Any person, or agent or officer thereof, employing either directly or indirectly through third persons, or any parent or guardian of a minor affected by this article who violates any provision hereof, or who employs, or permits any minor to be employed in violation hereof, is guilty of a misdemeanor, punishable by a fine of not less than one thousand dollars ($1,000) nor more than five thousand dollars ($5,000) or imprisonment in the county jail for not more than six months, or both. Any person who willfully violates this article shall, upon conviction, be subject to a fine of not more than ten thousand dollars ($10,000) or to imprisonment in the county jail for not more than six months, or both. No person shall be imprisoned under this section, except for an offense committed after the conviction of that person for a prior offense under this article.