vibration system of mechanical impedance Zm vibrate at a speed V, |Zm|X|V|(dyne) However, |Zm|: pickup Absolute value of mechanical impedance seen from the needle tip (dyne・sec/cm) |V|: Peak amplitude in the 45-degree direction of the sound groove (cm/
sec) is required. In other words, it shows that this amount of reaction is applied to the sound groove.

Here, it is shown that when W/√2≦|Zm|X|V|, the force applied to the sound groove becomes negative.

It is well known that this is the condition for needle skipping.

By the way, the mechanical impedance seen from the tip of the pickup needle exhibits the characteristics shown in Figure 1, with the mid-low range being the stiffness control region, and this stiffness is given by the equivalent compliance seen from the tip due to the support elasticity of the vibration system.

Generally, viscoelastic rubber such as butyl rubber is used as supporting elasticity for vibration systems, but this rubber has temperature characteristics, and as the temperature increases, its elasticity and resistance decrease, so the above equivalent compliance becomes smaller, and the mechanical impedance also becomes smaller. Conversely, as the temperature decreases, the elasticity and resistance increase, so the equivalent compliance increases and the mechanical impedance also increases.

That is, as the temperature increases, the mechanical impedance decreases, and therefore the stylus pressure W, which is a condition for needle skipping, decreases. Conversely, when the temperature decreases, the mechanical impedance increases, and therefore the stylus pressure W, which is a condition for needle skipping, increases.

In other words, to prevent needle skipping,
As the temperature rises, the stylus pressure W may be reduced, and as the temperature falls, the stylus pressure W may be increased.

FIG. 1 shows the temperature characteristics (an example) of mechanical impedance at a stylus pressure of 1 g when butyl rubber is used as the support elasticity of the vibration system.

Specifically, at a temperature of 20℃ and a frequency of 100Hz,
The absolute value of mechanical impedance |Zm|
A 240dyne・sec/cm pick-up can trace up to a peak amplitude of 2.88cm/sec in the 45-degree direction of the sound groove with a stylus pressure of 1g.

When the temperature decreases by 10℃, the absolute value of mechanical impedance |Zm| becomes 288dyne・sec/cm, which is the same as 1g.
With a stylus force of , the peak amplitude in the 45 degree direction of the sound groove is 2.40
It can only be traced up to cm/sec.

Here, in order to trace the peak amplitude in the 45-degree direction of the sound groove to 2.88 cm/sec at a temperature of 10°C, the same as at 20°C, the stylus pressure must be changed to |Zm(10°C)|/|Zm(20°C) ) | must be multiplied. In the above example, the stylus force is 1g.
must be multiplied by 288/240=1.2 to get 1.2g.

As described above, unless the stylus pressure W is corrected in response to temperature changes, needle skipping may occur depending on the conditions, and the pick-up function cannot be fully demonstrated.

The present invention is an improvement over the conventional drawbacks, and as explained in the figure below, the present invention includes reversible temperature-sensitive elements 2a, 2b, 2, which change color when sensitive to different temperatures, at appropriate locations on the pick-up 1.
A temperature-sensitive material 2 formed by arranging c is integrally provided, and each reversible temperature-sensing element 2a, 2b, 2 of this temperature-sensitive material 2
It has a structure in which a stylus pressure correction display 3 corresponding to the temperature is applied to the part c.

The stylus pressure correction display shows the corrected stylus pressure corresponding to the temperature, for example -0.2g, -0.1g, +0.1g, as shown in Figure 2.
..., UP, DOWN, etc. are displayed.

According to the above structure, by applying the appropriate stylus pressure at room temperature and then correcting the stylus pressure according to the display on the temperature-sensitive material 2, the optimum stylus pressure can always be obtained. This has the advantage that it is possible to obtain a reproduced sound with high quality, and the commercial value is also significantly increased.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the temperature characteristics (one example) of mechanical impedance, and FIG. 2 is a diagram showing the structure of the present invention. 1 is a pickup; 2a, 2b, and 2c are temperature-sensitive elements; 2 is a temperature-sensitive material; and 3 is a stylus pressure correction display.

Claims (1)

[Scope of utility model registration request] A temperature-sensitive material 2 formed by arranging reversible temperature-sensitive elements 2a, 2b, and 2c that change color when sensitive to different temperatures is integrally provided at appropriate locations, and each reversible temperature-sensitive element 2a, 2c of the temperature-sensitive material 2 is provided. A pick-up characterized in that a stylus pressure correction display 3 corresponding to temperature is provided on portions 2b and 2c.